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General Discussions => Truth Table => Topic started by: ruffrecords on July 27, 2020, 04:40:59 PM

Title: single-chip USB stereo audio codec with USB
Post by: ruffrecords on July 27, 2020, 04:40:59 PM
If I wanted to add USB I/O to a tube mixer, which chip or ready made module would you recommend I use?

Cheers

Ian
Title: Re: single-chip USB stereo audio codec with USB
Post by: NOON on July 27, 2020, 05:50:08 PM
TI does a range of USB interface chips. They're only max 48k sampling and specs aren't exactly the highest end, but easy to use.

https://www.ti.com/audio-ic/converters/usb/products.html
Title: Re: single-chip USB stereo audio codec with USB
Post by: Rochey on July 27, 2020, 09:58:12 PM
Ian,

I was the marketing guy for the TI chips. They are workhorses that work in just about anything, but they do burn more power than other devices on the market.

I strongly suggest PCM2906C - the C revision specifically.

I'll answer what I can.

/R
Title: Re: single-chip USB stereo audio codec with USB
Post by: gyraf on July 28, 2020, 03:08:00 AM
..the hard part is probably the USB drivers, unless you're going for very basic resolution and features..

/Jakob E.
Title: Re: single-chip USB stereo audio codec with USB
Post by: ruffrecords on July 28, 2020, 04:02:46 AM
Ian,

I was the marketing guy for the TI chips. They are workhorses that work in just about anything, but they do burn more power than other devices on the market.

I strongly suggest PCM2906C - the C revision specifically.

I'll answer what I can.

/R

I looked at the TI chips. They look easy to use but they only go up to 48K and 16 bits. Not sure if my customers would be OK with that. Farnell stocks the TI evaluation  board for it but it costs £154 which seems a bit steep for three chips and a crystal on a PCB. I wonder if the PCB layout is available, then I could build my own. 

What about the PCM3060?

Cheers

Ian
Title: Re: single-chip USB stereo audio codec with USB
Post by: Rochey on July 28, 2020, 02:16:50 PM
PCM3060 doesn't do USB.
There are dozens of PCM2900 boards on aliexpress. way cheaper than the TI board.

You are right that 48K/16bit may not work. It is VERY easy though. Any dedicated customers would have better external converters than what you can offer.

your other option may be something like a:
https://www.minidsp.com/products/usb-audio-interface/usbstreamer

Along with a nice PCM4202/4 ADC and PCM4104 DAC based design.

There's likely newer ADC's and DAC's you can use these days :)

/Rochey


Title: Re: single-chip USB stereo audio codec with USB
Post by: ruffrecords on July 28, 2020, 04:28:17 PM
@Rochey,

You may well be right. I was thinking first of having it as an option in the upcoming Poor Man's Tube Mixer so I expect a poor man will not quibble to much about 48K/16.

I will check out the cheapo PCM2900 boards. Any known good ones?

Cheers

Ian
Title: Re: single-chip USB stereo audio codec with USB
Post by: Rochey on July 28, 2020, 04:40:11 PM
I will check out the cheapo PCM2900 boards. Any known good ones?


Most of them are copy/paste's of the datasheet ref design. Look for one with decent reference caps.
Title: Re: single-chip USB stereo audio codec with USB
Post by: ruffrecords on July 28, 2020, 05:02:13 PM
Most of them are copy/paste's of the datasheet ref design. Look for one with decent reference caps.

PCM2900 board search at Aliexpress returns no relevant results for me. Odd.

Cheers

Ian
Title: Re: single-chip USB stereo audio codec with USB
Post by: Rochey on July 28, 2020, 05:15:16 PM
PCM2900 board search at Aliexpress returns no relevant results for me. Odd.

Cheers

Ian

They are all based on the same design - PCM2902, PCM2903 --
https://www.aliexpress.com/item/1454024935.html?spm=a2g0o.productlist.0.0.3adc52edh3vZdv&algo_pvid=2ba3e781-fe37-41be-8aec-5627f2b240a4&algo_expid=2ba3e781-fe37-41be-8aec-5627f2b240a4-0&btsid=0ab50f6215959709448942016ea2d8&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

your mileage may vary. Please solicit others information as well as mine. :)
Title: Re: single-chip USB stereo audio codec with USB
Post by: ruffrecords on July 29, 2020, 03:40:48 AM
They are all based on the same design - PCM2902, PCM2903 --
https://www.aliexpress.com/item/1454024935.html?spm=a2g0o.productlist.0.0.3adc52edh3vZdv&algo_pvid=2ba3e781-fe37-41be-8aec-5627f2b240a4&algo_expid=2ba3e781-fe37-41be-8aec-5627f2b240a4-0&btsid=0ab50f6215959709448942016ea2d8&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

your mileage may vary. Please solicit others information as well as mine. :)

exactly what search term are you using. I cannot seem to get anything like that using any combination of usb audio module PCM290X

