[ruffrecords]

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

[NOON]

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

[Rochey]

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

[gyraf]

..the hard part is probably the USB drivers, unless you're going for very basic resolution and features..

/Jakob E.

[ruffrecords]

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

[Rochey]

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

[ruffrecords]

@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

[Rochey]

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.

[ruffrecords]

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

[Rochey]

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.

[ruffrecords]

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

[Rochey]

pcm2902, pcm2903, pcm2906, pcm2900

[elskardio]

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

[mhelin]

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.

[ruffrecords]

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

[Rocinante]

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.

[Rochey]

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

[cyrano]

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.

[Rochey]

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?

[Rocinante]

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.

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