Opinions on empeg sound stage

Posted by: rob

Opinions on empeg sound stage - 27/06/2000 15:34

Hi

I've received some negative comments from a client - we have our own opinions about this, but in the interest of free and open discussion I'd like to hear what our clients think.

Here's the enquiry, word for word apart from quoting names:

"My brother (an IASCA certified judge) says that the unit's sound
staging is lacking. He was speaking with a friend of his, *****
(of Car Sound Magazine) about the quality of MP3s. ***** is a
true believer in MP3s and went on to say that he had contacted empeg
asking for a demo unit to review, but empeg would not allow him
access to one. A reader of his magazine happened to own an empeg and
sent him one to review. His results were that the sound staging in
the unit is poor."

I don't remember the loan request from CSM specifically, but we have refused all recent requests because we don't have any players!

So, any opinions?

Rob


Posted by: tfabris

Re: Opinions on empeg sound stage - 27/06/2000 15:58

I am not an expert in sound staging (gotta talk to Doug about that one- in fact, I have my suspicions that your anonymous client might be Doug), but I want to make it clear that there's going to be two separate levels of discussion here: The sound staging of MP3 files at various bitrates, and the sound staging of the Empeg's output channels.

Clearly, in order to make an apples-to-apples comparison, you'll need the Empeg to be able to play raw .WAV files. Now, I'm a firm believer that high-bitrate MP3 files can sound every bit as good as the original source material, but there's some well-known technological limitations to MP3 which might affect the soundstage. Lack of ultra-high-frequency data, for example. This isn't the Empeg's fault, it's the fault of the MP3 file format.

Once you get the Empeg to play raw .WAV files, and get a situation where you can do a true comparison between another stereo and the Empeg using the same amps/speakers, there's still another thing that needs to be taken into account before you can make an apples-to-apples comparison: Equalization. All equipment, whether home-stereo or car-stereo, has a different EQ response curves even when set "flat". Car stereos especially I've noticed to be pretty bad in that they boost the highs and lows unnaturally even in "flat" mode. The Empeg's output, IMHO, is flatter at the default settings than other consumer car stereos I've heard. So you'll have to take that into account before making soundstage comparisions.

Finally, once you've solved the above problems, any direct equipment competitions should always be done double-blind to get accurate results.

___________
Tony Fabris
Posted by: dionysus

Re: Opinions on empeg sound stage - 27/06/2000 16:02

Honestly, I always felt that the base/trebble on my apline head unit sounded much better (crisper/brighter) then the empeg. I've attributed this to the mp3 compression though and bad equilization on my part though, and have not blamed the empeg.. (well - except for the noise floor on the mark1's, but you've fixed that:) )
-mark

...proud to have owned one of the first Mark I units
Posted by: TommyE

Re: Opinions on empeg sound stage - 27/06/2000 16:07

Well, what can one say.

I used to own a Sony CDX600-DSP, this was a rather expensive unit at the time
i bought it. (Over half the price of my Empeg, with a 10CD changer.)

This unit had 2v line drivers, and could not drive my amps the way I wanted.
When I got my Empeg I had 4v, and for me, this was a whole new world (well, almost)

One thing I dont't like about the Empeg's sound stage, is the 'digitized computer' noise you can hear in the backgroud if you listen carefully.
I would love if this noise wasn't there, but when I think of what the Empeg really is (a little computer) I don't mind abit, just lover my amps gain control.

I truly love my Empeg, and not being any IASCA thing, I like the sound I get in
my car. (A diesel knocking VW) I like the sound I get at home too...

I would like to know what exactly ***** is complaining about......


TommyE

Posted by: dionysus

Re: Opinions on empeg sound stage - 27/06/2000 16:19

In reply to:

One thing I dont't like about the Empeg's sound stage, is the 'digitized computer' noise you can hear in the backgroud if you listen carefully.
I would love if this noise wasn't there, but when I think of what the Empeg really is (a little computer) I don't mind abit, just lover my amps gain control.


They've fixed this with the mark2's:)
-mark (no relation:) )


...proud to have owned one of the first Mark I units

Posted by: TommyE

Re: Opinions on empeg sound stage - 27/06/2000 16:25

I don't know what to do....

Keep my mkI, buy a mkII as well. (I'm in love, hate to sell it)

I'll have to eat old bread for a couple of months if I buy another one, and my girlfried, family and friends would think I am an complete idiot ........

TommyE


Posted by: rob

Re: Opinions on empeg sound stage - 27/06/2000 16:45

> the 'digitized computer' noise you can hear in the backgroud

This has been eliminated with the Mark 2 - at least, I can't hear it in the Merc demo car, and it was the first thing I listened for!

Rob


Posted by: TommyE

Re: Opinions on empeg sound stage - 27/06/2000 16:47

You know how to tempt a guy........ Eeehh...
I mean about me getting another Empeg.

TommyE

Posted by: tfabris

Re: Opinions on empeg sound stage - 27/06/2000 16:56

Tommy and Dionysus:

Although your comments are valid, they're not about the sound staging. They're about various quality, noise, and amplification issues. Perhaps I should clarify the term "sound staging".

Sound staging is the ability of a given audio product to reproduce the 3-dimensional image of the recorded instruments. Granted, the recording and mastering side of things plays a big role in this, but assuming a given "reference" recording, then different equipment will more accurately reproduce the soundstage.

The competitions use a specific recording for testing this, and the judges base their ratings on how clearly defined the instrument locations appear to be in the soundstage.

Because the soundstage is so subtle, tiny variations in equipment setup can have a large effect on the perceived soundstage. And MP3 uses a special method for compressing the stereo channels (in fact, there are some options regarding how you can control the stereo encoding of an MP3 file), which is why .WAV support is important to any discussion about sound staging with regards to the Empeg. This is why Doug "tanstaafl" Burnside is so interested in getting .WAV support into the Empeg: he competes in these competitions. I expect he'll be chiming in here pretty quickly... he's the one who told me about the way the competitions are judged.

Now I'm going to stick my neck out here and say that I don't think the head unit has very much to do with the sound staging. It's more in the speakers, amps, and the source material than it is the head unit. As long as the head unit does a correct job of turning the source data into line-level stereo output, it shouldn't matter much.

Then again, there's a whole area of audio equipment (like the Sony ES compact disc players) which are more expensive and go to extra trouble to make sure the line-level output is perfect. But some of the extra things they do sound like snake oil to me, like using an extra-stable CD transport mechanism to reduce vibrations transmitted to the disc. I mean, you can prevent skips this way, but other than that, the data is digital and the transport mechanism has nothing to do with the sound as long as the bits are there. The D/A converters are more important than the transport mechanism, and a really good D/A conversion system is vital to turning the bits into real audio waves. As I understand it, the D/A converters in the Empeg are good ones (although I don't know the technical details of all of this).

There's a good discussion of the importance of good D/A converters can be found here, and I think that any discussion of the Empeg's sound stage will have to defer to the information there about D/A conversion jitter. That's probably the one piece of the Empeg circuitry that can affect the soundstage the most, is the accuracy of the clock controlling the output of the D/A convertor.



___________
Tony Fabris
Posted by: dionysus

Re: Opinions on empeg sound stage - 27/06/2000 17:09

I agree with most of wht you say in regards to sound staging, however, I'm comparing apples to apples here..

I've had a decent system in my car ever since having gotten my new car, and to me, the sound quality was among the best. The only thing different between my setup now (well.. before I sold the empeg:) ) and my old setup is the head unit. The alpine head unit was replaced for the empeg. The empeg usually doesn't appear to be nearly as good on the upper and lower bands as the alpine was. The bass isn't as loud, and the trebble isn't as bright.

Having said that though, I think most of this can be attributed to the nature of mp3's... I've actually experimented with high-vbr mp3 files (side-by-side comparison between my alpine head unit and the empeg) - I can get the lower frequencies to be nearly indistinguishable (sp), but the trebble still sounds different - the empeg isn't as sharp, even at the highest bit rates.

I think the proper eq'ing of the empeg would fix this though, and honestly changing some of the more advanced options of the eq DO help. I'm a clutz when it comes to eq'ing though - I always fix one thing just to notice something wrong w/ a different frequency. I think that the default equalization of the alpine simply sounded better then the empeg, but that someone with more experience could make the empeg sound as good if not better then my old head unit. This is the reason that I've suggested pre-set equilizer settings in the past, I don't really trust my judgement when it comes to setting things, but I know what sounds good...

I've suggested having pre-sets before, but what about taking it to the next level.. What about having someone with alot of experience w/ sound quality test the empeg, and see how they set their eq? the Q value seems to help alot w/ the higher and lower notes, but some of us just aren't good enough to set them ourselves:)

-mark

...proud to have owned one of the first Mark I units
Posted by: tfabris

Re: Opinions on empeg sound stage - 27/06/2000 17:20

I think that the default equalization of the alpine simply sounded better then the empeg, but that someone with more experience could make the empeg sound as good if not better then my old head unit.

Which was one of my points: That many aftermarket car stereos artificially increase the bass and treble a little bit above "flat". I, too, noticed that the Empeg did not do this. Its output was much flatter than most car stereos at the default settings. You are right in that the Empeg needs some EQ tweaking before it sounds like the other stereos.

Regarding your point about bass and treble: You defininitely should notice a loss of very-high-frequency data in an MP3, but there shouldn't be any noticeable difference in the low-end stuff. The only difference there should be differences in the default EQ of the head unit's output. At least that's the way I understand MP3s to work, I don't know if that's really for sure the true case.

Anyone else experience the same thing?

___________
Tony Fabris
Posted by: dionysus

Re: Opinions on empeg sound stage - 27/06/2000 17:36

In reply to:

Regarding your point about bass and treble: You defininitely should notice a loss of very-high-frequency data in an MP3, but there shouldn't be any noticeable difference in the low-end stuff. The only difference there should be differences in the default EQ of the head unit's output. At least that's the way I understand MP3s to work, I don't know if that's really for sure the true case.


The thing is though - ever since putting in the empeg, I've felt like I've had a single 8" in the back of my car, instead of the 2 10's that I have; i've had a hard time reproducing the bass quality playing mp3 files.. I'm not speaking of loud bass - i'm speaking of clear bass... When empeg introduced the advanced Eq, this got significantly better.. (it was almost like certain frequencies didn't make the cut for my crossover with the empeg, that did with my old head unit..) changing some of the values (sorry - an't remember which, and I don't have an empeg at the moment to find out (cry) ) did improve things, but I could never be satisfied with how it sounded, especially not accross 3000 tracks... One eq setting might sound perfect for one album, but would sound very poor on another..
In a sence, owning a collection that's been compressed using every which way possible, it was very difficult for me to eq my settings in a way to accomodate my entire collection... Yes, you can have different eq settings for different types of music, but it seemed as if the alpine's defaults were always good enough (I never changed them), were as I seemed to be constatly tweaking the empeg...

-mark

...proud to have owned one of the first Mark I units

Posted by: tanstaafl.