Cheers

Ian
Title: Re: single-chip USB stereo audio codec with USB
Post by: Rochey on July 29, 2020, 11:09:15 AM
pcm2902, pcm2903, pcm2906, pcm2900
Title: Re: single-chip USB stereo audio codec with USB
Post by: elskardio on July 30, 2020, 10:52:51 AM
Hi Ian,

I found a little board made by Versalogic based on the PCM2906C. It's available at Digikey:
https://www.digikey.ca/en/products/detail/versalogic-corporation/VL-ADR-01S/5222061

Also someone is selling a nice kit on ebay for a design around the older PCM2906 (usb 1.1):
https://www.ebay.co.uk/itm/USB-audio-sound-card-SMT-KIT-with-analog-and-S-PDIF-in-out-based-on-TI-PCM2906/112817850594?hash=item1a4477c8e2:g:rYEAAOxy-WxTB-6A

At last, you can get the Gerber files for the original TI development board at the following address:
https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/6/PCM290x_5F00_RevC_2D00_ed.zip

I ordered the Versalogic board to test the design first. I'll report back
Cheers
Gabriel
Title: Re: single-chip USB stereo audio codec with USB
Post by: mhelin on July 30, 2020, 03:10:38 PM
Not single chip solution but supports 24-bit audio:

https://www.silabs.com/interface/usb-audio-bridges/device.cp2615

Unfortunately this seems to be only half-duplex in 24-bit mode  :(

The "industry standard" USB audio interface these days seems to be an XMOS controller and firmware with a codec (Cirrus or AKM), or with separate ADC and DAC chips. For an example the cheap Soundcraft Notepad FX series small USB mixers use them (the codec is CS4270, there are two of them in the Notepad 12FX model). The 3rd gen Focusrite Scarletts use CS4272 codecs.
Title: Re: single-chip USB stereo audio codec with USB
Post by: ruffrecords on July 30, 2020, 05:01:51 PM
Not single chip solution but supports 24-bit audio:

https://www.silabs.com/interface/usb-audio-bridges/device.cp2615

Unfortunately this seems to be only half-duplex in 24-bit mode  :(

The "industry standard" USB audio interface these days seems to be an XMOS controller and firmware with a codec (Cirrus or AKM), or with separate ADC and DAC chips. For an example the cheap Soundcraft Notepad FX series small USB mixers use them (the codec is CS4270, there are two of them in the Notepad 12FX model). The 3rd gen Focusrite Scarletts use CS4272 codecs.

Interesting. I was wondering if anyone would know what other mixer manufacturers are using. Thank you. That is very useful information.

Cheers

Ian
Title: Re: single-chip USB stereo audio codec with USB
Post by: Rocinante on July 30, 2020, 08:19:06 PM
I think drivers are going to be an issue here as well. I dont think most DAW's will see it as a generic device. Itll probably require some programming and correct me if I'm wrong but communication with whichever DAW you are going to use.
Title: Re: single-chip USB stereo audio codec with USB
Post by: Rochey on July 30, 2020, 09:58:31 PM
The are audio class compliant devices. They will be seen as generic audio interfaces that can support 16bit 48kHz (and lower)

These things have been in Behringer UCA202 for YEARS. They may have finally been replaced.
I don't say that as a sign of audio fidelity, more as a sign of a product that requires minimum support.

/R
Title: Re: single-chip USB stereo audio codec with USB
Post by: cyrano on July 30, 2020, 10:17:04 PM
USB compliant interfaces go up to every sample rate and bit-depth the OS supports. That's 192 kHz, 24 bit in practice.

Even the Behringer ones have supported that for ages. The UMC404 was very popular on Linux exactly for that reason.
Title: Re: single-chip USB stereo audio codec with USB
Post by: Rochey on July 31, 2020, 12:28:28 AM
USB compliant interfaces go up to every sample rate and bit-depth the OS supports. That's 192 kHz, 24 bit in practice.

