Hi,
I'm wondering if it's possible to build (DIY) an USB DAC/soundcard
with 2 inputs and 2 outputs with a DAC with a sampling frequency of 192Khz.
Has anyone tried to do something close?
I'm wondering if it's possible to build (DIY) an USB DAC/soundcard
with 2 inputs and 2 outputs with a DAC with a sampling frequency of 192Khz.
Has anyone tried to do something close?
It's easy to make a 44.1/16 DAC using a PCM270x/290x chip from TI - these include the USB interface and software layer, isochronous clock recovery and everything and they're natively supported by Windows.
No such publically available chip exists for 24/192 right now, and I don't believe that the Windows USB soundcard driver supports these high sampling rates anyhow. This means building lots of custom hardware (think Cypress USB chip, separate PLL, PLD for handling I2S/SPDIF reformatting, etc), writing your own soundcard driver for windows, and lots of other evil things. It's a ton of effort.
Best to wait for TI to come out with a successor to their USB audio chips. 😀
No such publically available chip exists for 24/192 right now, and I don't believe that the Windows USB soundcard driver supports these high sampling rates anyhow. This means building lots of custom hardware (think Cypress USB chip, separate PLL, PLD for handling I2S/SPDIF reformatting, etc), writing your own soundcard driver for windows, and lots of other evil things. It's a ton of effort.
Best to wait for TI to come out with a successor to their USB audio chips. 😀
gmarsh, thanks for your reply!
There are some commercial USB sdcards that allow 192Khz, but I've never seen a DIY one either!
How do the more usual 44,1khz using a PCM270x/290x chip from TI sound?
How do they compare to commercial soudcards?
There are some commercial USB sdcards that allow 192Khz, but I've never seen a DIY one either!
How do the more usual 44,1khz using a PCM270x/290x chip from TI sound?
How do they compare to commercial soudcards?
Alexnick said:
In general they have opamps built in. They sound decent for what they are, but are not spectacular. However, you can use the spdif output (2902, 2704, 2706, 2707) or the i2s output (2706, 2707) and build quite a nice DAC (http://www.ecp.cc/NOS-USB-DAC.html)
dsavitsk, thanks for the link!
How does this DIY sdcard compare with commercial sdcards in terms of SQ?
You say that I could build that sdcard just tu use its S/PDIF output and use an external high quality DAC, right?
Has anyone tried it?
Are there rumors that Texas Instruments are gonna lanuch a new generation of USB audio chips?
How does this DIY sdcard compare with commercial sdcards in terms of SQ?
You say that I could build that sdcard just tu use its S/PDIF output and use an external high quality DAC, right?
Has anyone tried it?
Are there rumors that Texas Instruments are gonna lanuch a new generation of USB audio chips?
Alexnick said:
Well, I designed it, so I am biased as to how good it sounds. To me, however, it sounds better than any other sound card I've used.
Alexnick said:
The pcm2706/7 can output either spdic or i2s depending upon voltage on one of the pins. That particular card does not have spdif output. Some other chips are only spdif (or analog). For a usb to spdif project, look here (http://www.ecp.cc/usb-spdif.html). For a simple usb dac using the analog output, here is a thread on one currently being worked on. (http://www6.head-fi.org/forums/showthread.php?t=139368)
I've not heard it. I have a couple of the previous versions, and they are pretty good. Here is a review I wrote: http://www.ecp.cc/gud.html
I should mention a couple of things though. It is an old review and I have learned a lot since then. I'm not quite as much of a newb as I was when I wrote the article. Compared to the one I linked above (the NOS USB DAC) the one in the review is not nearly as good. I would assume that Alf's that you linked to is a little better than the one n the review, but basically the same as it is basically the same circuit.
All that is to say that it is worth looking into. You should expect it to be pretty good for the investment, but don't expect it to be a giant killer.
I should mention a couple of things though. It is an old review and I have learned a lot since then. I'm not quite as much of a newb as I was when I wrote the article. Compared to the one I linked above (the NOS USB DAC) the one in the review is not nearly as good. I would assume that Alf's that you linked to is a little better than the one n the review, but basically the same as it is basically the same circuit.
All that is to say that it is worth looking into. You should expect it to be pretty good for the investment, but don't expect it to be a giant killer.
I am interested in interfacing an A/D converter via the USB port.
Is there a chip specifically designed for this purpose?
Tom
Is there a chip specifically designed for this purpose?
Tom
Alexnick said:
USB 1.1 does not support rates higher than 24/96 for its audio profile (the part of the standard that allows all USB 1.1 audio devices to magically work without a special driver) and USB 2.0 doesn't have an audio profile at all. USB audio devices that support 24/192 are USB 2.0 and require special drivers, just like FireWire audio devices.
Good luck on your quest.
bb
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