Re: Opinions on empeg sound stage - 27/06/2000 18:43

This is why Doug "tanstaafl" Burnside is so interested in getting .WAV support into the Empeg: he competes in these competitions. I expect he'll be chiming in here pretty quickly...

Uhhh..... Yeah. What Tony said.

tanstaafl.



"There Ain't No Such Thing As A Free Lunch"
Posted by: Verement

Re: Opinions on empeg sound stage - 27/06/2000 22:18

In reply to:

I can get the lower frequencies to be nearly indistinguishable (sp), but the trebble still sounds different - the empeg isn't as sharp, even at the highest bit rates.


I have two observations to share.

First, many MP3 encoders will summarily throw out all frequency information above some threshold (typically 16kHz) regardless of bitrate. You might want to experiment with encoder settings (like LAME's -k) that avoid this cutoff.

Second, and let me preface this by saying I don't know how significant it might be in terms of what people are perceiving wrt sound stage and so forth, but I have evidence to suggest that the Xaudio MP3 decoder used in the empeg is only a limited accuracy ISO/IEC 11172-3 audio decoder. This means the reconstructed audio signal differs from a reference signal more greatly than a "full accuracy" decoder is allowed, but the difference is still within an acceptable limit (as defined in the ISO/IEC 11172-4 compliance standard.) The audibility of this difference is undoubtedly a subjective matter, but to the ears of an audiophile, the accuracy of the decoder may certainly have some influence.

-v

Posted by: xavyer

Re: Opinions on empeg sound stage - 27/06/2000 22:45

For what it's worth, I got a copy of the IASCA competition CD, ripped it, and loaded it into the empeg. Now, I'm no audiophile, so this is my subjective opinion, but I was easily able to distinguish the locations of the instruments and vocalists for all but a couple of the tracks. Those tracks which I had trouble with; I suspect, was really just my lack of 'audiophile grade' knowledge. However, in all fairness, there are instructions that come with the CD which show the general layout of the sound stage, and it's kind of hard to read the instructions without looking at the diagrams. Hence, I actually drew what I thought the sound staging was like a couple of weeks after I read the instructions. Partly due to the notion of wanting to let the prior knowledge evaporate from my memory, and partly due to procrastination; both successfully contributing to the desired result of forgeting what the diagrams looked like. For the most part, it worked, although, to be really unbiased, I should take it to one of the IASCA competitions, just to have a 'certified judge' do the listening. In the end, it's still a subjective opinion, but at least it would be 'judged' by someone who's (supposedly) done it before. (The reason I say 'supposedly' is that the IASCA people where attempting to recruit _me_ as a judge when I was picking up the CD. Go Figure.)

Posted by: teemcbee

Re: Opinions on empeg sound stage - 27/06/2000 23:40

There was nothing told about how the empeg unit was installed (thinking of the floating grounds), which compression ratio was used for the testing sound (of course 96 or 112 kbps would have poor sound quality and - as tony described - sound staging )

I think to be able to judge about the comments to the sound staging quality you must have to know something about the environment and the circumstances it's been tested.

TeeMcBee

Posted by: Henno

Re: Opinions on empeg sound stage - 28/06/2000 00:03

there's two separate levels of discussion here: The sound staging of MP3 files at various bitrates, and the sound staging.

Actually, we need to add the Eq comments as a separate discussion item too: they have nothing to di with sound stage. Thus there are actually three discussions going on at present. As this all started about sound staging, we should stick to the two issues you refer to: the ability for MP3 in general to maintain soundstage in the compressed files and the ability of the empeg to reproduce (what's left of) the soundstage in MP3.

Well, I've already given away my position in this by the comment between brackets above: I don't believe that lossy compression at the current levele of technology can preserve soundstage. When you closely listen, MP3s sound very nice, but sound different then the original when played on good equipment. Besides compression (throwing out sounds that you're supposed not to hear; thus changing the sound of the recording), I believe it also changes the timing of the signals, with jitter-like effects (which affect sound stage).As you said, the only way to separate these two items is to directly compare WAVs and MP3s on the same equipment. Unfortunately, we cannot play WAVs from the empeg players yet.

As I've said months ago, Emma sounds good: great for background music and parties, but is no comparison for close listening when compared to a well produced CD played from a jitter-free installation using the same (quality) amps, cables and speakers.

Also, most CD players make no serious attempt at all to avoid jitter, and actually I haven't seen a head unit for in-car use yet that tries to avoid it.(This is where playback equipment comes in: to avoid jitter, you can't rely on the rotational speed of the disk to extract the data at the right pace in the first place). So comparing Emma to other car heads will not be conclusive either, but can -- of course -- establish the empeg's relative place with other in-car units. This is what the ICE judge was talking about, I guess.

If someone can tell me where to get the ICE sound-stage CD (and I can get my hands on a Mark2 player), I'll do some more comparisons. Empeg delivering the WAV play-back capability will also help. But let's not fool ourselves: MP3 technology is based on a hearing model. As most other compression models iIt tries tries to compromise between file size and hearing ability with a focus on sound - not timing : there is no free lunch, you can't keep all sound effects in any lossy compression.



Henno
ex 00120
Posted by: tfabris

Re: Opinions on empeg sound stage - 28/06/2000 00:35

but I have evidence to suggest that the Xaudio MP3 decoder used in the empeg is only a limited accuracy ISO/IEC 11172-3 audio decoder.

This could be important information. Everything I've read seems to indicate that sound staging is dependent upon very subtle cues, cues that could be destroyed by something as simple as a slight jitter problem or a minor innacuracy in the decoder. My ears aren't golden enough to hear these problems, so I don't know about this for sure.

(But most importantly, if true, a problem like this could be solved with a simple software upgrade.)

What else can you tell us about this?



___________
Tony Fabris
Posted by: tfabris

Re: Opinions on empeg sound stage - 28/06/2000 00:44

we should stick to the two issues you refer to: the ability for MP3 in general to maintain soundstage in the compressed files and the ability of the empeg to reproduce (what's left of) the soundstage in MP3.

I've been thinking about it. There's one other issue to consider, too:

One school of thought might say, "because the Empeg is mainly designed to play MP3 files, you can't separate the MP3-quality issue from the empeg-hardware-quality issue. All that matters is the end result of perceived overall quality."

I mean, I'm just playing Devil's Advocate here. I see them as two totally separate issues. But we do have to acknowledge it as a valid point of view.

___________
Tony Fabris
Posted by: PaulWay

Re: Opinions on empeg sound stage - 28/06/2000 01:26

In reply to:

Then again, there's a whole area of audio equipment (like the Sony ES compact disc players) which are more expensive and go to extra trouble to make sure the line-level output is perfect. But some of the extra things they do sound like snake oil to me, like using an extra-stable CD transport mechanism to reduce vibrations transmitted to the disc. I mean, you can prevent skips this way, but other than that, the data is digital and the transport mechanism has nothing to do with the sound as long as the bits are there.


Let me start by putting this question to you. A CD-ROM can take 650MB of data, but a CD has 72 minutes of audio. 72 minutes of uncompressed stereo 16bit 44.1KHz music is 762048000 bytes, or 726.7 megabytes. So how do they fit that on there if a CD-ROM only contains 650MB?

Simple. CD Audio is stored in an error-[u]compensating[/u] format where as CD-ROM data is stored in an error-[u]correcting[/u] format. I'm not clear on the exact details, but basically the CD Audio is stored so that bit errors eventually even out - the audio will eventually get back to the correct position even if the immediate sample might be out by a least-significant-bit or two. CD-ROM data, on the other hand, is stored in an expanded format so that bit errors can be rebuilt transparently.

The point here is that CDs usually have a couple of hundred bit errors per second of play time (don't quote me on that, those statistics are coming from old memory). These bit errors are coming from fluctuations in the disc's speed and distance from the lens, scuff marks and prints, and other interference with the laser beam during playback. The playback algorithm is able to minimise the impact of those errors but sometimes it doesn't compensate completely; or, for your audiophiles, as completely as they'd like. Consider that the least-significant bit in a 16-bit sample represents about -96dB - in other words, in a 96dB signal they represent the bottom 1dB. So while ordinarily you may not hear bit, or even two- or three-bit, errors, they still exist in the audio and therefore can affect very sensitive listening devices.

Whether people's ears are 'very sensitive listening devices' is another question entirely.

The uptical pracshot of this is that some audiophiles might want to pay extra for a device which claims to have higher quality components to reduce the chance of these defects making it through to the audio stream.

Also keep in mind that these defects will affect a CD rip - the audio is [u]not[/u] coming off the disc in the same way as a file does.

Does that all make sense now?

Save the whales. Feed the hungry. Free the mallocs.

Posted by: schofiel

Re: Opinions on empeg sound stage - 28/06/2000 02:37

Well said - otherwise, with no context it is pure heresay.

Apply a context, then judge.

What the h*** is soundstaging, anyway? Someone explain please - 'cos obviously in 20 years working within one of the most heavily jargon-filled industries in the world (electronics and software engineering) I have obviously missed something critically important (Not).


One of the few remaining Mk1 owners...
Posted by: teemcbee

Re: Opinions on empeg sound stage - 28/06/2000 02:52

Tony has explained somewhere in this thread what exactly sound stage is.

TeeMcBee

Posted by: schofiel

Re: Opinions on empeg sound stage - 28/06/2000 03:33

Let me start by putting this question to you. A CD-ROM can take 650MB of data, but a CD has 72 minutes of audio. 72 minutes of uncompressed stereo 16bit 44.1KHz music is 762048000 bytes, or 726.7 megabytes. So how do they fit that on there if a CD-ROM only contains 650MB?

Simple. CD Audio is stored in an error-compensating format where as CD-ROM data is stored in an error-correcting format.


Not quite. The true capacity is around 720M, unformatted. When you apply formatting to create a structure to the disk that can be read by an OS (a CD-ROM), you end up with around 647M free space. Regardless of disk structure, you can store your data as discrete bits in a stream (giving massive bit-error rates) or as symbols within an error correction scheme in a stream (giving the same bit error rate, but a reduced number of symbol defects which can effectively be corrected to almost 100% accuracy). Hence, audio disks appear to have a relatively high capacity compared to the raw data capacity of a CD-ROM. This explains (in part) why CD-ROMs can also be cranked at higher rotational speeds to get the data back - you are not listening them, but you can also do "predictive" reads with more narrowly focussed lasers.

If you pay extra to buy "speed stabilised drive mechanics" then you have been suckered ; the drive speed could drop to zero for up to a quarter of a second (in modern audio players) without affecting the playback in the least, since the data stream from the disk drive is recognised as being unstable; as a result, it is buffered in a FIFO which feeds the data out at an accurate clock rate to the DACs. As long as the FIFO is fed, then there is no need to mute. You should be paying more for accurate, synchronised output stage clocks (aka Linn) and large FIFOs, coupled to accurate, linear, high bitcount DACs.