Even the Behringer ones have supported that for ages. The UMC404 was very popular on Linux exactly for that reason.

Next Time you work alongside the original pcm290x design team, give me a call.

Audio class compliance means if the silicon reports the capability, that it can go up to those rates.

Pcm29xx was designed in the days of 11Mb/s usb. Everything from the USB rate, to the Spact pLL clock recovery circuits Limit the device to 48kHz.
The original class compliance for usb1.1 audio (which was grandfathered into 2.0)  worked like a dream and continues to do so.

I do wonder what they used for the 404. The dice2 chip?
Title: Re: single-chip USB stereo audio codec with USB
Post by: Rocinante on July 31, 2020, 01:46:00 AM
So one doesn't need drivers for various DAW's?  The DAW would see a 2 - 8 channel device?  Is 16bit 48k acceptable?  Most DAW's run at 24bit  or 32bit floating and up to 192k.  I'm not being a smartass just curious. I have read that to get full integration one would have to contact the DAW company.  Hence the drivers not working with some DAW's. I personally would want the ability to switch bit and sample rates especially if it were coming from a tube mixer. I'd want 24bit 48 or 96k.
Title: Re: single-chip USB stereo audio codec with USB
Post by: ruffrecords on July 31, 2020, 04:46:50 AM
So one doesn't need drivers for various DAW's? 

I would have thought not. The operating system requires or provides drivers for the hardware so it can provide a defined interface to applications (DAW software). The DAW has no knowledge or direct connection with the hardware. Some USB devices are so common, like mice, keyboards and ordinary audio input/output,  that nearly all hardware complies with the requirements of a single Class driver. I think this now extends as far as 24 bit 192KHz devices.

There will always be some odd bits of hardware that require their own specific drivers but the trend is definitely towards driver standardisation.

Cheers

Ian
Title: Re: single-chip USB stereo audio codec with USB
Post by: gyraf on July 31, 2020, 05:15:02 AM
Aah, that is a great development if so - I was under the impression that the generic usb audio drivers would not support anything north of 48/16

/Jakob E.
Title: Re: single-chip USB stereo audio codec with USB
Post by: mhelin on July 31, 2020, 08:12:36 AM
I do wonder what they used for the 404. The dice2 chip?
They used and still use (in 404HD which is identical with original 404 having new firmware which can also be used to upgrade 404 to support 192 kHz sample rate) XMOS controller with Cirrus codecs.

Actually you could use almost any ARM Cortex M4 and above microprocessors to implement the USB stack, there are many USB DACs on market using Atmel parts (Amanero DAC, https://amanero.com/), but you can find some implementations for STM as well (search github for an example). I think someone was/is working on Teensy 4.x to add USB audio interface support as well.

Windows 10 already has driver support for USB Audio Class 2.0, don't know if they support multichannel I/O though, might be you will need the Thesycon drivers. Linux and Mac OS are fully class 2.0 compliant.
Title: Re: single-chip USB stereo audio codec with USB
Post by: ruffrecords on July 31, 2020, 08:31:58 AM
I am a little concerned about a USB powered device creating an earth loop. Would it be possible to use, for example a Cirrus codec powered from the mixer supply optically coupled to a USB powered XMOS interface thereby maintaining galvanic isolation?


Cheers

Ian
Title: Re: single-chip USB stereo audio codec with USB
Post by: cyrano on July 31, 2020, 09:28:54 AM
Optical spdif, eg TosLink?

You'd need one in, one out, of course. But perfect isolation. One of the reasons i'm an ADAT nut :D
Title: Re: single-chip USB stereo audio codec with USB
Post by: cyrano on July 31, 2020, 09:46:32 AM
Next Time you work alongside the original pcm290x design team, give me a call...

I do own a bunch of USB 1.1 compliant devices. And all of those work perfectly with Linux or MacOS. Some are 6/2, some 2/6 @ 48 kHz. These can only do 96 kHz with a 2/2 config. The Behringer FW interfaces also support FW audio class operation.

I also have a number of USB 2 audio class compliant devices. And some of those support 96 kHz. Not 192, as they are somewhat older.

I use all of them @48 kHz, but I've tested it. Most of these devices were orphaned, because their owner couldn't get them to work on Windows...

The only reason I keep them, is because once in a while I can give them to someone and they don't end up on the big pile.

