[halman]

I got my boards today

 

[audioengr]

Quote:

Originally Posted by Magsy Same here, I would like to build a high end usb dac! edit: woops, you say usb>spdif, I'm after usb>analog!

I am prototyping a 2706 circuit with I2S out for use with the P-3A DAC (I2S input). I would rather do a 3200-based board with both I2S and S/PDIF outs as a product though.

BTW - there is a way to isolate I2S from the PC: Differential signalling.

Steve N.

 

[BradJudy]

Quote:

Originally Posted by audioengr I am prototyping a 2706 circuit with I2S out for use with the P-3A DAC (I2S input). I would rather do a 3200-based board with both I2S and S/PDIF outs as a product though.

It will be interesting to see what comes of this. I own an AA DDE 3 which also has i2s input.

 

[steinchen]

Quote:

Originally Posted by Magsy Same here, I would like to build a high end usb dac! edit: woops, you say usb>spdif, I'm after usb>analog!

me, too

 

[Stuge]

I've made one of these. It's just the simple reference design in the PCM2902 data sheet along with a TOTX179 and TORX179 and their respective suggested operating circuits.

The motivation was to record music from laptop on my Sony MDS-JE520 MD deck bypassing the DAC and noise in the laptop. DIY because, well, I didn't want to spend 350SEK on consumer electronics in a store when I could DIY for around 250SEK. ($50 vs. $35)

Optical transmission because I like optical signalling in general. Plus my desk has lots of signals back and forth and the laptop is a noisy system, so the noise-resistant factors of optical outweigh price of electrical, plus there's the subjective argument that optical feels better. I've read some posts and articles stipulating that optical transmission actually introduces more bit errors in the data stream than electrical signalling but I haven't decided how much I believe that just yet. I guess it comes down to the quality of the components in the system; the attenuation in transmitter, cable and receiver.

At first I planned on only having an optical output but a friend of mine with a synth said he could probably use a digital input soundcard so I put a receiver on it as well.

I had some 15 boards made and have populated one so far. It sort of works. The MD deck unlocks stochastically, causing short glitches in sound, rarely more often than once a minute but sometimes it runs for hours without a glitch. Suggestions on a remedy for this are appreciated. I haven't made any thorough tests since I have other priorities at the moment. I read a post on a japanese board where a TI tech seemed to reply about how one of the DIR S/PDIF receivers had to be externally reset if the sample rate changed, but I don't believe that's what I'm seeing, and I doubt there's a TI TosLink receiver in the Sony deck, and the source applications (xmms/mplayer) don't just switch sampling rates.

Bus powered, all SMD, hand soldered. One bug in the PCB, forgot to ground the TOTX179; that's the red wire.. Just wish the deck wouldn't unlock. Need to investigate further. There's a lot going on in the ALSA USB driver right now as it seems too, my keyboard stops working if I unplug and replug the device because of bugs in the Linux kernel..

Photos: http://cdy.org/~stuge/usnd/

//P

 

[drewster]

Hi folks,

First time poster here. I found this thread while googling for information on the PCM2902 chip.

This might be out of place in a DIY thread... but a vendor sells just this kind of product - ADS Technologies. They use the 2902e, and the device has USB, RCA in/out and S/PDIF in/out. They call it the Instant Music RDX-150.
Product: http://www.adstech.com/products/RDX-...sp?pid=RDX-150
Froogle: http://froogle.google.com/froogle?q=...b=wf&scoring=p

No relationship, no affiliation, yadda yadda. I never heard of the ADS device until the other day, and saw it tonight when a friend brought one to my house. My curiousity led me googling, and here I am.

Cheers!

 

[dsavitsk]

There seem to be tons of usb cards with toslink out, but ours has wired output specifically to facilitate putting it inside an existing dac with a minimum of fuss. It is interesting to note that this one uses the 2902, however, How does the analog sound? we opted to not bother since there are better chips for it.

In case you didn't see it, the group buy thread for this is at http://www6.head-fi.org/forums/showthread.php?t=109671 and the project page is at http://www.ecp.cc/usb-spdif.html

-d

 

[needlz]

Anyone using a Mac with this board? I just finished building mine and after plugging it in the LED lights but nothing else happens. Do I need a driver or USB utility installed or is there probably something wrong with my board?

thanks.

 

[dsavitsk]

I would guess something wrong with the board. To be sure, find a win32 computer to try it in, however. The pcm2902 should be fully supported under osx.

-d

 

[Nisbeth]

You need to choose the board as your output device in the "sound" pane of your system preferences

/U.

EDIT: You can also check if the board is listed as "BB PCM2902" (or something like that) in the information for the USB-bus in your system profiler. If it is, that part of the board is working

Quote:

Originally Posted by needlz Anyone using a Mac with this board? I just finished building mine and after plugging it in the LED lights but nothing else happens. Do I need a driver or USB utility installed or is there probably something wrong with my board? thanks.

 

[paologatto]

Yep, I confirm!
The PCM2902 and PCM2906 work perfectly with Mac!

After connecting it, the new USB device will appear in the list of audio devices. No drivers needed.

And works ok also in linux.
Well.. the latest Mac OS is a sort of linux, AFAIK..

Bye!

EDIT: read an additional note about a Mac problem here:
http://www6.head-fi.org/forums/showp...&postcount=193

 

[dsavitsk]

Quote:

Originally Posted by paologatto Well.. the latest Mac OS is a sort of linux, AFAIK.

Nope, the Darwin core (what OSX is built on) is based on FreeBSD which is quite distinct from Linux. FreeBSD, however, does support USB audio (using a driver originally from OpenBSD.)

-d

 

[drewster]

Quote:

Originally Posted by dsavitsk There seem to be tons of usb cards with toslink out, but ours has wired output specifically to facilitate putting it inside an existing dac with a minimum of fuss

Ah, I missed that essential detail. My apologies.
Quote:

. It is interesting to note that this one uses the 2902, however, How does the analog sound?

I haven't wired it up to the receiver just yet. I'll update this thread when I do, however.

 

[agentpt5]

Getting ready to solder this little guy, I am asking if anyone has a link to the schematic?

 

[halman]

I finaly got around to build and house my digital output It feeds my little TDA1545 based thingy very nicely