So while ordinarily you may not hear bit, or even two- or three-bit, errors, they still exist in the audio and therefore can affect very sensitive listening devices.

On some of the players I worked on, the lower 2 or 3 bits of output to the DAC were actually supressed after tests showed that the objective, and some subjective, listening results were made worse by the addition of this data to the output path. One of the original Philips players, the CD104, became a reference deck for many radio stations for many years, even after the introduction of supposedly superior aparatus - and this was one of the few players that had bit suppression in the output stage.

Also keep in mind that these defects will affect a CD rip - the audio is not coming off the disc in the same way as a file does.

...and here lies the problem; when you rip, you take the entire bit range off the CD as raw data before processing. This means that if you have been used to a particular reproduction standard of audio playback from a given CD drive, you will inevitably surprised by the difference in sound from a rip since the ripping software is working with different source material to your CD player in the form of extra data. You then loose some of the reconstructed spectral content in the compression, and then finally you still have to play it back through a similar reconstruction process (DAC) as the CD.

My personal experience with this process (in the form of Emma empeg and Xing software) is that I have discovered extra clarity in lyrics, and can "hear" the music better, but that I seem to have on occasions lost some definition of the stereo image. This is something I (subjectively) correct by increasing the bitrate of the MP3 or using VBR; I have switched to exclusive use of VBR for this reason, and choose to RIP pieces where stereo image and clarity (classical, for example) are important at higher rates. Not very scientific, I know, but it seems to work!

Considering that the listening environment in a car at 60 mph is not the best place to listen without dynamic range compression being applied to the music (this is assuming a noise floor that rises to give a listening dynamic of possibly only 50dB), then a discussion about the introduction of a single bit output element representing a -96dB input to the output signal is pretty irrelevant.

At home, it will be a different story, but is telling that in my case, both myself and my wife now use the empeg as the preferred music source over the CD player (through the same HiFi) because we can hear lyrics and instruments properly for the first time. Before you pile in and say "that doesn't say much for your CD player", it is one of the most expensive player units produced by Panasonic a few years back - it's now gathering dust





One of the few remaining Mk1 owners...
Posted by: altman

Re: Opinions on empeg sound stage - 28/06/2000 07:15

Actually, when I was eating lunch at the RealConference 2000 (I was in San Jose for the FCC test of the mk2) I sat next to one of the guys who worked on the XingTech VBR encoder. 10 minutes of talking to him convinced me that I really should be using VBR.

. 128, 160 and now VBR. My collection is looking seriously patchy ;)

Hugo


Posted by: altman

Re: Opinions on empeg sound stage - 28/06/2000 07:20

The Xaudio decoder is, as with almost all decoders, +- 0.5 bit (ie, the lowest bit of the output can differ from that of the frauhofer reference decoder).

This is pretty common with decoders due to optimisations and rounding - eg, winamp, etc all have the same limitations.

We wouldn't be happy shipping anything which had substandard decoding. We may well be switching to a more efficient decoder in the near future, and that also has the same accuracy.

Hugo


Posted by: teemcbee

Re: Opinions on empeg sound stage - 28/06/2000 07:32

So with a simply software upgrade you can raise the quality of sound. Every other unit would have to be replaced cause it's a leak of hardware if the quality isn't good

Will this new version be in the first customer release or can't you say that at the moment?

TeeMcBee

Posted by: Jazzwire

Re: Opinions on empeg sound stage - 28/06/2000 07:55

I can't see empeg changing the decoder engine this close to the consumer 1 release...
I imagine that it would require a large amount of testing by beta testers... =)

Jazz
(List 112, Mk2 on order. Mk1 Unit for sale S/N 00030, 4 gig blue, apply within)
Posted by: rob

Re: Opinions on empeg sound stage - 28/06/2000 08:02

The alternate decoder is already well tested and has been utilised in other projects we've undertaken. There are licencing issues before we can use it, however, and Consumer 1.0 will probably still use XAudio.

The new decoder doesn't give a quality advantage, but it's more efficient, freeing up processor time for future applications. It will also facilitate multiple CODEC's, e.g. WMA and WAV.

Rob


Posted by: Henno

Re: Opinions on empeg sound stage - 28/06/2000 08:17

you can't separate the MP3-quality issue from the empeg-hardware-quality issue. All that matters is the end result of perceived overall quality

Agree. And Emma was doing a very reasonable job when connected to a top-end system. I'm curious (as Rob is, I suppose) how much of the difference is caused by empeg as a head-unit. I'd love to compare an original CD-WAV, to an empeg-WAV on a no-compromise amplifier/speaker system and the listen to an MP3 copy using the same system.

Anyone who can help to get my hands on an ICE sound-stage CD?
Rob / Hugo, any chance on WAV support soon?

Henno
ex 00120
ready to score one of the 40
Posted by: Jazzwire

Re: Opinions on empeg sound stage - 28/06/2000 08:29

I wasn't saying the new decoder wasn't well tested, more that the beta testers have put so many hours into testing the software with the old decoder, it would be an odd move to change such a major part for the first non beta consumer release... =)

I'll shut up now... =)

Jazz
(List 112, Mk2 on order. Mk1 Unit for sale S/N 00030, 4 gig blue, apply within)
Posted by: Henno

Re: Opinions on empeg sound stage - 28/06/2000 08:37

...and here lies the problem; when you rip, you take the entire bit range off the CD as raw data before processing. This means that if you have been used to a particular reproduction standard of audio playback from a given CD drive, you will inevitably surprised by the difference in sound from a rip since the ripping software is working with different source material to your CD player in the form of extra data.

I don't understand this part, Rob. Are you saying that the ripping process uses the data that is actually on the disk, and thus is processing different sound (content) than the (error-masked) play-back of audio equipment?

Henno
ex 00120
ready to score one of the 40
Posted by: altman

Re: Opinions on empeg sound stage - 28/06/2000 09:11

No, the new software has identical output to the current stuff, it just takes less CPU time (as if we're short of it!).

It's had lots of testing as it's in some of the other OEM products already.

Hugo


Posted by: tfabris

Re: Opinions on empeg sound stage - 28/06/2000 09:51

128, 160 and now VBR. My collection is looking seriously patchy ;)

Mine, too. For a while I was satisified with 128, but that was when I was listening to the MP3s on a cheap computer soundcard. After getting the Empeg, I discovered that 128 isn't enough. The higher-quality amps and speakers in my car allowed me to hear artifacts that I didn't notice on my computer. Now I'm slowly going through my collection and re-encoding everything with the Xing VBR engine.

Incidentally, if you're switching to the Xing VBR encoder that's in AudioCatalyst, I suggest that you skip the middle bitrate setting (called "Normal") altogether and go straight for the next one up, the one called "Normal/High".

The "Normal" setting produces files that are slightly smaller than a 128kpbs file, and although the high-frequency artifacts are less frequent, there is still a slight quality loss if you listen closely on some material. If you go with "Normal/High", you get files that are slightly bigger than 128kbps files, but the quality is much better.

___________
Tony Fabris
Posted by: schofiel

Re: Opinions on empeg sound stage - 28/06/2000 09:59

No, not quite.

What comes off the disc is fed to a decoder. Small blocks of data are used to represent data, called symbols. Symbols are easier to fix than pure binary, so you can read off the disk with high error rates and yet still get all your original data back.

The symbol decoder corrects any busted symbols where possible (note!) and then decodes them into pure binary data (the original data generated during the recording process in the studio). This lot then enters the output chain of your CD player, and what part of it is actually used to create sound is up to the designer of the output chain. In two examples I know of, one had the bottom three bits chopped off each sample for each stereo channel (it's not as simple as this, by the way ) due to tests that showed this would improve the quality of the output. The other used single bit output, where the sample streams were manipulated on the fly to improve noise figures (a very expensive DSP {for 1990 that is} was needed for that one, I can tell you). Note that if a symbol is irretrievably busted, this is where the player has to act smart by either guessing what the correct value would be (it makes up a value based on trends) or simply causing the output to mute before the erroneous value is presented to the DACs. You can see that all sorts of stuff can take place in your CD's output stage before you hear it. Each player is different, as well, 'cos playback strategies on damaged symbols are formulated differently by different companies.

The difference with the data used by a RIPper is that when you RIP using a CD-ROM drive, at the point where you actually get the binary channel samples, the MP3 encoder is given data with all of the bits of each sample available. They are unmodified, and can contain uncorrected samples with error markers. With a CD player, the output stage designer may choose to correct (described above), or even modify the data word size by choice while trying to avoid the effects of signal spectrum modification in the time domain (ie. after the signal has been reconstructed). In the early days this was to compensate for non-linearity in the DACs or to cover noise. With the MP3 encoder, who knows what choices the designers have made about the content of the data stream and their strategies on damaged symbol data?

One of the few remaining Mk1 owners... #00015
Posted by: dionysus

Re: Opinions on empeg sound stage - 28/06/2000 10:25

In reply to:

Incidentally, if you're switching to the Xing VBR encoder that's in AudioCatalyst, I suggest that you skip the middle bitrate setting (called "Normal") altogether and go straight for the next one up, the one called "Normal/High".


Agreed - this is what I almost always use, and I can definately tell a difference at this stage.
-mark

...proud to have owned one of the first Mark I units

Posted by: tfabris

Re: Opinions on empeg sound stage - 28/06/2000 10:36

With the MP3 encoder, who knows what choices the designers have made about the content of the data stream and their strategies on damaged symbol data?

MP3 encoders and decoders assume that the data is undamaged. They input and output streams of 16-bit numbers, each number representing the position of the speaker cone at a given point in time. That's all. They don't try to error-compensate the audio data stream.

A properly ripped .WAV file from a CD should have no symbol errors. I agree that a .WAV file ripped from a CD will sound different than the CD audio track, but only because the DAC which plays the audio track is different than the DAC which plays the .WAV file. Not because of symbol errors.

The ideal situation would be to create your MP3s from the same original raw wave data that was used to create the CD master, bypassing the ripping process altogether. This would remove any possibility of introducing symbol errors before the MP3 encoding happens. That's one reason I like the idea of artists making their own MP3s and distributing them.

___________
Tony Fabris
Posted by: Verement

Re: Opinions on empeg sound stage - 28/06/2000 11:44

In reply to:

The Xaudio decoder is, as with almost all decoders, +- 0.5 bit (ie, the lowest bit of the output can differ from that of the frauhofer reference decoder).


The Xaudio decoder produces different output depending on platform. According to the compliance tests I have performed, the x86 version indeed passes the strictest accuracy test, but the ARM version passes only the limited accuracy test.

What do I mean?

Part 4 of ISO/IEC 11172 defines the compliance tests for MPEG audio and video. Section 2.6.3 defines the computational accuracy tests for audio decoders. It states, "To be called an ISO/IEC 11172-3 audio decoder, the decoder shall provide an output such that the rms level of the difference signal between the output of the decoder under test and the supplied reference output is less than 2^(-15)/sqrt(12) for the supplied sine sweep (20Hz-10kHz) with an amplitude of -20dB relative to full scale. In addition, the difference signal shall have a maximum absolute value of at most 2^(-14) relative to full-scale."

