I have been working on a digital output board for the Empeg for my own uses. It's coming along nicely. Would anyone be interested in purchasing one assuming I get mine working? It will have S/PDIF output through RCA and most likely toslink as well. What do you think a reasonable price would be? Given the small production level, it wouldn't be real cheap, but obviously, the more people that agree to buy one, the cheaper it would be.

Stu

Yeah. I'd probably get one. Is it a kit or you building these things yourself? If it's a kit, you selling the components as well?

Any rough idea of pricing?

- Trevor

I guess it could be either way, that is a kit or prebuilt. The prebuilt ones would all be hand assembled by myself. Some of the components are hard to find, so a kit might be of interest to some people. Either way, you're going to have to solder (yourself) a ribbon cable to the Empeg board to feed the necessary signals into the dig. out board. If there are individual components you are interested in, I suppose I could sell those too.

Depending on quantity produced, I think a kit might go for around $60-$80 US, and a completed board for a $100-$120. These might come down of coarse if there are enough preorders. First, though, I must finish the prototype. We'll see how it goes.

Stu

I would want one - 100% .

I'll buy one. Can you put in the necessary buffers and pass out a i2s output through an audio alchemy style connector? There's a lot of audiophile outboard DACs that take i2s inputs. Please please?

Calvin

Yup, definately put me down for a prebuilt one if you're doing them. If not then I'll just have to get the soldering iron out

If you're a true audiophile then you'd be wanting a special gold plated empeg to get better sound out of it...

As a side note, can anybody really hear the difference between the ends of a interconnect? Apparently the way the copper is drawn makes a differences to which way the current should flow! If so then you've definately got better ears that I have!

- Trevor

Apparently the way the copper is drawn makes a differences to which way the current should flow!

Hah, good one.

These Audio Alchemy connectors are 5-pin mini-DIN right? I'll look into it incorporating that feature, but no promises.

Stu

I thought it was a joke as well but companies actually do print Amp & Speaker and little arrows on the ends speaker cables!
This company even make special power cords... Last paragraph of the "Standard Power Cords" section explains about why it's directional...

I've got some no name cheapo speaker wire and it's fine for me. I'm playing MP3s anyway

- Trevor

Man, those are impressive. What do they charge for them? I'd love to see some double blind tests with these. If one person in their company could hear the difference i'd be impressed.

Matthew

hahaha!! That is a good one!

Directional Speaker wire? C'mon, I've never heard sooo much B.S in my life! Speakers run on ALTERNATING power. THAT means the current is continuously changing DIRECTION within the wire!
If it was run DC, then the spaeker would only go in one direction until the polarity is reversed again, which would then be creating AC again.

Go figure. Buy the cheap but soft speaker wire!

Oh, I'd also buy one for sure! But only interested if it's TOS LINK AND SPDIF!

Would pay no more than 60-70$ for the components only.

You will never see a double-blind test on something like that (at least not a proper one) because it's bullshit. Any true double-blind test would reveal that.

We have Barbers shops and magazine stands ("same as" you'll say, I'm certain) with HiFi mag's extolling the virtues and benefits of products much like 1.5m phono leads selling in the region of $1500.
Ok, they're impedance matched, colour matched, made from the latest material including/excluding (delete where applicable) some rare earth element that's either in or out of vogue at the time of manufacture.

What I can't believe is that even a single digit proportion of their readership would allocate that kind of money to such a specific part of their HiFi setup. At the same time I'd attribute an even smaller number against those who really could tell the difference anyway.

My guess is a lot of these technologogy trends are merely an attempt at built-in obscalescence under a different guise.

That's what I thought as well

Some places do say their interconnects are directional because the shield is only connected at the source end. This way it will try to keep any interference away from the amp which I can sort of see the logic. But the whole idea about it being directional because of the copper is just too bizarre for me

- Trevor

I can understand the shield thing. Although I'd only lift the shields if I were having a noise problem, I wouldn't lift them on all interconnects.

In reply to:

---

Can you put in the necessary buffers and pass out a i2s output through an audio alchemy style connector? There's a lot of audiophile outboard DACs that take i2s inputs.

---

Does anybody know the pinout on the Audio Alchemy connector? I can't find it anywhere.

