Not the 'ultra high cable quality' thing again! Make sure you don't stand on your data cables either. I did it once and it flattened the data. Instead of '1's and '0's I got '_'s and 'i's. I then had to plug the cable into a data expander to get it all back into the right shape. The guy at the store charged me an extra $1500 for the expander box, I know it's doing its job cause it has a flashing light. If the light stops flashing, the cable has been flattened too far and I need to get the extra heavy duty cable and another data expander subsystem. I hope it doesn't, because that system costs $3500.

Keeping both bays for hard disks is critical for me. I want a digital out so I can rip DTS tracks and play them in the car, and since DTS is full CD bandwidth I am going to need all the disc space I can get.

I would prefer an external dongle approach over sacrificing the second drive bay.

Would you be willing to buy a unit with only an RCA phono coaxial output? The board can most likely be fit in the back, but the connectors are a REAL problem. I have a few toslink modules around and they are just too big to fit inside the Empeg/Rio without intruding on the drive bay. If I make the board with only an RCA jack on the back of the Empeg, it will most likely fit.

The only dongle solution I can think of is to make a small buffer circuit for the IIS signals, terminate that with a 5-pin mini-DIN in Audio Alchemy format, and then run a cable from the 5-pin mini-DIN connector to an external box containing the S/PDIF circuitry. For me, I would not want a unit that was outside the Empeg anyway. Its got to be one design only. In these small quantities, it just isn't practical to have multiple models. Each variant added would substanially increase costs.

So what does everybody want? An external unit as described above, with both coaxial and optical outs, an internal model with only coaxial output that does not intrude on the bay, or an internal model that has coaxial and optical output that does take up the bay? The external unit would have the advantage of I2S output.

Stu

I want one for two uses...

First and foremost would be to hook up to my home entertainment system.. My system only has optical connectors (but that cuz I have a Sony - I am probably in the minority here). I don't like the sound quality of the empeg's 1V outputs and this should fix it. Simply 2-channel stereo.

The second use would be so I could run a digital amp one day. This would be an expensive amp to get but it would help with noise getting in through RCA's. I also don't know how it could be dockable....

The first reason I listed would be enough for me to buy a kit/unit. The second would be enough for me to spend more, but it is not critical (in my situation.)

I'll PM you.

I have two drives taking up both drive bays so I would definitely not want to lose the extra drive. I have ZERO issue with an external box with an audio alchemy format connector. Please please! :-)

Calvin

I would be more than happy to buy at least one providing that I do NOT have to give up the second drive bay. The high end connectors would be nice as well, but I would compromise in the interest of getting the thing inside the box.

I would be more interested in having it external if it will contain the toslink. The phono jack is no good to me.. in the car

So there is my input!

I would definitely be interested in buying a unit. I really do not want to give up a drive bay at this point though. I have too many tracks on my 60gb now. For home use the coax or toslink are fine...in the car is where my problem is. I do not know of any processors that accept coaxial in car audio. I know of units that support toslink, so I would prefer toslink if it is viable. I do not mind having to make the connection external of my Empeg.
Dave

You can add me to the list of interested people for this module in any of these forms (my car stereo wants coax, and my home stereo/PC will take either). I prefer an internal solution though.... simply because then you only need one board per player, as opposed to one board per installation location with the dongle.

I didn't see any mention in this thread regarding how the interface between the player/sled will be handled. Since we are considering having an optical output on the player, I presume the assumption is that extra connectors will be added to the rear of the unit.

In the case of an internal unit, I was planning to reallocate the pins for the the mic input (or rear outputs, etc) on the docking bay connector for the coax digital output. The docking sled wire harness would be modified such that the this mic connector would be replaced with an RCA (or maybe use a mini-jack to RCA adapter cable). Anyone see any issues with this plan?

As far as the final solution, here's my suggestion:

Offer the internal kit with coax output only. Everyone gets to keep two drives. Coaxial output is the default output. This has the advantage of being able to be transmitted over the docking bay connector so that adding an extra rear jack isn't required (but optional if you don't want to sacrifice something on the docking connector). Plus I imagine the cost would be lower for the base kit since you don't have multiple ouputs, with the associated electronics and connectors, etc.