Then it says, "To be called a limited accuracy ISO/IEC 11172-3 audio decoder, the decoder shall provide an output for a provided test sequence such that the rms level of the difference signal between the output of the decoder under test and the supplied reference output is less than 2^(-11)/sqrt(12) for the supplied sine sweep (20Hz-10kHz) with an amplitude of -20dB relative to full scale."

The tests treat the decoder output as 24-bit signed fractional values in the range [-1, 1). In other words, the binary point is immediately after the sign bit. For the purposes of compliance testing, where only 16 bits of output are available, the remaining bits are set to zero. When I tested version 1.3.1 of the Xaudio decoder library under both x86 and ARM, here's what I found:

Xaudio 1.3.1, x86
  RMS level = 8.602 x 10^-6 (under 8.810 x 10^-6; full accuracy compliant)
  Max diff = 1.538 x 10^-5 (under 6.104 x 10^-5; full accuracy compliant)

Xaudio 1.3.1, ARM
  RMS level = 2.065 x 10^-5 (over 8.810 x 10^-6 but under 1.410 x 10^-4; limited accuracy compliant)
  Max diff = 6.580 x 10^-5 (over 6.104 x 10^-5)

As you can see, Xaudio's accuracy under ARM is worse than +- 0.5 bit; it's more like +- 2 bits, i.e., the 16-bit integer value can differ from the reference output by as much as 4 in either direction.

I'd be happy to share the Perl scripts I used to calculate these. The bitstreams and reference output used for compliance testing can be found here.

I'm curious; what decoder are you considering switching to?

-v

Posted by: Henno

Re: Opinions on empeg sound stage - 28/06/2000 12:09

I'm ... re-encoding everything ... VBR.
go straight to ... "Normal/High"


Yup, came to the very same conclusions very early in the game. Have everything encoded at Normal/High with VBR; some 17GB worth !

Henno
ex 00120
ready to score one of the 40
Posted by: TommyE

Re: Opinions on empeg sound stage - 28/06/2000 13:08

Hmm, and I started out talking about 2v on my Sony compared to 4volt on my Empeg. :):)

I didn't understand much, but it sounds good.

TommyE

TommyE

Posted by: tfabris

Re: Opinions on empeg sound stage - 28/06/2000 14:14

This fascinates me tremendously. I'm dying to see what Mike and Hugo have to say about this.

___________
Tony Fabris
Posted by: tanstaafl.

Re: Opinions on empeg sound stage - 28/06/2000 16:28

Henno --

Go here: http://www.iasca.com/ and choose the "Iasca Store" link. This is the CD that is used for all judging in IASCA competitions, complete with diagrams showing the sound stage and a host of technical tracks.

Enjoy!

tanstaafl.

"There Ain't No Such Thing As A Free Lunch"
Posted by: bonzi

Re: Opinions on empeg sound stage - 28/06/2000 23:55

Also, most CD players make no serious attempt at all to avoid jitter, and actually I haven't seen a head unit for in-car use yet that tries to avoid it. (This is where playback equipment comes in: to avoid jitter, you can't rely on the rotational speed of the disk to extract the data at the right pace in the first place).

Of course one cannot rely on CD transport rotational speed for timing reference, but, unless I am very much mistaken, nobody does. AFAIK, the thing works the other way around: timing reference is provided by a (hopefully stable) clock that paces DAC, and if FIFO feeding the DAC starts emptying too quickly, the drive servo gets instructed to spin a bit faster. Now, if you make the FIFO magasample or so deep, you get skip protection as found on portables or ICE units. In any case, no need for acoustic isolation nonsense in imitation of analog turntables.

Just my ~ 0.17 HRK :)




Dragi "Bonzi" Raos
Zagreb, Croatia
#5196
Posted by: phaigh

Re: Opinions on empeg sound stage - 29/06/2000 13:24

If you pay extra to buy "speed stabilised drive mechanics" then you have been suckered ; the drive speed could drop to zero for up to a quarter of a second (in modern audio players) without affecting the playback in the least, since the data stream from the disk drive is recognised as being unstable; as a result, it is buffered in a FIFO which feeds the data out at an accurate clock rate to the DACs. As long as the FIFO is fed, then there is no need to mute. You should be paying more for accurate, synchronised output stage clocks (aka Linn) and large FIFOs, coupled to accurate, linear, high bitcount DACs.

So how come that when I add an isolation pad to my CD player (and amp) the music sounds significantly better then?

I recently came into some money and bought a new home system (Arcam FMJ series, as it happens) and a 70ukp isolation pad gave the music a significantly better sound stage (in the pure sense) and a much greater range.

I don't see why, apart from the noise from travelling at 60mph, this sort of extra isolation couldn't be added to a car stereo.

As far as I can see:

Better laser precision = better reproduction of the audio stream.

?

Cheers,

Paul

Paul Haigh, 6GB, Blue
Reg: 4120 - Serial 00254
Posted by: tfabris

Re: Opinions on empeg sound stage - 29/06/2000 14:08

So how come that when I add an isolation pad to my CD player (and amp) the music sounds significantly better then? (...) As far as I can see: Better laser precision = better reproduction of the audio stream.

No, because the laser on a CD player is not analagous to the needle on a record player. The laser has nothing to do with the audio quality.

As long as the laser is able to extract the data from the CD without errors, it doesn't matter how precise or suceptible to vibration it is. That's the whole point of a digital audio system: The responsibility for sound reproduction lies with the DACs and the amplifiers, not the transport mechanism.

Now, I will grant that if the laser is getting errors when it extracts the data, your sound will suffer. But unless something is radically wrong with your CD player or the CDs you're playing, they shouldn't be getting any errors at all. And when they do get errors, they'll manifest themselves as things like skips, not as soundstaging problems.

If adding your special "isolation pad" genuinely improved the sound, then I suggest that there was something else wrong with your system which was causing other problems. Perhaps a ground loop between the CD player and the amplifier, or a loose wire which got reconnected better as a result of you moving the components to insert the isolation pad. But simply preventing vibrations from reaching the CD player shouldn't have any effect on the sound as long as the data is still being read off the CD without skips. A CD player is not a turntable, and there is no need to isolate it.

I submit to you that in a proper, randomized, double-blind test, you wouldn't be able to tell the difference between the presence or absence of the isolation pad.

___________
Tony Fabris
Posted by: altman

Re: Opinions on empeg sound stage - 29/06/2000 14:51

What gets my goat particularly are the audiophiles to claim to tell the difference between *digital* interconnects, and advise you spend a pile on special cored gold cables for your SP/DIF runs.

I mean. 1.6Mbit. 50cm usually. I can do 100mbit over 100m with plain unshielded twisted pair cable and get no errors. And they claim to tell the difference with 50cm of coax? Errrrr.... no.

Hugo


Posted by: n6mod

Re: Opinions on empeg sound stage - 29/06/2000 16:19

This brings up an interesting experiment we tried some time ago. I didn't really think anything of it at the time, but since we're discussing it.

We tried an A/B test between the empeg MkI and an obscenely expensive Krell CD player. The rest of the system was high-end stuff as well: Balanced Audio Labs preamp, some Glow-FET amplifier (eight 6550s, this was not a single ended triode ;), and Thiel speakers.

The test track was Mummer's Dance by Lorenna McKinnett, and the empeg was playing a file encoded by AudioCatalyst (Mac) at either 160kbps or Normal/High VBR, I don't remember.

Aside from the expected loss of clarity at the high end, we noticed something truly bizarre with the soundstage.

From CD, Lorenna's voice was nearly centered left/right, and seemed to be emanating from a point about 2 feet above the floor. From the empeg, it was about 4 feet higher.

Being engineer types, we spent a little while trying to figure out what could possibly change in the audio signal that could cause a change in the apparent _height_ of a voice. Can any of you audiophiles shed some light on this one?

-Zandr, Mk.II order confirmation in hand....and I'm keeping my Mk. I. ;)

-Zandr
Mk.I #150
Posted by: altman

Re: Opinions on empeg sound stage - 29/06/2000 16:28

Hmm.

If I was a marketing type, I'd be dreaming up ad copy from this sort of thing:

empeg - makes your music fly(*)

(*) Actual altitude gain depends on encoding. Average gain 4 feet (enough to lie under madonna if desired. Not recommended for the end of operas).

Hugo ;)



Posted by: tfabris

Re: Opinions on empeg sound stage - 29/06/2000 16:31

Being engineer types, we spent a little while trying to figure out what could possibly change in the audio signal that could cause a change in the apparent _height_ of a voice. Can any of you audiophiles shed some light on this one?

It sounds like you're the only one who's actually done a direct A/B comparison and listened for soundstaging changes. My take is that a difference in frequency response might explain it. As you noted, MP3 discards ultra high frequency data. I'd love to see the same A/B test done with a straight .WAV file.

___________
Tony Fabris
Posted by: tfabris

Re: Opinions on empeg sound stage - 29/06/2000 16:33

Average gain 4 feet (enough to lie under madonna if desired.*

* even with the cone-breast costume from the "open your heart" video.

___________
Tony Fabris
Posted by: PaulWay

Re: Opinions on empeg sound stage - 29/06/2000 22:14

In reply to:

Being engineer types, we spent a little while trying to figure out what could possibly change in the audio signal that could cause a change in the apparent _height_ of a voice. Can any of you audiophiles shed some light on this one?


I'll chime in on this one. The reason, simply, is that your ears are not round.

The main theory of why a persons ears have all the little dents and whorls and are generally asymmetrical is to do with the person's ability to locate a sound in space. The shape of the ear affects the way sound enters the ear - sound from behind you generally loses some of its high frequency components. Normally, you can tell where a sound is coming from in the horizontal plane by a combination of phase changes, timing changes, and frequency and volume alterations (as the sound travels around your head, for example). Positioning a sound in the vertical plane is done by associating various frequency responses with various 'heights'.

Now, the frequency response graph is an arcane thing, but generally, for instance, sounds coming from behind and below lose more of their high frequency components. Therefore, all other things being equal, something with boosted trebles sounds like it's coming from above. If the MP3 recording had some treble distortion, which in other points in this thread has been pointed out to be the case, it might simulate this effect.

That's my guess, anyway.

Save the whales. Feed the hungry. Free the mallocs.

Posted by: schofiel

Re: Opinions on empeg sound stage - 30/06/2000 02:11



One of the few remaining Mk1 owners... #00015
Posted by: phaigh

Re: Opinions on empeg sound stage - 30/06/2000 02:39

I hear what you are saying. I was very sceptical at the time too.

However, this was done (not quite as sa double-blind) blind: the audio guy didn't tell us if he had added the isolation pad or not.

Both myself and my girlfriend could tell the difference in the audio shop and also at home.

