Want to make a USB sound card

[Plecto]

Hi. I really want to be able to make a USB soundcard, that is, I would like to be able to make audio amplifier with USB input! The task is simple really, USB in one end, PCM out the other. I believe I need a MCU with a USB interface and then it's just down to some C-code I can copy from somewhere? One question I have when it comes to live transfer of sound is how this is timed? It's very important that the bitrate is constant, right? So I have to be careful if I want the MCU to handle some some additional task so not to cause jitter? I don't really need to (or want to) understand how a USB sound card really works, I just want the PCM in my lap so I can handle it from there Is this hard to accomplish?

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I came across this thing: http://www.ti.com/lit/ds/sbfs036a/sbfs036a.pdf

It seems to do everything I ask for with little or no configuration (it even includes an internal audio amplifier). I've read a little bit of the datasheet and I see that it will require some work to understand this thing properly. This was the only USB interface audio amplifier I could find on mouser, are there other chips out there that are cheaper and simpler?

 

[josiphal]

Of course, this is possible, but if you have some very good reason for doing it.

If you just want to build DAC/preamp/amp to have USB interface to PC, use PCM2707 or something similar. Connect I2S output from PCM directly to (for example) TDA1543 and you will have good sounding PC device.

 

[Plecto]

Alright, I think I'll go for this solution and see. One last question, why would I need a DAC like the TDA1543? The PCM2704 has an internal DAC and even an internal amplifier meant to drive headphones.

 

[josiphal]

Alright, I think I'll go for this solution and see. One last question, why would I need a DAC like the TDA1543? The PCM2704 has an internal DAC and even an internal amplifier meant to drive headphones.

Yes, PCM2707 or similar devices, have all you need for DIY USB sound card for drive headphones. Devices with I2S are popular in DIY audio community, because they can connect directly to I2S DAC chips, without I2S -> S/PDIF -> I2S conversion. TDA1543 is good sounding device, that cost less than nothing (not only chip, but complete NON-OS DAC), hard to beat sound quality / price ratio.

PCM2707 can handle up to 48 kHz / 16-bit audio, so higher sampling / resolution will be scaled down on PC side.