Stu

Mark me down for being interested in the digital output board. I'd be interested in a pre-made board. I am primarily interested in Toslink connection, but having both would hurt. Here's hoping that the final prototype comes very soon.

George

As soon as the first protoype is completed and fully functional, I will put together a website providing specs on the board as well as ordering details.

Stu

Are you going to be releasing a board for doing it surface mount? It sounds like you already had an smt design.

-NiCKEL

The board will be centered around a Crystal CS8405A-CS transmitter IC which is surface mount. It was the only device of its kind that I could locate that was readily available. Other than that, everything else will be standard-sized componentry.

Stu

At this point do you know what the overall size of the unit will be compared to the original?

I know in my Miata there is somewhat limited space.

I got the impression that you were trying to make the unit mainly through hole. My previous post was inquiring if you would be designing a surface mount version. For those of us with a limited space this might help.

Surface mount really isn't that much worse to solder.

I'm not sure I understand your question, but I will do my best to answer it. By the "original," I assume you are refering to the original dimensions of the Empeg itself. This being the case, the overall size will be the same, as the unit will go inside the Empeg, either in the spare drive bay or along the back. There will not be two versions of the board. At present, the board is 3.8 inches by 2.5 inches, but I will most likely increase the density and decrease the size after I know the circuit works as intended. I think with mostly conventional through hole components, I can still achieve more than enough density to fit it inside the Empeg. I still need to measure inside the Empeg to be sure things will fit though.

Stu

OMG I must be on crack

Sorry for the confusion, I havn't slept much in a long, long time and apparently I have become easilly confused

I, for god knows what reason, got this confused with the external tuner module. Obviously it is an entirly different beast.

People pay good money for CD demagnetizers too. I can't imagine what good such a device would do for optically read nonmagetic media.

What? You mean my green felt tip marker pen doesn't do anything when I put it around the edges?!?

- Trevor

Green marker... geez, I haven't heard that one in a long time!

I love how some companies can charge top dollar for Toslink cables. "Your zeros will be more round, more natural sounding... your ones will be crisper - giving you the detail you demand. You know, I bought a printer cable for my um... printer and it has gold connections on it. It is the "premium" cable. You should see the results! My word documents have that depth that can't be obtained by standard printer cables.... I'm glad I didn't waste that money on better paper.

Why don't companies own up and admit that the only good that gold does is reduce corrosion?

If you make them and sell them, and they will fit inside an empeg that already has two hard drives...then I will definitely buy it from you... 100%

That may or may not be possible. It would have to go in the back of the unit and it's very tight back there. Maybe with SMDs it would work. It just isn't possible to put all the features everyone wants into the board. We'll see. It depends how adventurous I feel.

Stu

I'm hip to that, as well, I'd hate to have to gve up a drive bay.
Not sure that I would, infact.

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?

Go re-read Hugo's post!

He specifically stated that the Rio (Mk.2A) player has these problems fixed. CSR, as you pointed out, reviewed the empeg (Mk.2) version. We were so shocked to see the figures in that review that we went back to the manufacturer and discovered some production problems (that were not present in the original design). Hugo described these in his post.

Rob

CSR's technical guy in Florida tooks his measurements using (as I recall) reasonably high bitrate MP3 files. There wasn't any straight forward way to play WAV files at that time, and in any case they made the point to me that they were testing a whole product - which was specifically intended for MP3 playback. That's reasonable.

Rob

OK, Hugo...

If you're going to be popping off about the MK2's need part replaced for home outs then I need to know which it is (sn 080000404), also which caps need removal to change that roll-off?

Thanks in advance for the info... :-)
Tim

I have measured the frequency response of my MKIIa and see some rolloff at both ends of the spectrum. It's not too bad when playing a WAV off the EMPEG, but is a bit more significant when playing a test source through the EMPEG (via the aux-ins).

The attachments to this message (and the next two replies) show the frequency response I measured on my primary MKIIa a few weeks ago when I was setting up my PC based RTA. These graphs already have a compensation curve factored in that compensates for my sound card's response anomalies.

The RTA resolution is set at 1/12 oct in all these images.... Curve smoothing is not enabled, which is why you see steps in the response curve on 1/12 octave boundries.