Now I admit that I may now be biased based on the fact that I did buy the pads (although he ended up giving them to me for free - long story), but I'm willing to stake my reputation (not that I've got any) that for some reason the isolation pads did improve the sound stage and range.

I'm no audiophile (but trying), but I definitely know what I heard.

The CD and Amp were brand new (i.e. out of the box the day before) and had been on for 24hrs+ (so the power supplies /DAC were settled too).

Perhaps by adding the pads we were altering some cabling but we repeated the excercise a number of times (more than half a dozen), every time with the same result - better sound stage and range from the isolation pad, so this seems an unlikely result from anything which is transient.

The audio guy mentioned about some theory papers that had been written on the subject, so I'll give him a call and see if he can dig them out.

Cheers,

Paul.

Paul Haigh, 6GB, Blue
Reg: 4120 - Serial 00254
Posted by: schofiel

Re: Opinions on empeg sound stage - 30/06/2000 03:03

So how come that when I add an isolation pad to my CD player (and amp) the music sounds significantly better then?

To be honest, absolutely no idea - but there is no mechanical decoupling provided by an isolation pad to the laser platform whatsoever. Isolation pads are used for turntables or speakers, since they have mechano-acoutic componentry. The CD player does not have any.

Even were a laser head susceptible to harmonic vibration (and they are not, even the cheap ones, as they are *carefully* designed to stop this), this would only affect the laser's ability to track (side to side) and focus (up and down). Both of these effects are corrected in CD players, so even under the worst mechanical conditions, the error rate reading symbols does not go up very much. Don't forget, you are not using a mechanical interface reading "individual data bits" (record player, although this is a pretty bad analogy), you are using light to read "lumps of data" (CD player).

It is easy to glue a broken pot back together from the pieces since you have indications of the form of the object before it was broken, just by observation. If, however, the pot was smashed and then ground to dust, it would be impossible to reconstruct it accurately since there is less indication of the original form (the "grain" of the pieces is far smaller).

So even if your player was vibrating at the resonant frequency of one vital component of the laser focus unit (they are designed so that each subsystem vibrates at a different frequency that doesn't overlap with another component's resonant frequency), then only one aspect of it's performance (say, it's ability to focus) is affected. Immediately, dynamic compensation to correct it comes into play to try and bring down the change in error rates that are detected. Even if this doesn't work, there's still error correction of the damaged symbols going on ("reconstructing the pot"). Even if this correction doesn't work, there's still interpolation going on to "guess" what the music should have been doing. If all that goes wrong, then the player (usually) just mutes the output for a split second.

So as you can see, it's actually pretty damn hard to get a mechanical effect on the playback of the CD player, short of giving it a really good thump and putting the laser playback head off track for longer than about 220ms, or well beyond the designed mechanical operational range of one axis of the head.

For you to say that an isolation pad has improved the quality of playback, I would be inclined to say that in installing the pad, you have rectified a mechanical or electrical problem elsewhere in the interconnection of your system's units. I would also be be personally inclined not to trust the guy who sold you the pad specifically for this purpose (especially at 70 quid) since it is utterly unsuited for what he purports. Stick it under your Linn Sonndek, your vinyl will sound much better (mind you, if it's a Sonndek, it probably won't need it ). Having read your post again, it looks as if you have bought a complete system with new components. Are you sure the change in sound quality is not simply due to the fact you now have (overall) a much better system than your original?

From my own experience, the greatest influences on playback errors of a CD are in the mastering and stamping process of the factory producing the disks in bulk. I worked on a disk QA system in the 80's that measured the error rate and distribution (see this post) which allowed them to work out the rate of stamper wear. As the stampers are used, they are "plucked" and "stuffed" by the disk material they are stamping. They get clogged up or loose definition, and have to be cleaned. After a while, they wear out and are replaced. "Worn Out" means that the stamper is creating more than a certain rate and density of critical errors on playback of the disks they create. The most critical problems relate to tracking (side to side movement to follow the tracks). As long as the laser stays on track then focus errors caused by a dirty disk or disk warps (or whatever) are easier to deal with, 'cos you are still getting data. If you completely loose tracking, then you loose your data source and kablooey, it's the end of the game (click)



One of the few remaining Mk1 owners... #00015
Posted by: schofiel

Re: Opinions on empeg sound stage - 30/06/2000 03:12

I'm begining to notice a dangerous trend here, Hugo - first the "What Men Really Think" advert from AdCritic, descriptions of Madonna, ideas about being sandwiched between young female starlets, a high proportion of young female-sourced music on the director's empeg.....

Cold filtered beer sex pizza computers cars sex money sex jolt cola geek toys sex football sex linux pizza pub sex, anyone?

Exactly. Just what I was thinking

One of the few remaining Mk1 owners... #00015
Posted by: Henno

Re: Opinions on empeg sound stage - 30/06/2000 09:08

I hear what you are saying. I was very sceptical at the time too.
(italics are mine).


I know what you mean Paul. Until my enthousiastic high-end shop owner demonstrated that even the type of connects he used to link speakers to the speaker wire make a difference (he replaced the banana plugs with spades). I know that electrically this hardly makes sense, but hearing is believing: the little things like a proper audio rack, placement of components, the inter-connects used, all make a noticeable even when die hard engineers claim that there can't be any difference because they can't measure it (yet ??). Until they try for themselves, and listen, they will remain as sceptical as you (and I) were.

Henno
ex 00120
ready to score one of the 40
Posted by: tfabris

Re: Opinions on empeg sound stage - 30/06/2000 09:31

Until my enthousiastic high-end shop owner demonstrated that even the type of connects he used to link speakers to the speaker wire make a difference (he replaced the banana plugs with spades).

I'm not saying I'm skeptical of things like proper interconnects in analog gear, especially in your particular example. It makes perfect sense that the more solid the connection of the speakers to the amp, the more accurate the sound will be. This is well known in all audio circles, not just home and car audio. I've done a bit of work with sound support for live rock 'n roll performances, and I know how important things like wire gauge and good plugs can be in preventing problems. In fact, invariably, the interconnects are always the weak link in the chain and are the first things you check when something goes wrong.

But that's all talking about things which carry the actual analog signal of the sound.

What I'm skeptical about is that a vibration-damping pad under a CD player can improve the soundstage. Unless there is something wrong with the CD player which the pad corrects (or unless you set the CD player directly atop a subwoofer or directly in front of your speakers), then there should be absolutely no difference in the digital bytes which reach the DACs, whether the pad is present or not. The only thing that matters are: (a) that the bytes reach the DACs undamaged, (b) how good the DACs are at turning the bytes into analog signals, and (c) what happens to the analog signal after the DACs are done making it.

(Side note: I'm enjoying our little debate here, and it seems to be staying pretty civilized. I hope that the fact some of us disagree on this point isn't a problem, because I really respect the minds and opinions of everyone participating.)

___________
Tony Fabris
Posted by: TommyE

Re: Opinions on empeg sound stage - 30/06/2000 11:51

I must say I agree with you Tony. /me to can't see how padding is supposed to
help the audio quality. Also as Hugo pointed out, can't see how people can tell
the difference on audio fed thru cables digitally.

Audio , pictures, text whatever we see it everyday on our computers, good thing they're not that picky........... :)

TommyE

Posted by: tfabris

Re: Opinions on empeg sound stage - 30/06/2000 13:46

/me to can't see how padding is supposed to help the audio quality.

I can see how padding is supposed to help the audio quality, but I can't see how it does.

The argument for the padding goes something like this:

Once upon a time, audiophiles listened to everything on vinyl LPs. These had a very sensitive method for extracting the analog data from the groove, and acoustic and vibration isolation was important. Isolating the turntable could improve the sound in subtle ways. Companies made money by selling these things. All was well.

Then CDs came out and turntables became useless practically overnight.

So the companies said to themselves, "Well, CDs are a lot like turntables, except they use a laser instead of a needle. So what's good for the goose must logically be good for the gander, and we'll re-mark our products for CD-player owners."

That's the argument anyway. I'll leave it to the rest of you to figure out what the companies really said to themselves...

___________
Tony Fabris
Posted by: bonzi

Re: Opinions on empeg sound stage - 30/06/2000 14:50

Nice explanation, Paul. We have covered MP3 encoders' frequency response here quite extensively. What do we know about phase distortion introduced by MP3 encoding/decoding?

Dragi "Bonzi" Raos
Zagreb, Croatia
#5196
Posted by: phaigh

Re: Opinions on empeg sound stage - 01/07/2000 02:01

Okay, so consider this:

The isolation pad may not be improving the digital data from the CD itself, but all of the other components (power supply, etc) between the laser and the audio output.

I can see your thinking and I'm definitely believing my ears (since I have to trust them ) so perhaps the CD laser isn't what is helped.

I also found a url of a review of some isolation pads:

http://www.soundstage.com/revequip/steve06.htm

and here:

http://www.soundstage.com/revequip/db07.htm

Enjoy!

Paul.

Paul Haigh, 6GB, Blue
Reg: 4120 - Serial 00254
Posted by: Henno

Re: Opinions on empeg sound stage - 01/07/2000 02:31



Henno
ex 00120
did score one of the 40
Posted by: steve

Re: Opinions on empeg sound stage - 01/07/2000 02:44

>They've fixed this with the mark2's:) (digital noise)

Just checked. Bloody hell, they have. Completely. Player on pause, amp on the end stop, and silence. Given how little time I spent listening to my Mk I play silence at full gain, it's not going to make a lot of difference, but it's nice that it's gone.
(Anyway, all you sound obsessives want to get yourselves a proper car to put it in.. finally found a picture of one of the cars I run the Mk I in, see if this works...)

Posted by: muzza

Re: Opinions on empeg sound stage - 01/07/2000 03:40

Problems with attachments unfortunately

____________________________
Murray
Posted by: muzza

Re: Opinions on empeg sound stage - 01/07/2000 04:49

I have to say that I am quite happy with the sound stage I have in my car. I first put in an Alpine CD before my Empeg arrived , and still have it with the Empeg now. It worked a treat and I did a listening test a while ago using the same track on MP3 and CD.
I could hear a difference in tone, subtle, but still different. I do prefer tracks off the Empeg though. for one they are normalized better to my system. (please don't start that debate here, I just like to have them normalized to 95%-98%).
All my tracks have been Ripped with Audio Catalyst, with occational tag edits by MP3 studio. Thanks tfabris, It's a great find.

I enjoy good quality audio but haven't found any reson to go with oxygen free cables, gold plated connecters and solder every joint. But then neither have most studios which create the music we listen to.

I concur that the only real way of finding the better system is to play WAVs from the Empeg.



____________________________
Murray
Posted by: steve

Re: Opinions on empeg sound stage (way off-topic) - 01/07/2000 05:51

>Problems with attachments unfortunately

Oh well. It's also at http://www.race-cars.com/carsold/other/ffsx01/ffsx01pa.htm , but with older graphics...

steve



Posted by: Alan

Re: Opinions on empeg sound stage - 01/07/2000 07:45

In reply to:

(Anyway, all you sound obsessives want to get yourselves a proper car to put it in.. finally found a picture of one of the cars I run the Mk I in, see if this works...)


