ODAC - general and technical discussions

[mcandmar]

Anybody know what kind of DC offset you should see on the ODAC output?

I measured 1.6mv & -.4mv @idle, and 8.3mv & 10.2mv dc while playing a silent track. They seem a little uneven to me?

[quaeritate]

Originally Posted by runeks

I just received my ODAC in the mail and I've been testing it against an internal Terratec Aureon 7.1-Space sound card in my PC, connected to a NAD C 352 amplifier with a pair of B&W DM603S2 speakers. I can't hear a difference. Not that I necessarily expected to; one of the reasons I bought the ODAC is to avoid the loud sound output by the analog out of my sound card when my computer is turned off. Also, it makes me able to have devices without a sound card output sound to my stereo.

One thing that disappointed me though was the noise floor. It's exactly the same as that of my internal sound card.

When nothing is playing on the ODAC, it's silent. Probably because it's not outputting anything. But when I play a WAV file with silence in it, its noise floor goes up to exactly that of the internal sound card. The noise floor of the internal sound card is the same whether I play anything on it or not though.

Interestingly, when I connect the ODAC to my Raspberry Pi, the noise floor disappears almost completely. So as far as I can deduce, noise is being transferred from my PC over the USB cable to the ODAC.

It is likely that what you are experiencing is the windows sound software stack getting in the way. You need to configure a music player such as Foobar2000 to send the data directly to the DAC over USB without windows touching it.

It has been a few years since I have used windows and therefore foobar to play music but a quick google found this link.
Configuring foobar2000 and Windows 7 for digital music playback

Personally I use GNU+Linux as my OS of choice with MPD as my music player. While the learning curve is quite a bit steeper, it is a lot easier to decide what happens to the music. Pushing the bits directly to the DAC is just a matter of editing a config file. If anyone one wants more info on MPD+DAC configuration then let me know. The stuff on the Internets is a minefield for newbies.

[quaeritate]

Originally Posted by swalter

Hi, the quote above is copied from my website and was posted as review from one of my customers.
From his experience the Pi is not able to handle the ODAC with bit perfect output settings.
16bit CD quality seems to work fine with it.

Best Regards, Stefan

I was thinking of trying to put a Pi+ODAC into a custom case, but this comment has given me pause. Was a powered USB hub tested? I am wondering if the problem is trying to power the ODAC directly off the Pi USB.

[swalter]

Originally Posted by quaeritate

I was thinking of trying to put a Pi+ODAC into a custom case, but this comment has given me pause. Was a powered USB hub tested? I am wondering if the problem is trying to power the ODAC directly off the Pi USB.

Hi, above comments have been made almost a year ago, lots of things happened during that time Have a look over here: www.raspyfi.com

[malch]

Just built and tested the O2 from swalter. Added a booster
Thanks

[boris81]

I have the ODAC PCB and I broke it by carelessly handling it while the power was on. I wonder if I can repair it. The L100 inductor gets extremely hot when plugged in and I wonder if replacing it might fix the problem. Is this something worth trying out? What specs should I look for if buying a replacement?

IMG_20140210_220820.jpg

[bbmiller]

I may be looking for a different DAC and headphone amplifier then I thought I would originally get since the ones I've ordered from China do not seem to be coming because the seller is not reliable and PayPal's tells me I may have to file a dispute.

Consequently I was thinking both the Objective2 and ODAC or the combination was looking very desirable to drive my new Sennheiser HD 600s headphones. However I will need an optical audio input on my DAC an USB will not do it for me since I will be using my set up in two places near my computer and across my basement near my television. So in optical audio input is what I will require. So is there any way I can do either a do-it-yourself mod or get a commercially available optical audio to USB converter which would give me a very high quality set up using the ODAC?

Or alternatively could you suggest another DAC with optical audio input designed under the same philosophy of having objective audio and being of good value?

[Clockworktent]

Has anyone had problems with volume control noise with an ODAC?
I have a very nice stepped attenuator from Khozmo but I get crackly noise when adjusting it when the ODAc is selected as input to my passive pre-amp. I get no problems with any other input selected (e.g. TV, alternative DAC) and I get the same with different USB ports and even from my laptop.


I have the ODAC (Rev. B) installed as a bare board in my preamp and was wondering if it needs grounding somehow. I have tried grounding the USB connector, but it made no difference.


Any help or advice would be most welcome!