The image attached to this message shows the frequency response measured at the EMPEG's 1V outputs while playing a pink noise WAV ripped directly from directly the 2001 IASCA test disc.

The response is pretty good, but other audio equipment I have tested is generally flatter.

I tried various output levels (-10 dB to 0 dB), the 1V outputs, the 4V outputs... all yielded pretty much the same results.

Looping my sound card output back into it's line input results in a nearly ruler flat measured response with the same compensation curve (see second reply to this message). Playing this pink noise track on a good home audio CD player also yields a flat response curve. Therefore, I am confident in my test setup, and that these graphs shows the actual response of my EMPEG.

And this attachment shows the frequency response through the aux inputs. Basically, the PC's audio output is fed to the EMPEG's aux inputs. And then the EMPEG's outputs are fed back into the soundcard.

For reference I replaced the EMPEG in this test chain with a set RCA barrel connectors, without changing anything else in the test setup (so that the input and output patch cables were still in the loop). With the EMPEG barreled out of the chain, the response was flat from 20Hz to 20kHz. The measured response of this test is in the next reply.

And lastly, this attachment is a test of my measurement system. This is with the PC sound card's output externally looped to the line input of the same card. Basically, I just disconnected the RCA patchcords from the EMPEG, and put RCA barrels in it's place (so that the input and output patchcords are still in the test path).

This also shows that the slight level offset between the left and right channels in the previous graphs is partially due to my sound card.

Yes, and it was this review which caused us to go "hang on a minute! the original production units were much better than that"! We did contact them about this, ISTR we were going to send them a later unit and they were going to re-do the audio tests. Actually, we were a little annoyed that they didn't ask us if we were aware of this issue before publishing the figures, because 40dB is pathetic and does indicate a design/manufacture problem.

ISTR we were down something like -0.5dB to -1dB at 20kHz on later mk2s and all mk2a's.

The stereo separation problem was due to a 100 ohm being stuffed in the car output circuit instead of 0 ohm - again, this was fixed on the production line & any units that came back to us had it done as a FCO. This, as you say, is a biggie - it's NOTHING to do with the aux input specs (which *does* have left/right interactions as the high-CMRR front end takes a ground input common to L/R to reference both from - it's likely that there will be some crosstalk introduced here).

Hugo

I seem to recall that we did get the results before they printed them. I supplied a great deal of feedback to their copy and they integrated some of that into the review. They chose to print the test results even though I refuted them.

The moral of the story is to always check review units thoroughly before sending them out, because you don't get a second chance (a lesson taught to Rio by the WSJ recently).

Rob

Any updates on the progress of the project? I have an oppurtunity to purchase a very good D/A converter for Car Audio use but, it is not cheap...even though it is used. Just looking for a little head's up on this.
Dave

Talking about volume control:
Controlling the volume on the digital path is quite a non-sense operation.
This will reduce the digital resolution down from the original 16 bits. This means reduce the Dynamic and increase the background noise.
The digital output of the SoundBlaster works in this way... when i use it, i have to set the PC volume to the maximum before clipping and set the volume of the ampli to get the proper volume level.

The only way to avoid this problem on the EMPEG , is to use a ANALOG volume controller connected after the external DAC... it could be a active or a passive preamp.

I hope, anyway, that the digital output will be a fix-volume one… just after the CPU, like any CD player has.

P.S.
I do not think the EMPEG sets the volume on the digital path ... There is probably some where ... in the analog path of the signal, a gain controller. It could be inside the dac.

Ok, the update. Well, I have all the parts I need to build my first prototype with the exception of the PCB, which I ordered last night. This should be in by Friday. So, I should be able to build and test the circuit this weekend. This protoype is not surface mount, that will be a few more weeks. If you can't wait, I may be able to get a couple out in the next two weeks, but these will take up the second drive bay. The surface mount version will fix this problem. Before I go to work developing that however, I have to work out any bugs in the original design.

Either way, these will have a coax S/PDIF output and that's it. You can't please everyone.

Stu

Great work. Definately getting one if you can get all the bugs sorted. Any ideas on pricing yet?

Now what would be neat would be digital in...