That's a nice looking car, is it street legal?

Alan





Posted by: tfabris

Re: Opinions on empeg sound stage - 01/07/2000 09:44

The isolation pad may not be improving the digital data from the CD itself, but all of the other components (power supply, etc) between the laser and the audio output.

Which I'd grant, if the components were something like a tube amplifier. I could see how transient vibrations could affect a vacuum tube. But everything inside a CD player is solid-state.

I could also see how mechanical isolation could prevent ground loops between pieces of equipment. Or how additional physical distance might prevent electromagnetic interference. But in both of those cases, there would have to be something wrong with components in order for an isolation system to be of any help at all.

I also found a url of a review of some isolation pads

I read those, and in neither case did the reviewer do a blind comparison.

Here is a fairly straightforward article on the need for blind testing in subjective tests. Without a blind test, you're opening yourself up to the possibility of subjective validation, wishful/selective thinking, etc. No matter how hard you try to be objective during such a test, if you know the expected outcome then you're going to have a tendency to fool yourself into thinking the evidence is there.

The soundstage of an audio recording is a very subtle thing. Almost as subtle as the dowsing example given in that article. The difference is that there are known factors which affect the soundstage of an audio recording and they can be reproduced in controlled tests.

It would be fairly easy to design a protocol that would blind-test the isolation hypothesis:

1) The protocol requires two people: an audiophile willing to take the test, and a tester willing to administer the test. (This is a simplified protocol which assumes both the tester and the testee want to be honest about it. If things were more serious, you'd need to verify that the tester and the testee aren't in cahoots, you'd need independent judges, you'd need to make it double-blind, etc.)

2) Agree on a reference recording- a specific passage of a specific recording where the soundstage is assumed to improve with isolation. Make sure the audiophile agrees that the passage is a correct one with which to determine the soundstage. It should be a fairly short passage, since you're going to have to run through it a bunch of times. I'd say no more than 30 seconds or so, unless the audiophile says he really needs a longer reference passage. Ideally, it would help if there were an easy way to cue up the exact beginning and end of the passage on the test equipment.

3) Visually isolate the equipment rack from the audiophile. Such as placing a partition between the audiophile and the rack. Make sure no mirrors, glass, chrome reflections, or shadows can give away what the tester is doing behind the partition.

4) Test the speakers and the listening position to make sure the audiophile agrees that they accurately represent the soundstage.

5) Agree on the number of tests to run. I know little about statistics, but for argument's sake, let's say that thirty runs would be enough. You would also agree on a number of "hits" that would constitute a positive outcome. If the difference between padding and not padding is as striking and unmistakable as you say it is, there should be an incredibly high number of hits: I'd say at least 25 out of 30. I don't know the formula for determining what would be expected due to chance, though, you'd have to look that up in a statistic textbook. I'd guess that anything under 22 would be chance, and 23-24 would be inconclusive.

6) The tester and the audiophile both have a piece of paper and a pen. The tester stands behind the partition where the audiophile cannot see. The tester calls out the number of which test run it's going to be, for instance, "This will be test number five". Both the tester and the audiophile write down the number. From this point on, the tester does not say a word or make any other noises.

7) The tester flips a coin. Heads=padded, Tails=unpadded. It is important that this coin flip happen AFTER the tester calls out the test number so that no voice inflection cues are given. Before doing anything else, the tester writes down next to the number whether it's supposed to be padded or unpadded.

8) Regardless of the outcome, the tester fidgets with the equipment so that the audiophile can't tell whether the tester is adding or removing the pad. (Here is a place where the tester could give unconscious clues if they weren't careful or if there were some kind of collusion between tester and testee- I don't know how to solve this one without significantly complicating the protocol.) The tester either places the pad under the CD player or removes it, as dictated by the coin flip. Absolutely no other changes are made to the equipment except the removal or addition of the isolation pad. Not even volume changes.

9) Without saying another word, the tester plays the test passage. After the test passage is done playing, the audiophile writes down his guess next to the number on his piece of paper. He calls out to the tester "Ready" once he's done recording his answer.

10) The tester calls out the next test number, flips the coin, etc. etc. for thirty runs.

11) At the end of thirty runs, the two pieces of paper are compared. Total the number of "hits" with "misses".


Now, to get this thread back on topic: A nearly identical protocol could be used for testing the Empeg's sound stage in comparison with a CD player. You would have to be extremely careful to compensate for differences in equalization between the two units. For instance, when I hooked up my Empeg to my home stereo, it's EQ curve when "flat" was significantly different than my CD player's. You'd probably need some frequency-test equipment to sort that out. But once it was done, then the test itself would be even easier since you could just use an A/B switchbox, or two different input channels on the amplifier.


___________
Tony Fabris
Posted by: tfabris

Re: Opinions on empeg sound stage - 01/07/2000 09:55

I left out one step in that protocol. Before the test starts, you have to play the test passage a couple of times both with and without the pad, but with the audiophile's knowledge. Once the audiophile agrees that he can hear a difference and that the test is working, then you can move on to the blind part of the test. All parties have to agree and be sure that the test is valid before you actually perform the test. If you don't, then the testee could come up with an after-the-fact excuse as to why he failed the test.

___________
Tony Fabris
Posted by: steve

Re: Opinions on empeg sound stage - 01/07/2000 12:56

> That's a nice looking car, is it street legal?

But of course :) It was my only (working...) car last year - drove it 400 miles a week, rain or shine - wet arse, big grins.
There's _nothing_ in the world like blasting open-topped through the English countryside at 5am, mid summer, dawn breaking, mist rising, empeg playing. Happiness overload.
Not tried the empeg on the track (yet).

Steve



Posted by: steveb

Re: Opinions on empeg sound stage - 01/07/2000 23:42

The isolation pad may not be improving the digital data from the CD itself, but all of the other components (power supply, etc) between the laser and the audio output.

Yep, I agree. No matter how good the bits are going to the DAC, the Digital to Analog Converter produces Analog. Every DAC i've ever seen has seperate power and ground for the analog and digital sides. Good DACs (like in CD players) provide massively excellent isolation between these two sides. However that does not prevent the circuit designer from allowing some noise to seep into the analog portion from the outside. Now, any good analog chip (DAC, OpAmp, etc.) also provide amazing noise rejection from the power supplies. None the less, I believe he said the sound staging improves, not that he could hear lots of noise in the audio. I submit that it could be that a TINY amount of noise is getting into the analog side of things and thereby clouding the subtle high frequencies that the ear uses to locate a sound. I bet that the noise is comming from whatever the CD player sits on (without the pad) and enters through the feet of the CD player. The pad is probably just providing electrical isolation.

It's just a guess, but could be easily tested by placing a piece of foil under the pad and wrapping it around to the top side and then setting the player on top. I doubt the the foil would greatly affect the mechanical properties of the pad, while providing a nice electrical path similar to the CD player without the pad. You could just use a single wire, but that's not quite the same.

Steve





Posted by: Henno

Re: Opinions on empeg sound stage - 02/07/2000 03:16

The soundstage of an audio recording is a very subtle thing.

Absolutely. Just think about it: in proper soundstage 'images' can be located a close as one foot apart! Our ears (and brain) interpret this from the tiny differences in delays between sounds reaching our left and right ears. Even at the speed of sound (as opposed to the speed of light , these time differences must be extremely small (I don't have a calculator ready: maybe someone with more Physics 101 than I have, could calculate the difference).

If one wants proof if mechanical isolation from a mat as used by Paul does make a difference, it is essential that the play-back chain is capable to maintain these subtle timing differences: it's time accuracy needs to be higher than the differences induced by properly isolating the player (and/or D/A converter; pre-amp; amp; speakers; etc). Therefore, one needs a pretty decent system to detect the effects that Paul's ears have heard. Thus, in order to do a blind test, one also needs to define the playback chain, and set-up.

Also, some equipment (especially higher-end stuff) has been built to minimise mechanical feed-back.Thus ideally one needs a good player that is poorly isolated. The magazine Stereo (Germany - April 2000) did something like this when they published a series modifications to a Sony CDP-XA7 player. I can't remember all the details, but besides improving the power supply they changed the player's feet, placed it on a heavy slate of stone, and added a load of bitumen padding to the inside of the box. This caused it to play like devices many times its costs.

Of course, all of this is pretty meaningless to the empeg discussion: empeg is not a CD-player; MP3 is not WAV; and in-car amps, speakers and wiring, together with the difficult environment (noise, electrical noise, lack of space, odd shape, variety of reflection/absorption) will induce so many other artifacts, that it will hardly be worthwhile to place Emma (or Mark) on Paul's mat .



NB: there is also evidence that compression changes the timing of recordings: immedeately prior to a transient there is a kind of pre-echo that in effect announces the transient's imminent arrival.

HiFi News / Record Review (from the UK) did articles on this in May and June. They used the clacky sound of a castagnet to compare the timing eight codecs in including Dolby Digital,MP2, MP3, TAC and MS-Audio. MP3 (at 128 bps) started to announce the clack some 10 milliseconds early. MP2 at 128 kbp is more accurate (pre-echo at 4 milliseconds), just as Dolby Digital at 128 kbps; MS-Audio started as early as -20 milliseconds; TAC was the earlies at -50.

This may indicate that some of the loss in soundstage is not due to the empeg, but caused by MP3 technology.

Henno
ex 00120
did score one of the 40
Posted by: PaulWay

Re: Opinions on empeg sound stage - 02/07/2000 07:16

Just have to share this story of CD isolation with you.

I was at my old girlfriend's house and she was complaining about having to replace her CD player. I said, "What's wrong with it?"

"It keeps skipping, but only on some CDs." Naturally, testing those CDs on other players proves the CDs are OK.

So we test it out. She puts on Nine Inch Nails and we sit back. After only a few seconds of "Closer to God", the CD player is skipping and having a lot of trouble.

I stand up, and lift the CD player off the speaker on which it had been resting. Suddenly the skipping stopped. No big surprise to find out that the pieces on which it had been skipping were the loud ones...

But would an 'isolation pad' have been useful?

Save the whales. Feed the hungry. Free the mallocs.
Posted by: phaigh

Re: Opinions on empeg sound stage - 02/07/2000 08:42

Okay, I'll take the bait.

I'll set something up with my g/f with me looking the opposite way to the system.

Watch this space.....

Paul.

Paul Haigh, 6GB, Blue
Reg: 4120 - Serial 00254
Posted by: Alan

Re: Opinions on empeg sound stage - 02/07/2000 08:48

In reply to:

But would an 'isolation pad' have been useful?


No, a verbal explanation of why not to sit it on a speaker would suffice.