Then, have an external dongle module available that could convert the coaxial signal to optical.... in fact, these can already be purchased as retail products for home use.... the links below are for such adapters, one is $25 and the other $30. The only problem is that they are intended to run off a 6 V DC.... so something would have to be worked out to make them run off 12 V DC (or maybe they could run off the 5V from the player).... I have seen schematics for these and they seem pretty simple.... one could probably be made for even less if you wanted to make one as an option. Or perhaps a more thorough search would turn up a unit in the same price range that already runs on 12V....

http://www.soundprofessionals.com/cgi-bin/gold/category.cgi?category=580&item=SP-COAX-OPTICAL&type=store

http://www.cablesandconnectors.com/01700-01.HTM

I prefer not to have add an extra connector to the rear of the EMPEG. For one, their would be the same problem already encountered with the ethernet connector... you can either accept it as not being dockable and manually plug/unplug the cable when you install/remove the player or deal with the problems of trying to make a toslink, RCA, or mini-DIN connector dockable in the same manner others have done for the ethernet connector (although this would probably not work as well for these audio types of connectors). Either way, with the optical interface, this means that the optical cable and output jack are exposed whenever the player isn't docked.... and you have to worry about dirt, dust, etc over the long term (you could always put one of those Toslink blank covers in place when the player is out, just don't forget to remove it before throwing the player in the sled!). Lastly, I am not too excited about making any permanent mechanical modifcations to the rear chassis (drilling holes in it, etc).

I dunno, just my two cents.

As I said, I'd be interested in this in any of the variations you presented.

I like your idea about going with the adapters if optical output is needed. I was about to offer that suggestion myself. I think everyone that expressed interest in an optical output said they wouldn't mind a dongle. Well, that adapter would then be that dongle. A simple voltage regulator circuit would take care of the voltage mismatch.

I had just planned to put the connectors, whether they were optical, I2S, or coaxial at the back of the Empeg. The docking ability would of course be limited by that solution. Sending the coax digital signal through the mic input cable sounds like a great idea too. Thanks for your input.

Update: I'm just about ready to order the parts for the first prototype. Probably tomorrow night. Once they come in I'll check the fit on the PCB printout and if all goes well I'll order the PCB. In couple weeks I should have the proof of concept prototype finished. Sorry things are moving so slowly, but school keeps me pretty busy.

Stu

I think this is the best idea yet!

-Mike

Remember the empeg is limited to 2x16 bit words, 44100 times a second. I don't think the DTS digital link works like this - it uses the link as a stream at 48kHz. Don't get your hopes up.

Hugo

Running the sp-dif signal out of a mini-jack is ok with me. It seems like that mic input is never going to be used, so sacrificing as a sp-dif out works for me. I don't need optical out as my DTS decoder uses sp-dif rather than tos-link.

As for DTS, there are two kinds. The kind on DVDs is 48KHz, but the kind on DTS CDs is regular 44.1KHz (it has to be as it must play back on regular CD players). I plan on using the later.

It sounds like the coax only is the way to go. For those that use the unit at home without a dock, they will still need to install an RCA phono jack in their Empeg/Rio.

By the way, S/PDIF is a format of digital audio tranmission that can be carried over both optical (Toslink) as well as coaxial (phono,etc.). That is to say, Toslink also qualifies as an S/PDIF output. I just wanted to clear up the confusion.

Stu

Parts are on the way.

I would definitely be interested, since an outboard DAC could easily eliminate that horrendous 50dB stereo separation and 18kHz rolloff in freq resp! Either Toslink or coax would be appropriate, since most DAC's will take either, although lower-end units only have Toslink. I think $50 would be reasonable, depending on the complexity of the circuit, although I have a bad feeling it would cost more...at some point ,the sound improvement from a digital output board + DAC isn't justified by the cost (e.g. the money could be put towards better spedakers), but oh well. :-)

The circuit is not all that complex. It's got about 40 components. Still, given the extremely small quantities I would be purchasing the parts in, as well as the hand assembly, $50 would be an impractical. I would lose money on every one made. I think the most likely price would be around $100.

at some point ,the sound improvement from a digital output board + DAC isn't justified by the cost (e.g. the money could be put towards better spedakers), but oh well. :-)

Remember, the better your speakers and other equipment, the more you are going to notice any deficiencies in the Empeg's D/A converter. Many people spend much more than $100 on cables. Unlike these cables, the digital output will make a real difference in the sound, provided you are feeding it into a good quality D/A converter.

Stu

I'd love to know where you've seen an 18kHz rolloff from the empeg; it's a LOT flatter than that to beyond 20k. The home outputs had worse rolloff on early mk2s, but this was fixed on the mk2a (requires removing 2 caps). The car outputs weren't affected.