- Trevor

No, it does volume control digitally - lower volumes *will* loose resolution. It does dithering, etc, internally. This, as you say, is very common in highly integrated digital audio solutions. There is a curve on the SAA7705H specsheet which shows the THD+N curve vs volume setting (page 15 on mine).

Note also that the DACs are 18-bit (and the internal path is 18 bits wide), which gives us 2 bits of attenuation (6dB) without any loss of resolution. You'd be looking at a very low noise external attenuator (eg, LM1972 as used in the Rio Receiver) with good PCB layout to give an analogue volume control with less ill effects than the existing digital one.

Some DACs, eg the PCM1716 in the Rio Central/Rio Receiver, are 24 bit, allowing 8 bits of attenuation without loss of resolution on a 16-bit signal.

Hugo

Regarding pricing, I had said earlier that it would probably be $100 US. This is still a reasonable figure depending on actual interest. Kits would run $65 or so. The more PCBs I make at once, the cheaper it's going to be. Same can be said for the other parts, but not to the same extent.

Stu

Once I get the board built, it's going to need 5 volts to power it. You say that's available on the Empeg board and indeed I did see a couple headers labeled 5v with jumpers installed in them. Do these jumpers carry 5 volts from one section of the board to another? Could I get the 5 volts by installing a Molex type connector on one of these headers? What size are they? Thanks.

Stu

The first board has been assembled. I'm going to be brave and hook this sucker up to my RioCar later today, after I get some sleep. Still to be done is to find a good source of +5 volts and the proper settings on the chip. Luckily this version of the board has jumpers. I'm not quite sure how to handle the reset pin on the chip. I left it floating. Hopefully it will work that way. I couldn't tell from the documentation whether it was necessary or not. I'll post the results when they are in.

Wish me luck.

Stu

Everyone of us wishes you all the luck in the world!

Dalsemi/Maxim make some uP reset chips which might do the job if you do need a proper reset on power up. I've used the EconoReset series and they work quite nicely.

- Trevor

Yep, the empeg itself uses a MAX809T

Hugo

Update on the SMT board:
The design of the PCB is done and is now roughly 2.75" (6.99 cm) x 1.09" (2.78 cm) and that's where its going to stay. This is down from the original board's dimensions of 3.81" x 2.50" or a 68% reduction in footprint, even with additional circuitry. The parts are on order. I'll check for fit and order up the minimum quantity of PCBs.

Stu

I have decided to make the board capable of outputting coax, Toslink, and I2S. The basic model will come equipped with coax only at a price of around $100. Other models will include an additional connector and cable for Toslink, I2S, or both. So the maxed out version will offer all three formats on one board at a price of somewhere around $135. The Toslink/coax board will be priced around $130 and is only going to work on Rios/Empegs with one drive bay though, as the Toslink connector is too deep to allow for the 2nd drive, but the option is there. I2S is untested, so I make no guarantees as to whether this will work or not. The I2S/Coax board will be around $110. The coax will be via RCA phono jack. It is probably possible to route the signal out of the mic in cable for docking purposes if need be, but I haven't explored this option yet. I'll let the end user decide how to handle that.

Parts should be here the first part of this week, so I should have the PCB by Friday.

Stu

Sounds good.

For those interested. We finally got the digital connectors and board permanently installed. Here is a pic of the rear of the player.

Stu

Here is a pic of the other side of the rear panel with everything stuffed in there. It's a very tight fit, but at least it fits.

Stu

Nice work!

Hmmm, just how necessary are the connectors? Are they needed to get everything in place or could one solder the wires directly to the board or a row of pins or something like that? That'd, as far as I can see, give the disk plate a bit more room to move...

/Michael

Thanks. Believe it or not, there really isn't any interference with the drive or sled movement, but yes, the wires could be soldered directly to the board. In fact, that's what we had to do for the optical wires to fit.

Stu

Hmm, really impressive.

TommyE

vfd's bet outside of tables. microphones, states, and wolves 10 miles from mice poopoo by insects. feet or tables give up.

For anyone curious, the first edition of the install manual for the board is online. Creating It was quite an arduous task. We hope you find it useful. Get it at www.eutronix.com/media/dig-cxxxx_manual.pdf . The photos within are very large and as a result its a hefty download at around 5.5 MB.

