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#9998 - 27/06/2000 15:34 Opinions on empeg sound stage
rob
carpal tunnel

Registered: 21/05/1999
Posts: 5320
Loc: Cambridge UK
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



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#9999 - 27/06/2000 15:58 Re: Opinions on empeg sound stage [Re: rob]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31164
Loc: Seattle, WA
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
_________________________
Tony Fabris

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#10000 - 27/06/2000 16:02 Re: Opinions on empeg sound stage [Re: rob]
dionysus
veteran

Registered: 16/06/1999
Posts: 1222
Loc: San Francisco, CA
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
_________________________
http://mvgals.net - clublife, revisited.

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#10001 - 27/06/2000 16:07 Re: Opinions on empeg sound stage [Re: rob]
TommyE
enthusiast

Registered: 08/06/1999
Posts: 356
Loc: NORWAY
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


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#10002 - 27/06/2000 16:19 Re: Opinions on empeg sound stage [Re: TommyE]
dionysus
veteran

Registered: 16/06/1999
Posts: 1222
Loc: San Francisco, CA
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

_________________________
http://mvgals.net - clublife, revisited.

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#10003 - 27/06/2000 16:25 Re: Opinions on empeg sound stage [Re: dionysus]
TommyE
enthusiast

Registered: 08/06/1999
Posts: 356
Loc: NORWAY
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



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#10004 - 27/06/2000 16:45 Re: Opinions on empeg sound stage [Re: TommyE]
rob
carpal tunnel

Registered: 21/05/1999
Posts: 5320
Loc: Cambridge UK
> 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



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#10005 - 27/06/2000 16:47 Re: Opinions on empeg sound stage [Re: rob]
TommyE
enthusiast

Registered: 08/06/1999
Posts: 356
Loc: NORWAY
You know how to tempt a guy........ Eeehh...
I mean about me getting another Empeg.

TommyE


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#10006 - 27/06/2000 16:56 Re: Opinions on empeg sound stage [Re: dionysus]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31164
Loc: Seattle, WA
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
_________________________
Tony Fabris

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#10007 - 27/06/2000 17:09 Re: Opinions on empeg sound stage [Re: tfabris]
dionysus
veteran

Registered: 16/06/1999
Posts: 1222
Loc: San Francisco, CA
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
_________________________
http://mvgals.net - clublife, revisited.

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#10008 - 27/06/2000 17:20 Re: Opinions on empeg sound stage [Re: dionysus]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31164
Loc: Seattle, WA
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
_________________________
Tony Fabris

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#10009 - 27/06/2000 17:36 Re: Opinions on empeg sound stage [Re: tfabris]
dionysus
veteran

Registered: 16/06/1999
Posts: 1222
Loc: San Francisco, CA
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

_________________________
http://mvgals.net - clublife, revisited.

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#10010 - 27/06/2000 18:43 Re: Opinions on empeg sound stage [Re: tfabris]
tanstaafl.
carpal tunnel

Registered: 08/07/1999
Posts: 5377
Loc: Ajijic, Mexico
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"
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"There Ain't No Such Thing As A Free Lunch"

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#10011 - 27/06/2000 22:18 Re: Opinions on empeg sound stage [Re: dionysus]
Verement
journeyman

Registered: 02/09/1999
Posts: 97
Loc: Boston, MA, US
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


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#10012 - 27/06/2000 22:45 Re: Opinions on empeg sound stage [Re: Verement]
xavyer
member

Registered: 19/12/1999
Posts: 117
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.)


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#10013 - 27/06/2000 23:40 Re: Opinions on empeg sound stage [Re: rob]
teemcbee
addict

Registered: 04/02/2000
Posts: 687
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

_________________________
TeeMcBee
[orange]Mk2, # 080000143, 40+30 GB, Tuner, Peugeot stalk hookup</font color=orange>

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#10014 - 28/06/2000 00:03 Re: Opinions on empeg sound stage [Re: tfabris]
Henno
addict

Registered: 15/07/1999
Posts: 568
Loc: Meije, Netherlands
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
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Henno mk2 [orange]6 [/orange]nr 6

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#10015 - 28/06/2000 00:35 Re: Opinions on empeg sound stage [Re: Verement]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31164
Loc: Seattle, WA
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
_________________________
Tony Fabris

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#10016 - 28/06/2000 00:44 Re: Opinions on empeg sound stage [Re: Henno]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31164
Loc: Seattle, WA
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
_________________________
Tony Fabris

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#10017 - 28/06/2000 01:26 Re: Opinions on empeg sound stage [Re: tfabris]
PaulWay
addict

Registered: 03/08/1999
Posts: 451
Loc: Canberra, Australia
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.

_________________________
Owner of Mark I empeg 00061, now better than ever - (Thanks, Rod!) - and Karma 3930000004550

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#10018 - 28/06/2000 02:37 Re: Opinions on empeg sound stage [Re: teemcbee]
schofiel
carpal tunnel

Registered: 25/06/1999
Posts: 2992
Loc: Wareham, Dorset, UK
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...
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One of the few remaining Mk1 owners... #00015

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#10019 - 28/06/2000 02:52 Re: Opinions on empeg sound stage [Re: schofiel]
teemcbee
addict

Registered: 04/02/2000
Posts: 687
Tony has explained somewhere in this thread what exactly sound stage is.

TeeMcBee

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TeeMcBee
[orange]Mk2, # 080000143, 40+30 GB, Tuner, Peugeot stalk hookup</font color=orange>

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#10020 - 28/06/2000 03:33 Re: Opinions on empeg sound stage [Re: PaulWay]
schofiel
carpal tunnel

Registered: 25/06/1999
Posts: 2992
Loc: Wareham, Dorset, UK
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...
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One of the few remaining Mk1 owners... #00015

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#10021 - 28/06/2000 07:15 Re: Opinions on empeg sound stage [Re: schofiel]
altman
carpal tunnel

Registered: 19/05/1999
Posts: 3452
Loc: Palo Alto, CA
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



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#10022 - 28/06/2000 07:20 Re: Opinions on empeg sound stage [Re: Verement]
altman
carpal tunnel

Registered: 19/05/1999
Posts: 3452
Loc: Palo Alto, CA
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



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#10023 - 28/06/2000 07:32 Re: Opinions on empeg sound stage [Re: altman]
teemcbee
addict

Registered: 04/02/2000
Posts: 687
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

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TeeMcBee
[orange]Mk2, # 080000143, 40+30 GB, Tuner, Peugeot stalk hookup</font color=orange>

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#10024 - 28/06/2000 07:55 Re: Opinions on empeg sound stage [Re: teemcbee]
Jazzwire
addict

Registered: 09/06/1999
Posts: 483
Loc: Guernsey
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)
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Jazz (List 112, Mk2 42 gig #40. Mk1 4 gig #30. Mk3 1.6 16v)

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#10025 - 28/06/2000 08:02 Re: Opinions on empeg sound stage [Re: Jazzwire]
rob
carpal tunnel

Registered: 21/05/1999
Posts: 5320
Loc: Cambridge UK
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



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#10026 - 28/06/2000 08:17 Re: Opinions on empeg sound stage [Re: tfabris]
Henno
addict

Registered: 15/07/1999
Posts: 568
Loc: Meije, Netherlands
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
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Henno mk2 [orange]6 [/orange]nr 6

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#10027 - 28/06/2000 08:29 Re: Opinions on empeg sound stage [Re: rob]
Jazzwire
addict

Registered: 09/06/1999
Posts: 483
Loc: Guernsey
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)
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Jazz (List 112, Mk2 42 gig #40. Mk1 4 gig #30. Mk3 1.6 16v)

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