Posted by: tfabris

Re: Opinions on empeg sound stage - 02/07/2000 10:58

I stand up, and lift the CD player off the speaker on which it had been resting. Suddenly the skipping stopped. No big surprise to find out that the pieces on which it had been skipping were the loud ones...

Cute story. Has nothing to do with an isolation pad improving the soundstage though. Like I said, transient vibrations which reach the CD player will manifest themselves as skips, not as soundstaging problems.

___________
Tony Fabris
Posted by: tfabris

Re: Opinions on empeg sound stage - 02/07/2000 11:07

MP3 (at 128 bps) started to announce the clack some 10 milliseconds early.

10 milliseconds is an eternity in audio terms. That's insane.

This may indicate that some of the loss in soundstage is not due to the empeg, but caused by MP3 technology.

"May indicate"? If those numbers are accurate, you don't even need to test the soundstage. There's no question it's been completely obliterated at that point.

My only question is:

Did "HiFi News / Record Review" test other bitrates besides 128kbps? I wouldn't have expected the soundstage to be anywhere close to preserved at 128kbps anyway, but I'm curious about other bit rates.

___________
Tony Fabris
Posted by: tfabris

Re: Opinions on empeg sound stage - 02/07/2000 11:10

I'll set something up with my g/f with me looking the opposite way to the system.

Cool, but wouldn't facing the opposite direction ruin the perception of the soundstage?

___________
Tony Fabris
Posted by: phaigh

Re: Opinions on empeg sound stage - 02/07/2000 11:54

Well, it should just reverse it. I'm mainly looking for if I can hear the difference - i.e. does the isolator pad make any difference.

Besides with the setup I've got (and no barriers bar sheets) this is the best way to ensure that I cannot tell wether the isolator works or not.

We've set it up, so I should have some results by tomorrow.

Watch this space!

Paul.

Paul Haigh, 6GB, Blue
Reg: 4120 - Serial 00254
Posted by: phaigh

Re: Opinions on empeg sound stage - 03/07/2000 13:37

Okay the results of the jury are in:

Raw statistics (of thirty runs)

(as determined by a coin throw):
17 with isolator
13 without isolator

Actual noticed results:
21 correct answers
9 incorrect answers (4 of which were thinking there was an isolated when there wasn't - 5 thinking that there wasn't an isolator when there was).

Song used: first 30 seconds of Porcelain by Moby (an awesome track, but I don't think that I'll ever be able to listen to it again!).

Enough said, I'm knackered!

Comments please....

cheers,

Paul.


Paul Haigh, 6GB, Blue
Reg: 4120 - Serial 00254
Posted by: tfabris

Re: Opinions on empeg sound stage - 03/07/2000 14:53

Cool! I'm impressed!

Like I said, I don't know the mathematical basis for determining what one would expect by chance. In my previous post, I pulled some numbers out of the air, but I don't know if they were the right ones to go by.

Anyone know anything about statistics and random sampling? Out of 30 random runs, is a 21-9 ratio (slightly better than 1/3) significant or not?

More importantly, though: How do you feel about the isolator now? After listening carefully to the same track 30 times in a row, and after 9 incorrect guesses (split evenly between the two possible guesses), do you still think there's a difference?

Oh, and out of curiosity, how long did it take you to go through it all?

___________
Tony Fabris
Posted by: TommyE

Re: Opinions on empeg sound stage - 04/07/2000 01:59

Hmmm

Just thought.

Is it me that has poor ears, basic electronics knowledge -> (ie. understands that equipment can be interfered), dont't think that this interference is 'enough' to 'destroy' the sound. Or is it that someone has so much better ears, and have listened much more criticaly to sound all their lifes, and they have a much more indepth knowledge of electronics/sound than me (and others) have???

(Not trying to be a smarta** here, just a very 'deep' thought) :)

I guess this subject must be very subjective, because when some people I know
claim to hear the difference on signalcables, I can't.


Cool test anyway.

TommyE

Posted by: tfabris

Re: Opinions on empeg sound stage - 04/07/2000 09:40

...dont't think that this interference is 'enough' to 'destroy' the sound. Or is it that someone has so much better ears, and have listened much more criticaly to sound all their lifes, and they have a much more indepth knowledge of electronics/sound than me (and others) have?

Right, there's a word for those people: "Audiophiles".

Practically any interference at all in the audio signal is enough to 'destroy' the sound for an audiophile. My contention was that mechanically isolating a CD player's casing didn't do anything to prevent interference because there isn't any interference to prevent in that particular instance.

___________
Tony Fabris
Posted by: phaigh

Re: Opinions on empeg sound stage - 04/07/2000 13:45

Cool! I'm impressed!

So am I!

Like I said, I don't know the mathematical basis for determining what one would expect by chance. In my previous post, I pulled some numbers out of the air, but I don't know if they were the right ones to go by.

Anyone know anything about statistics and random sampling? Out of 30 random runs, is a 21-9 ratio (slightly better than 1/3) significant or not?


I really hope so!


More importantly, though: How do you feel about the isolator now? After listening carefully to the same track 30 times in a row, and after 9 incorrect guesses (split evenly between the two possible guesses), do you still think there's a difference?

I can safely say that I'm sick to death of that song now - every time I hear it I get goosebumps! I still believe in the isolator pads to still use them, given that I could tell the difference in the majority of cases (70%). The amount of times I get to listen to music though, (i.e. in a quiet environment) is limited although I'm still quite lucky in that respect (no kids!).

I'd definitely recommend the pads (especially since mine were free), since the difference is probably siginificant enough for most people to bother.

Oh, and out of curiosity, how long did it take you to go through it all?

All in all about 3 hours. And without any doubt - it was very hard work (and all I did was listen!).

Cheers,

Paul.

PS Congratulations on the promotion to green

Paul Haigh, 6GB, Blue
Reg: 4120 - Serial 00254
Posted by: tfabris

Re: Opinions on empeg sound stage - 05/07/2000 05:53

PS Congratulations on the promotion to green

I'm pretty sure that just means I'm one of the moderators. Not for this thread, but for the FAQ thread.

___________
Tony Fabris
Posted by: teemcbee

Re: Opinions on empeg sound stage - 05/07/2000 06:01

Now after all the posts - what do you think about this? Will the critic (positive and negative) affect something in some software releases ( except the decoder which will be changed as someone (i think Hugo) said)?
i.e. changing volume level will affect changing of the base-level?



TeeMcBee

Posted by: Verement

Re: Opinions on empeg sound stage - 05/07/2000 07:21

In reply to:

This fascinates me tremendously. I'm dying to see what Mike and Hugo have to say about this.


I'm kind of disappointed they haven't said anything.

If the new decoder produces identical output to the current one as Hugo claims, it doesn't sound like it's going to change the situation. On the other hand, maybe the new decoder is really better. Who knows? I'm still curious to know what decoder it is.

-v

Posted by: Magsy

Re: Opinions on empeg sound stage - 05/07/2000 08:49

Rite, first off i`m not a expert like some of u seem to be, nor do i own an Empeg, although i know what sounds good, and I am very very fussy.
However, after reading through this thread (very intersting btw :) I can see one huge problem.
You all seem to be comparing mp3`s made in Audiocatalyst, which without a DOUBT, is the worst sounding encoder u can get.
Its pitiful, it crops more high frequencies that the others, I`m not surprised people are finding treble lacking.

Usin an encoder such as Lame (http://www.sulaco.org/mp3/), I really can barely tell the difference between mp3 and wav (usin HQ VBR mode 1, roughly a 180kbps file)
Check out this page for proper graphs and such, highlighting Xings (ACAT`s) below par performace.
http://www.r3mix.net/

Says it all really, even if u dont belive graphs, or others results, you must be deaf if u cant hear the difference between ACAT and Lame or any Fraunhofer encoder.
I`d recommend Fraunhofer (Radium release, or Opticom Mp3 Producer Pro)@ 192kbs, or Lame set to VBR mode 1.
Give it a go, you have nothing to lose and i think you`ll be pleasantly surprised.


Posted by: altman

Re: Opinions on empeg sound stage - 05/07/2000 10:34

There's not a lot to say - the new decoder is the one from ARM, it's very efficient and small, & has the same accuracy. It'll sound identical.

The mk2 has a cleaner sound output, tantalums in the output path to ensure better stability, etc, which may well improve the audio quality though.

Hugo


Posted by: rob

Re: Opinions on empeg sound stage - 05/07/2000 11:04

Have you tried Audio Catalyst recently? It got MUCH better about a year ago.

Rob


Posted by: rob

Re: Opinions on empeg sound stage - 05/07/2000 11:07

I don't think there have been any real conclusions about the sound stage issue, which is what interested me in the first place :) I guess the only real conclusion is that low bitrate MP3 files definitely destroy the sound stage, that higher bitrate files may or may not destroy it, and that what we really need is WAV playback to prove for sure how good the empeg hardware is.

Rob


Posted by: dionysus

Re: Opinions on empeg sound stage - 05/07/2000 11:46

In reply to:


I don't think there have been any real conclusions about the sound stage issue, which is what interested me in the first place :) I guess the only real conclusion is that low bitrate MP3 files definitely destroy the sound stage, that higher bitrate files may or may not destroy it, and that what we really need is WAV playback to prove for sure how good the empeg hardware is.


Sounds about right.. It's not really fair to blame the Empeg for mp3's shortcomings..
-mark

...proud to have owned one of the first Mark I units

Posted by: Henno

Re: Opinions on empeg sound stage - 05/07/2000 13:06

. . . Audiocatalyst, which without a DOUBT, is the worst sounding encoder u can get ( . . . ) Usin an encoder such as Lame, I really can barely tell the difference between mp3 and wav

Thanks for the links, I'll study them more closely and will certainly have a go with LAME and check for myself. (I passed testing Frauenhofer as they wanted some US$250 even for trying it out ). It's funny that, although the second link you quote is really negative on AudioCatalyst, the first link recommends it as it is supposedly LAME based:

link2
Check out this page ( . . ), highlighting Xings (ACAT`s) below par performace. (http://www.r3mix.net/)


link1
Usin an encoder such as Lame (http://www.sulaco.org/mp3/), I really can barely tell the difference between mp3 and wav.

quote from this site:
Commercial software which supports or uses LAME:
. Audiograbber. Windows ripper/encoder
. CDcopy Windows ripper/encoder
. Easy CD-DA Extractor Windows ripper/encoder, includes LAME binaries.
unquote

. . confused . .



Henno
mark2 nr: 006
Posted by: dionysus

Re: Opinions on empeg sound stage - 05/07/2000 13:12

In reply to:


Thanks for the links, I'll study them more closely and will certainly have a go with LAME and check for myself. (I passed testing Frauenhofer as they wanted some US$250 even for trying it out ). It's funny that, although the second link you quote is really negative on AudioCatalyst, the first link recommends it as it is supposedly LAME based:


Audiograbber and audiocatalyst are technically different products...
-mark

...proud to have owned one of the first Mark I units

Posted by: Henno

Re: Opinions on empeg sound stage - 05/07/2000 13:15

low bitrate MP3 files definitely destroy the sound stage, that higher bitrate files may or may not destroy it, and that what we really need is WAV playback

How big a deal is it to do WAV for Emma / Mark ?
I'd love to do a comparison

Henno
mark2 nr: 006
Posted by: tfabris

Re: Opinions on empeg sound stage - 05/07/2000 14:07

Audiograbber and audiocatalyst are technically different products...