Stu

Update:
The shipment of optical modules has arrived. All that remains is the PCB, which we expect to have in another 10 days.

To those of you who have downloaded the manual, what kind of download speeds are you getting? I'm just curious, because there really isn't any way to change it anyway.

Thanks,

Stu

Trying both IE6, and Flashget download manager I got around 30KB/Sec on my 1MBit SDSL line. Not too bad I think.

TommyE

One comment; you're taking power from the 5v *analogue* supply. This is there to supply the analogue side of various chips and is not intended to drive digital circuitry - you may be inducing some noise into the analogue outputs from your digital board (though it will probably only be slight).

I suggest the other 5v jumpers (dual jumper pair) near the PSU inductors, which is the digital 5v supply.

Hugo

Thanks! 30 KB/sec? Yeah that's not too bad, although our line is capable of more than that by quite a bit.

Stu

Thanks for the suggestion. I wondered about that. I wish they were labeled as such on the board. I've been using my Empeg for over a month now with the board inside, and haven't heard ANY noise on the analog outputs of Empeg, so whatever it is adding must be slight. Connecting to the analog CD inputs on my home stereo and turning the volume up all the way while the player is paused, I don't hear any digital noise. The analog outputs work as well as they ever did. Regardless, I will try to relocate the power source. They use a different size jumper than the analog supply jumper, so I will have to resolder a different jumper to the supply wire.

Stu

Does the Empeg have a separate digital ground I should be using?

Thanks,

Stu

The ground on the I2S pins is the digital ground. The analogue groundplane can be seen if you hold the main board up to the light - basically, from the DSP to half-way through the 4231 to the leftmost 10-way internal connector (for the docking sled) is analogue territory. Any GND you get from there is analogue ground.

Both are linked (obviously) but the idea is that it's fairly self-contained, ie no high-current digital loads draw from that plane which keeps it quiet.

Hugo

Well, the final production PCBs are in. I managed to assemble one tonight. It looks rather nice I think. It worked on the first try . Anyway, I will be contacting the people in our database to take official orders. Here is what they look like.



Stu

Well, the final production PCBs are in. I managed to assemble one tonight.

Well, I am definitely going to get a coax-only for home use. I read your manual. Looks great. I have, like, two questions/thoughts....

The board is attached with double-sided tape. I wonder how this will fare over several years in the oft-warm Empeg environment? It looks like there could be room to add 2 small (homebrew?) nylon retaining clips to hold the edges of the board. Thoughts?

The idea of using the "Mic" line as-is to route the coax output sounds appealing. Reduce the Dremel factor. Any issue with the distance that signal travels over an unshielded pair to make the connection to the Mic output? How long before the 0s turn square and the 1s get short?

Soldering wimp that I am, I will probably take this to a local electronics shop for the attachment of the interface cable...

In reply to:

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The board is attached with double-sided tape. I wonder how this will fare over several years in the oft-warm Empeg environment? It looks like there could be room to add 2 small (homebrew?) nylon retaining clips to hold the edges of the board. Thoughts?

---

I think the tape should hold up. We have had some double sided tape in place outdoors for 7 years in the hot, humid New Orleans weather and it is still holding just fine. There may be room for clips, but I don't know where they would be secured to the Empeg. Anyone purchasing the boards is welcome to install anyway they want. The manual only showcases how we do it.

As for the signal routing, we run a 6 inch unshielded pair to the RCA jack. It works fine and drives a 12 foot (shielded) digital cable very well. My guess is that it will take more like 7-8 inches to reach the connector in the opposite corner, but I don't anticipate this being a problem. Due to the extremely cramped quarters in the back of the Empeg, there really is no choice but to use unshielded cabling.

For those of you waiting, we appologize for the extended wait. We are assembling them now. At roughly 45 minutes each, it will be a while.

Stu

Even minature coax like RG174? That's quite small but it is a pain to solder properly.

