[Skubasteve]

I'm looking for a chip that will convert 96kHz USB audio into I2S. I've scoured the forums here, and haven't come up with anything. Can anyone refer me to such a chip?

I've looked at the PCM27xx and PCM29xx stuff from TI, but it's all 48kHz max. C

I think the m-audio transit and perhaps Audigy 2NX can handle 96kHz (and the new USB option for the DAC1); does anyone know what USB chips are used in those?

 

[ericj]

You have a lot of 96khz recordings?

 

[Polaris111688]

I think USB does only 48 kHz, unless you have software and drivers to back up the hardware.

 

[amb]

USB 1.1's bandwidth limitation is such that it can't do duplex 96KHz. The M-Audio Transit, for example, will do 96KHz in a single direction only. It will do 48KHz duplex. The only USB 2.0 interfaces that I'm aware of are the E-mu 0404 USB and E-mu 0202 USB.

 

[ericj]

Quote:

Originally Posted by amb /img/forum/go_quote.gif USB 1.1's bandwidth limitation is such that it can't do duplex 96KHz. The M-Audio Transit, for example, will do 96KHz in a single direction only. It will do 48KHz duplex. The only USB 2.0 interfaces that I'm aware of are the E-mu 0404 USB and E-mu 0202 USB.

I suspect that it's not so much the bandwidth as the available isochronous bandwidth + timing issues.

At any rate, there is also the Tascam US144.

CMedia has a few usb2.0 audio codecs available, but they sure don't do 96khz. however, this guarantees that cheezy usb2 audio devices will soon be in the $20 range.

And they'll probably suck. See my RMAA tests of a Turtle Beach Audio Advantage Micro (CM102-A):

http://166.70.233.190/rmaa/Turtle%20...ge%20Micro.htm

Anyway, I still question why somebody who isn't using ProTools all day or testing external devices has any real need for a 96khz dac. Sample rate conversion can ONLY degrade the signal. In fact, unless you're upsampling past the nyquist frequency and then downsampling back down to your target sample rate, it degrades the signal rather a lot.

 

[amb]

Quote:

Originally Posted by ericj /img/forum/go_quote.gif See my RMAA tests of a Turtle Beach Audio Advantage Micro (CM102-A): http://166.70.233.190/rmaa/Turtle%20...ge%20Micro.htm

That's pretty bad indeed!

 

[Magsy]

http://focus.ti.com/docs/prod/folder...tusb3200a.html

http://focus.ti.com/docs/prod/folder.../tas1020b.html

 

[error401]

Quote:

Originally Posted by Magsy /img/forum/go_quote.gif http://focus.ti.com/docs/prod/folder...tusb3200a.html http://focus.ti.com/docs/prod/folder.../tas1020b.html

Wewt for uC programming

 

[Skubasteve]

Thanks for the replies.

Ericj, I don’t currently have 96kHz source material, but I’d like to be able to feed the chip upsampled CD audio (using Secret Rabbit Code or some such algorithm) and perhaps DVD-Audio material. It also seems like a decent way to future-proof my setup, since playback hardware looks to be moving higher-res, which will certainly drive the availability of high-res content.

Amb and ericj, what are the disadvantages to one-way transmission, assuming my music server is dedicated to playing music?

Perhaps a dumb question: why hasn’t anyone taken advantage of the significant bandwidth increase afforded by USB 2.0 and introduced a 2.0 audio chip?

 

[amb]

Quote:

Originally Posted by Skubasteve /img/forum/go_quote.gif TAmb and ericj, what are the disadvantages to one-way transmission, assuming my music server is dedicated to playing music?

Nothing, if the interface is going to be used for playback only. However if you need to do stuff like running RMAA benchmark or something similar, then you need simultaneous record/playback capability.

Quote:

Perhaps a dumb question: why hasn’t anyone taken advantage of the significant bandwidth increase afforded by USB 2.0 and introduced a 2.0 audio chip?

The existence of some USB 2.0 sound cards suggests that there are chips available (although I've not looked to see what specific ones). Perhaps most sound card manufacturers are just slow in catching up with actual products. You might want to look at some of the M-Audio IEEE1394 firewire sound interfaces. Firewire is faster than USB 2.0 and has a synchronous protocol, which is better for low latency.

 

[Regus]

Quote:

Originally Posted by Skubasteve /img/forum/go_quote.gif Perhaps a dumb question: why hasn’t anyone taken advantage of the significant bandwidth increase afforded by USB 2.0 and introduced a 2.0 audio chip?

The current selection of USB 2.0 devices is pretty sparse in any area - I can't find a single MCU that will do hi speed USB - It probably has to do with the 480 Mb/s being a bit much to handle i.e. requirering some pretty modern transistor technology - it does require operating at neraly half a gigahertz and it isn't that long ago that sort of speed was high end CPU teritory.

So in short my guess is the bandwidth increase is too great to have found its way down into mass produced affordable ICs

If they had asked around before designing USB 2.0 they migt have included an extra speed option of around 50-100 Mb/s to support that end of the marked...

 

[ezkcdude]

DIR9001:

http://www.ti.com/lit/gpn/dir9001

 

[ericj]

There's no USB in that audio receiver part.

 

[ezkcdude]

Quote:

Originally Posted by ericj /img/forum/go_quote.gif There's no USB in that audio receiver part.

Yep. My bad.

 

[ericj]

I suspect that existing 96khz usb audio products are all using custom ASICs.

We could probably come up with a high-sample-rate usb-to-i2s solution using something like a Cypress EZ-USB chip, but first you'd have to find someone who knows how to program the things.