If you have bad channel separation (on an early mk2, sernrs <about 500) then you can improve this by changing one component - this was the wrong part being fitted by the manufacturer. It doesn't affect the mk2a's. Channel separation should be >~75dB on mk2as.

Hugo

I would like an external unit with a optical output. (Toslink)

Just for clarification I need a few questions answered.
1.) If you use a digital out you lose the volume control capabilites with the Empeg correct?

2.) If #1 is true, then a separate preamp would be needed?

3.) I know that Zapco and Precision Power make a D/A converter for the car, but are there any that I am missing?(Please include sound procesors that you know of as well)

Dave

You should get to keep the volume control as the signal feeding the board I am building is the same one going to the Empeg's internal D/A converter.

I can't comment on the existence of car D/A converters or sound processors.

Stu

You should get to keep the volume control as the signal feeding the board I am building is the same one going to the Empeg's internal D/A converter.

Except that the signal they feed to the internal D/A converter is full-range, and a separate command sent to the DSP itself is what controls the output volume of the DSP (as well as other things such as balance, fader, EQ settings, etc.).

So I think he's right, the output board you're making will feed raw digital bitstream to the output, and it will be up to your external digital decoder and amplifier to supply the volume control.

Please refer to the first two messages in this thread . Here Sven asks if he would still have use of the EQ if he were to add an S/PDIF board through the IIS outputs. Hugo replies yes. So it would seem that at least the EQ would be available.

I'm not real familiar with the functionality of the Phillps DSP in there, but it would seem that any change in volume, EQ, etc. would have to pass through the D/A converter in order to be audible. Since the IIS outputs are the same as those for the D/A converter, it would seem that indeed the signal feeding the board is the altered one from the DSP and not necessarily full volume, full range. Perhaps I'm missing something. Maybe Hugo could clear this up?

Stu

If so, then I'm misunderstanding the signal and data chains in the player's internal architecture.

The output stream on the I2S pins is the same thing that goes to the internal DACs. There is no post-processing for volume (etc) post DACs, everything is done digitally pre-DAC.

Hugo

Hello,

For about 100$ i would definatley one of those boards. Toslink _and_ coax would be perfect. If that is not possible i would prefer coax.

Altman: i got one of thoose affetced empegs (serns < 500). Could you tell me which component i have to change ? Thanks a lot.

Regards

janosch

Sounds like we get to keep volume control after all. Glad I was right for a change!

Stu

Back in March 2001, Car Stereo Review published a review of the Empeg MK2: http://www.m-emag.com/reviews/reviews.html?reviewID=60
Frequency response of the unit was measured at -2.4dB at 20kHz, which you might argue is not audible, but honestly is pretty lousy for a digital source. This is consistent with the Empeg spec sheet, which gives the freq resp of the aux input at 20Hz-18kHz. Maybe they measured an older unit? However, most sources sampled at 44.1kHz (like a CD) suffer from horrible quantization noise above 20kHz, and you'd need a brick wall filter to get rid of those artifacts -- I'm not sure I'd agree that freq resp would be flat past 20kHz. Most mp3-encoding methods get rid of that freq range anyway because it's not audible and it's a waste to encode. In fact, the latest r3mix method for LAME has a low-pass filter at 19.5kHz.

The channel separation was also measured by Car Stereo Review: 40.1dB at 1kHz and 38.2dB at 20kHz. I think a record player has better stereo separation -- again, pathetic specs for a digital source, and i would argue audible in a well set-up car system. This is consistent with the 50dB stereo separation published in the manufacturer's spec sheet for the aux input. I'm hoping that the poor separation is from the analog output stage....if it's from a stage before the proposed digital output (aka in the DSP equalization stage), then the outboard DAC ain't gonna do squat. I'm not sure where your 75dB value is derived from.

If there are any other lab measurements available, I'd definitely be interested!!! The slight loss in high freqs I could care less about, but 40dB stereo separation is horrendous. Thanks!!

Valsalva

Car Stereo review would have been playing mp3s and not wavs unless they went so far as to install a beta (which wasn't publically available yet). Most mp3 encoders have high frequency roll off as part of thier design. This can be defeated at higher bit rates wtih some decoders.... If Car Stereo Review created thier own mp3s, we may never know how they did that...

The only way I could see this not being the case is if they made their messurements with the AUX in and Line Level annalogue source... but this adds another AD-DA conversion correct?