- Trevor

Aside from RG174 being 50 ohms, it is fundamentally impossible to supply an installable RCA harness with shielded cable of any kind. The two conductors would prevent the two halves, center and shell, from separating as is necessary to get the connector installed in the back of the Empeg. By using two entirely separate conductors, it is easy to disassemble the harness. With an RG174 based harness, one would first have half of to unsolder the cable from the RCA jack or would have to receive an unassembled assembly from the start. I suspect either avenue would displease a few folks.

Stu

For any in doubt, here is a pic of the first batch of boards during testing. Four of these are no longer for sale.

Stu

Erm. RG176 then
I see your point about it being a pain to assemble though. It's such a short length anyway that using unshielded cable isn't going to matter very much if at all. Just ignore my ramblings

- Trevor

I plan to buy a module, but I am only really interested in the optical output. I plan to use the optical connection both in my car and in my home. Therefore, I would like to have the connection dockable.

I have never used Toslink cables before; does anyone think that it could be reliably docked like people have done with their Ethernet cables?

I wouldn't mind giving up some connections on the docking port in order to route the wires to the optical connector through the docking port. Could I run wires from the output board to the docking connector and then attach some short wires to the port on the docking sled and connect them to the optical transmitter? That way, I could just buy an extra transmitter and attach one to the car sled and one to the home sled, and I wouldn't have to disconnect/reconnect the optical cables. Is this feasible?

So, as I understand your post, you would like to run the TTL signals coming from the IC chip on the digital out board through the docking connectors on the back of the Empeg and sled. Novel approach! It even sounds like it would work. The current design has these three signals feeding into the optical module- digital ground, +5 volts, and signal. So,it would require that you give up three signal paths on the docking connector. Since the mic in line is unused, you would only need to snag one more line from somewhere else.

The other approach, docking ala ethernet, should also work. If you get the alignment right on your sled, there shouldn't be any problem. Dust is unlikely to be a problem. The current modules have a shutter, that should wipe off dust as the connector is inserted. I think that you would need to remove the locking tabs on your cable so that the Empeg could be easily removed from the sled following insertion. See my other thoughts here.

Stu

Since the mic in line is unused, you would only need to snag one more line from somewhere else.

Couldn't the serial connector on the wire loom be removed for this purpose? Wouldn't that provide enough free pins ?
I wouldn't want to give up the mic connector. Who knows, someday VR might become a possibility still (I'm still hoping), and I would hate it if I lost that possibility then just because I disconnected the mic connector at one time.
The serial connector however, from that one I'm SURE I'll never use it in the car anyway.

Or, if using the serial cable pins and MIC pins are not an option - I remember someone on this board was taking orders for additional sled plugs. It might be overkill - but you could install a 2nd sled connector in the empeg, and modify the plug in the sled.

I wonder if you can get smaller plugs that work in the same manner as the existing sled plug, but have less pins.

I too was thinking of sacrificing the 2 mic pins for my digital out in the car.

So what amplifiers for the car are available with TOSLINK or otherwise digital inputs?

Greg

I was looking at the Alpine PXA-H510 - it is a processor that accepts optical inputs. It produces the analog signal which is carried a very short distance to the amp.

This processor is best suited for dvd/video installations, and since I had no future plans for putting a screen/DVD in my car, I decided against it.

I've not ever seen or looked for an amp that will do the D/A conversion but there are tons of processors that you can get that do.

I still want the sound card though - my receiver at home accepts both coax and optical digital inputs - and I plan to build a home component sled for my empeg at some point.

EDIT: I meant to refer to my home install rather than my car in my previous post... oh well...

I read earlier in this thread that installing the optical connector inside the empeg prevents the installation of a second hard drive. Is this still the case with the final version of the design?

If so, I will plan to route the signal through the docking port.

and I would hate it if I lost that possibility then just because I disconnected the mic connector at one time.
The serial connector however, from that one I'm SURE I'll never use it in the car anyway.

But you'd have to reterminate those serial wires inside the Empeg as well, wouldn't you? ....If that were the case then you wouldn't have serial capability *anywhere*, true? Or are you saying you would steal some of the wires that share the serial connector?

I debated this myself. Ultimately I decided that VR and the uncertain prospect thereof wasn't important enough to me, so I will use those two wires for coax digital.