I've bought the stick type USB thingies by the dozen, for projects. But I can't give you a link, cause that was a while ago and <5$ products tend to change a lot.

They all work on Linux and MacOS. Even some of these support higher bitrates, these days. Some even have a DSP, that's not always used. But they are typical one-chip solutions of lesser known (for me at least) Chinese brands. Some of these sound pretty OK, for their price. Some have DC on the output, cause, you know, a cap there costs 5 cents.
Title: Re: single-chip USB stereo audio codec with USB
Post by: winner on July 31, 2020, 10:13:19 AM
I suggest to use "c-media108" although it is a 48000 chip, but it has a USB interface, the most important thing is that it is very cheap, MAC/WINDOWS is free of drivers, and has I2S signal output, to external DAC and external ADC I2S signal Input, SPDIF signal output, external DAC is CS4398, CS4398 is also a cheap and easy-to-use thing; the total signal link USB->CM108AH->I2S->CS4398->DAC
Title: Re: single-chip USB stereo audio codec with USB
Post by: ruffrecords on July 31, 2020, 05:11:51 PM
Optical spdif, eg TosLink?

You'd need one in, one out, of course. But perfect isolation. One of the reasons i'm an ADAT nut :D
Not necessarily - I was thinking I2S sources drive the LED in an opto-coupler the outputs of which feed the corresponding I2S input on the other device. A bit like the way feedback is galvanically isolated on an SMPS.

Cheers

Ian
Title: Re: single-chip USB stereo audio codec with USB
Post by: volker on July 31, 2020, 05:19:42 PM
There are special ICs for that purpose: https://www.analog.com/en/analog-dialogue/articles/digital-isolators-in-medical-and-industrial-apps.html
Title: Re: single-chip USB stereo audio codec with USB
Post by: ruffrecords on July 31, 2020, 05:31:02 PM
There are special ICs for that purpose: https://www.analog.com/en/analog-dialogue/articles/digital-isolators-in-medical-and-industrial-apps.html

Excellent, so you can easily galvanically isolate the USB bus.

Cheers

Ian
Title: Re: single-chip USB stereo audio codec with USB
Post by: mhelin on August 01, 2020, 11:20:48 AM
Not necessarily - I was thinking I2S sources drive the LED in an opto-coupler the outputs of which feed the corresponding I2S input on the other device. A bit like the way feedback is galvanically isolated on an SMPS.

Cheers

Ian
SI8662BC will do the job...
Title: Re: single-chip USB stereo audio codec with USB
Post by: abbey road d enfer on August 02, 2020, 12:53:55 AM
Excellent, so you can easily galvanically isolate the USB bus.

Cheers

Ian
https://www.amazon.fr/GeeekPi-ADUM3160-Isolateur-Isolement-Protection/dp/B07QPN951P/ref=sr_1_6?adgrpid=71422994049&dchild=1&gclid=Cj0KCQjwpZT5BRCdARIsAGEX0zlcMutqY4kRnrQ8L876jE6LPy4-Ljg_5X7ByyGmEuifc32FIhql8TgaAoGHEALw_wcB&hvadid=341734158678&hvdev=c&hvlocphy=9056208&hvnetw=g&hvqmt=b&hvrand=10541068217829121468&hvtargid=kwd-300796253219&hydadcr=7528_1752999&keywords=usb+power+isolator&qid=1596343811&sr=8-6&tag=googhydr0a8-21
Title: Re: single-chip USB stereo audio codec with USB
Post by: ruffrecords on August 02, 2020, 04:18:04 AM
https://www.amazon.fr/GeeekPi-ADUM3160-Isolateur-Isolement-Protection/dp/B07QPN951P/ref=sr_1_6?adgrpid=71422994049&dchild=1&gclid=Cj0KCQjwpZT5BRCdARIsAGEX0zlcMutqY4kRnrQ8L876jE6LPy4-Ljg_5X7ByyGmEuifc32FIhql8TgaAoGHEALw_wcB&hvadid=341734158678&hvdev=c&hvlocphy=9056208&hvnetw=g&hvqmt=b&hvrand=10541068217829121468&hvtargid=kwd-300796253219&hydadcr=7528_1752999&keywords=usb+power+isolator&qid=1596343811&sr=8-6&tag=googhydr0a8-21

Thanks Abbey. I had no idea such things existed.

Cheers

Ian