Not really, from what I can see. Basically, Audiocatalyst is the Audiograbber front end with the Xing encoder bundled and hacked permanently into the MP3 menu.

___________
Tony Fabris
Posted by: Jazzwire

Re: Opinions on empeg sound stage - 05/07/2000 15:00

If you are feeling brave, and fancy playing around in the developer image, there is some information and code on the developer site to allow you to push a raw file out of the empeg (using dd if memory serves)
I don't know if it would work on a Mk2 though, as I need to sort out my cross compiler...

So it is possible, just not from the player software at the moment... =)

Jazz
(List 112, Mk2 12 gig #40. Mk1 for sale 4 gig #30, apply within)
Posted by: Henno

Re: Opinions on empeg sound stage - 05/07/2000 15:08

If you are feeling brave, and fancy playing around in the developer image, there is some information and code on the developer site to allow you to push a raw file out of the empeg

Nah, not that I'm scared or don't fancy playing around with the developer image, but I know nothing about Linux, so I'll have to pass until someone else cracks this, or empeg provides WAV support (pre-Beta, may be?)

Henno
mark2 nr: 006
Posted by: rob

Re: Opinions on empeg sound stage - 05/07/2000 15:08

It should be fairly trivial to write a small application that simply plays a WAV file, without the rest of the player around it. I know that Kim Salo already has this working, as his GPS project plays sound samples on the empeg.

Integrating WAV into the player is a bit more involved. We need to change the architecture to accommodate multiple CODEC's, which is something that will become a lot easier when we switch to the new MP3/WMA CODEC's from ARM.

Rob


Posted by: Henno

Re: Opinions on empeg sound stage - 05/07/2000 15:18

It should be fairly trivial to write a small application that simply plays a WAV file, without the rest of the player around it

I'll ask Kim. Thanks

Henno
mark2 nr: 006
Posted by: Magsy

Re: Opinions on empeg sound stage - 05/07/2000 15:36

Ok, I have used ACAT recently, i have 2.1 on here now, its fine for ripping, just not encoding.

To answer the Xing related thing. Um, your way out :)
Audiograbber is just that, it grabs the tracks, it has an inbuilt front end for making mp3`s using external enocders, such as XING or lame, that the only relation.
It just acts as a gui for Lame.
ACAT is audiograbber, with xing built in.
I`ll get flamed for this, but if you want Opticom Mp3 Producer Pro 2, let me know..

Posted by: Henno

Re: Opinions on empeg sound stage - 05/07/2000 15:55

Audiograbber is just that, it grabs the tracks, it has an inbuilt front end for making mp3`s using external enocders, such as XING or lame, that the only relation. AudioCatalyst is audiograbber, with xing built in.

You're right. The encoder settings for AudiCatalyst (2.1) say that they are for the Xing encoder.


Henno
mark2 nr: 006
Posted by: teemcbee

Re: Opinions on empeg sound stage - 06/07/2000 00:07

Well - I didn't blame them at all! I just asked if they see anything out of this tread which should be canged. I'm pretty sure that my sound-quality-feeling will be satisfied with the Mk2.

(currently I have to listen to a tape-deck! I think everyone knows how noisy that is...)


TeeMcBee

Posted by: Amarth

Re: Opinions on empeg sound stage - 11/07/2000 00:19

I am also preparing for an Empeg mark2 and first time really got into encoding .mp3's. I have a lot of CDs (well, a couple of hundred) but ran into the problem of finding a decent mp3-encoder.

After a little work and research, I hear a lot of people were using things like MusicMatch 5.1 (www.musicmatch.com) or Xing's AudioCatalyst (www.xingtech.com) - while I have heard they were getting 'excellent reviews' from the magazines, I got really concerned whether they had covered the usual 'packaging','ease of use' etc. aspects too much.

I saw a comment about the LAME encoder (http://www.sulaco.org/mp3/) which seems to be an open source project, their webpage lists AudioGrabber (http://audiograbber.com/) as one commercial software that can use the LAME engine. I will myself give that one a try as many of my musician friends are referring AudioGrabber as a top-notch rip-utility.


Posted by: dionysus

Opinions on LAME? - 11/07/2000 07:10

Has anyone actually tried LAME? What's people's opinion's about it? I would like to include a little section in the FAQ about what PEOPLE (and not biased reviwers) think about the different encoders...
-mark

...proud to have owned one of the first Mark I units
Posted by: Kureg

Re: Opinions on LAME? - 11/07/2000 08:04

In reply to:

Has anyone actually tried LAME? What's people's opinion's about it? I would like to include a little section in the FAQ about what PEOPLE (and not biased reviwers) think about the different encoders...


Well, I followed that link posted here not too long ago. http://www.r3mix.net/

It gave some pretty staggering results. It's makes a rather strong claim that Xing AudioCatalyst chops off the high frequencies above 15khz intentionally (and may be the reason for it being so damn fast). That really concerned me, although I've never personally noticed it when listening to a song. So, I downloaded LAME. The url above indicated that LAME was the only encoder that didn't mangle the song badly.

I encoded about 10 songs at the highest quality VBR setting of both encoders (normally, I encode my songs in Xing AudioCatalyst 2.1 at the higest VBR setting).

I did several of my own unprofessional and probably inconclusive tests, but they at least helped me formulate my own opinion. The first test was simply to play the song from beginning to end using the WAV first, then the LAME mp3 second and then the Xing mp3 last (for all 10 songs). The second test was to find a spot in the song that had a lot of high frequencies, then open up three players each with a different form of the song (wav, lame mp3 and xing mp3). The section of the song (2 or 3 seconds) was played in sequence using all three players in the same order as above.

Now these tests aren't in any way highly scientific. I just did them to try and decide if it was worth re-encoding my collection all over again. The nice graphical display at r3mix.net is probably true but I wanted to know how it sounded.

The biggest difference I noticed was that LAME takes much longer to encode the song (5 minutes for the song as compared to Xing's 45 seconds).

Through all the songs and tests, I could not tell the difference between Xing and LAME encodings at the highest VBR setting. At times I thought there might have been a difference between the mp3's themselves, but they both sounded identical to the original WAV file so the effect was probably pyschological.

I think the strongest selling point I can offer to LAME is that it is FREE, and it is a high quality encoder. It is probably a higher quality encoder than AudioCatalyst 2.1 but I couldn't tell the difference myself. For anyone out there who hasn't bought a good encoder yet, a good one is available for free and I would see no reason to purchase one. Another program that makes a great companion to LAME is the EAC (ExactAudioCopy) program (http://www.exactaudiocopy.de/), which is also free (I believe the author wants a postcard for registration, but the software doesn't appear to be crippled in anyway). These two products together make almost the same thing as Xing AudioCatalyst (without the speed).

Xing AudioCatalyst 2.1 has the benefits of speed and the look and ease of a little more professionalism. I didn't notice any of the quality sufferings that r3mix.net claimed existed, but I might just be deaf! I'm quite happy with it myself. If you've already been using Xing AudioCatalyst 2.1, I don't think there is a need for you to re-encode all of your songs again.

On the other hand, my tests were only with the highest VBR setting. r3mix.net indicated that even the highest VBR setting in Xing suffers the high-freq flaw, but I sure as hell didn't notice.

These are just my opinions of what I heard. I am not arguing any technical differences between the two, and I have not compared the CBR settings of the encoders (so for all of you out there that use a constant bitrate, you may have to do your own tests). Also, I only did testing with 2.1 of Xing. Prior versions will likely produce different results.

Hope this is helpful. Consider this just a review as others will have their own opinions.

Kureg


Posted by: tfabris

Re: Opinions on LAME? - 11/07/2000 10:18

Good coverage, there, Kureg.

I'm currently re-evaluating my encoding options, and looking at Fraunhofer, LAME, and Xing (Audiocatalyst).

I spent a lot of time with two different versions of the Fraunhofer command-line encoder, and for me, they did the best job at fixed bitrates. Unfortunately, they don't do VBR, so it's into the bitbucket with them.

Now the race for me is between LAME and Xing. Both encoders have had recent improvements which significantly improve their sound quality. I have personally verified that Xing badly mangles an 18khz sine wave, so the complaints that Xing discards high frequencies sound valid. However, almost all MP3 encoders discard frequencies above 16k, with only LAME claiming to handle those high frequencies at all. Even if LAME does reproduce those high frequencies, can it possibly be doing them accurately? Maybe there's a reason the other encoders discard them.

The only thing about LAME which scares me is an admitted flaw that can be found in its own documentation:

Note: VBR is currently under heavy development. Right now it can
often result in too much compression. I would recommend using VBR
with a minimum bitrate of 112kbs. This will let LAME increase
the bitrate for difficult-to-encode frames, but prevent LAME from
being too aggressive for simple frames.

This means that I have to specify a "bitrate floor" of 112kbps in the command line. Which, although understandable, means that I'm not getting the full bang-for-the-buck out of the VBR format. In other words, why go to the trouble of doing VBR if you can't have it compress the simple frames below 112? The result is larger file sizes, and the whole point of VBR was to get smaller file sizes.

As far as encoding speed, the LAME encoder, although slower than Xing, is much faster than Fraunhofer. So I'm considering doing some long-term testing with LAME. In fact, I've just added some encoder presets to my Jack program to support LAME. We'll see how it goes.

___________
Tony Fabris
Posted by: Kureg

Re: Opinions on LAME? - 11/07/2000 13:07

In reply to:

This means that I have to specify a "bitrate floor" of 112kbps in the command line. Which, although understandable, means that I'm not getting the full bang-for-the-buck out of the VBR format. In other words, why go to the trouble of doing VBR if you can't have it compress the simple frames below 112? The result is larger file sizes, and the whole point of VBR was to get smaller file sizes.



What I've noticed on a few files is that the minimum bitrate seems to be a preferred minimum bitrate, and that there is a "force" option elsewhere. There are parts of the song that compress more than the minimum should limit, but hovers very close to that mark. This is very distinguishable in the fade-out portion of a song (at least for me ).

Kureg


Posted by: danthep

Re: Opinions on LAME? - 12/07/2000 01:22

With regards to speed, when you turn all the high quality options in lame you enable all sorts of paranoid acoustic analysis, probably much more than xing is doing. That slows it down lots.

Secondly, lame is designed for portability; it works on lots of different OSes, and lots of different CPUs. If you just want speed on the x86 platform, try GoGo. It a varient of lame targeted at top speed on the x86 platform. It has assembly optimisations, as well as MMX, 3DNow, SSE, and Athlon enhanced 3DNow optimisations. It's fast!