No, I was actually talking about removing the serial connector alltogether. But if a serial connector doesn't use all it's pins and it would be possible to use two free pins of that one, I would consider that an option too.
As you may have noticed I don't know anything about electronics. So what I'm suggesting might not be feasible at all.

But I don't see why removing the pins from the docking connector would require me to terminate them ? If the player is in "home mode" and a serial cable is connected to the player, then those pins in the docking connector are also not terminated (I think), and it still works. Or am I completely wrong here?

But I don't see why removing the pins from the docking connector would require me to terminate them ? If the player is in "home mode" and a serial cable is connected to the player, then those pins in the docking connector are also not terminated (I think), and it still works. Or am I completely wrong here?

Fear not, for I perceive that it is I, Jim, who is suffering from the dreaded brain fart!

Yes, no reason why you couldn't preserve the serial connection on the back of the unit. I was just in a mental muddle.

I thought about subverting the serial connector pins for digital output but then decided for some reason that I still want permanent serial connector on home docking station and a connector for GPS whil in car...

In reply to:

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I read earlier in this thread that installing the optical connector inside the empeg prevents the installation of a second hard drive. Is this still the case with the final version of the design?

---

No that was only a problem with trying to fit a PCB mount optical module in there. The panel mount version leaves plenty of room.

Stu

Anyone interested in a mobile DAC? I am considering making one. I have an idea of what I want to do with it. It would be very high quality with jitter reduction circuitry, upsampling, and oversampling and would be 24 bit 192 kHz internally and 24 bit 96 kHz externally. It would also have optical, coaxial, and possibly I2S inputs and a 4/8 volt output. This is a ways off, but after I finish up on the sub out board, I will be pursuing this for my own use if nothing else.

I'd be interested. How much do you think it would cost? At some point hopefully I will find a job to pay for it :-D

Calvin

Count me in on the DAC

Is this something that I should change on my my MK2 that I bought about a year and a half ago??

" The stereo separation problem was due to a 100 ohm being stuffed in the car output circuit instead of 0 ohm - again, this was fixed on the production line & any units that came back to us had it done as a FCO. "

Is there a public posting of service updates that may be needed on older units. I had to install the cap so that my dimmer will work correctly...

I'd be curious to know this one as well. Perhaps something for David to make another video of.

I have installed this module in my player and it works great, I don't see any problems with a second hard drive...

I just have one comment for people who are doing this themselves (it is realllllllllly worth paying to have it done). If you think this is a "soldering project", think again. It takes about 7 minutes to actually solder the wiring inside your player. It takes about 2 and a half hours to cut the case and install the connectors (My dad helped me and he does this kind of thing for a living).

I see that eutronix is offering installation of the product for $99.99 or $124.99. If you don't have a dremel tool and a square file, or don't have patience, make sure you let them install it.

I think it is a great product and I love it, but if you are not capable of drilling and filing and cleaning out your housing once you have drilled and filed it ( i used a painbrush and an air comperssor), DONT INSTALL THIS YOURSELF. It is hard to do.

I am curious about the sound quality from the board. Could you please answer a couple questions?

Which connection are you using (optical or coax)?

What type of component with D/A are you connecting to?

Is the sound quality noticably better with the digital connection?

Which ground did you use? The digital ground at the I2S pads or the case ground from one of the screws?

Stu

I can't really say, but probably somewhere between $400-600. I'm not sure how practical that figure is, but I will try. I forgot to mention that it will also feature dual DACs, top-of-the-line opamps, and precision voltage regulators.

Stu

I'm not sure you really want me to anwer your questions, but I will anyway

Which connection are you using (optical or coax)?
I use the coax.

What type of component with D/A are you connecting to?
I connect to a studio ADDA converter.

Is the sound quality noticably better with the digital connection?
In my case yes, but I don't think it's night and day for the average person that's content to listen to music over $200 minisystem. It really depends on the equipment you connect it to. I'm sure there are DACs out there that sound WORSE than the hardware in the Empeg. Connecting to such equipment would only worsen the sound. Also, the better the DAC, the more you will notice any compression artifacts.

Stu

If you are building this as a car audio DAC, then it should have four outputs (front left, front right, rear left, rear right) and a sub output. I think Doug would have some input here as to what features would be desirable in a high end car audio DAC. I would suspect multiple digital inputs, say, from a CD player for competition use. Perhaps a "tape monitor" style looped digital-in-out-in that allows for third party EQ's, DSPs, and so on.

Calvin

I am hooking it up optically to my JVC 500 watt reciever and listening to it in standard stereo mode (just the two front speakers). It sounds a HELL OF A LOT BETTER than it did with the RCA jacks (no more 60 cycle humm). I can't really compare to how it sounds in my truck because its an entirely different sound system. I also tried out the coax output and it sounds the same to me as the optical, both are excellent. I don't have a way to check the third connector it has.

I hooked the brown wire to the board screw like it said in the manual. I also think I hooked it up to the "wrong +5V jumper" I hooked it up to the red jumper instead of the blue jumper in the rear because I went by the picture....

It seems to work fine though...

This made me think of a question. With your upcoming Sub-out board, That is an analog signal correct? Or will we be able to run it through the digital output as well? If that makes any sense.....

The sub out board is just a very small digital to analog converter. So yes it outputs in analog only. The current digital output cards can buffer the sub signal in I2S digital format already. If you wanted a digital sub as well as full-range digital out, then just buy two boards with a special adapter cable we could make up for you. The first would be have to have I2S capability, and the second would not, but would have to be external and attached to the back of the Empeg or possibly through spare docking connectors.

Stu

In reply to:

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If you are building this as a car audio DAC, then it should have four outputs (front left, front right, rear left, rear right) and a sub output. I think Doug would have some input here as to what features would be desirable in a high end car audio DAC. I would suspect multiple digital inputs, say, from a CD player for competition use. Perhaps a "tape monitor" style looped digital-in-out-in that allows for third party EQ's, DSPs, and so on.

---

After looking into this a little more, it seems that it may be more expensive than I thought. For quantities of 1500, the distributors of the upsampler chip are marking it up 60% over the manufacturer's suggested retail price (in 100 unit quantities).

Regarding the outputs, I don't think this converter should have all those outputs or a sub out which would require a crossover. Front and rear outputs are duplicates anyway. It is best to let this device focus on one thing rather than trying to make it do everything. It would be better to let crossover function be handled by an external device, which many people already have anyway. As for the digital tape monitor; that sounds doable and like a good idea.

Stu

Good as the anaolgue outputs may be, I'm sure that going digital will make a siginificant improvement. Couple of questions (sorry if these were asked before, I did try to read through the entire thread...)

Am I right in assuming that equaliser output is available through S/PDIF (as it's in digital domain?). If so, that would be really cool!

Although acadamic, just curious: When going to next track, does the S/PDIF signal contain track markers?

More important, when in-between tracks or just in stop mode, does digital signal remain present, as my D/A can produce some clicks and pops when locking on or off from a signal?

Thanks,

Cas.

In reply to:

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Good as the anaolgue outputs may be, I'm sure that going digital will make a siginificant improvement. Couple of questions (sorry if these were asked before, I did try to read through the entire thread...)

Am I right in assuming that equaliser output is available through S/PDIF (as it's in digital domain?). If so, that would be really cool!

Although acadamic, just curious: When going to next track, does the S/PDIF signal contain track markers?

More important, when in-between tracks or just in stop mode, does digital signal remain present, as my D/A can produce some clicks and pops when locking on or off from a signal?

---

Yes, the equalizer functions the same through the digital out as it does through the analog.

There is no next track signal present, unfortunately. As far as I know, it is not available from the Empeg hardware, and so is not passed through the board.

As long as the player is powered up, the board outputs a valid S/PDIF signal.

Stu

Sorry to dig up an old thread, but just a quick question for maczrool. would it be possible to create or even adapt a digital output board for a tivo. the answer may be as easy as no, but i had to ask

It may be possible, depending on how integrated the Tivo's DAC is to the rest of the circuitry. If it has a separate DAC chip from its decoding chips, etc., then it probably is possible. Depending on the format going to the DAC, it may even work with the stock boards. We did however try to use the boards with a Rio Receiver and never were able to get it to work right. We never were able to get to the bottom as to why they didn't work properly in that application.

Stu