[Infinitas]: USB Audio Class 2 Interface, 32 in, 32 out, DSP

[rkn80]

Good evening,

I went a long way, did a lot of research and development and now the dream came true: My DIY multichannel USB audio interface is alive! Actually it is the descendant of my earlier AD/DA-project years ago.

The project "Infinitas" still incorporates the modular design (see picture). First there is the interface board. The features are:
USB connection for UAC2 operation exposing 32 inputs and 32 outputs to the computer. In a first version of this board I tried to implement the UAC2 stuff on a generic MCU, now I switched over to XE216 by XMOS which turned out to be the cheaper solution. All audio streams are routed to a MachXO2 for signal distributing/routing. The MachXO2 either routes an audio stream to the DSP or to the expansion headers.
There is an optional DSP on this board. It is an ADAU1452. This can be easily programmed by SigmaStudio.
As I said the DSP is only an option.
The board has wordclock in and out. It uses a CS2100 for the PLL.
To this interface board you can connect up to 32 inputs and 32 outputs. For testing (s. picture) I have connected my new ADC/DAC board with 8 balanced audio inputs and 8 balanced audio outputs utilizing AKM4458 and AKM5558.
Since this project has a strong connection to the freeDSP project the expansion headers use the freeDSP I2S expansion header pinout.

Currently I am busy with building the next ADC/DAC board to expand the setup to 16 I/Os.

Since the USB implementation is UAC2 it works driverless for macOS and Linux. For Windows you will need one of these open source ASIO drivers. I haven't tested this yet, but I will soon.
Edit: It does work with the usbaudio2 driver of Windows 10 together with asio4all. No additional driver needed.

Of course some more expansion board are needed (AES, ADAT etc.). I think I'll make an ADAT board for it next. However, I'ld like it to see that you start designing your own expansion boards. Therefore, I am planning to publish the project on github under a open hardware license.

Anyway, if there is enough interest we can organize a group buy of the already existing boards.

Raphael

 

[zamproject]

Hello Raphael

That's the new DIY millennium ...

All hand soldering ?

Looking forward, so interesting !!!

Best
Zam

 

[kvintus]

Impressive! Following this with great interest.

I am absolutely interested in buying PCBs and building one of these.

/Anders

 

[rock soderstrom]

Impressive! Following this with great interest.

I am absolutely interested in buying PCBs and building one of these.

/Anders

+1!

 

[Rocinante]

I'm in.  Although how much SMD soldering are we talking about?

 

[chefducuisine]

Interested.
Do your 'old' ad/da boards as well?

 

[rkn80]

I'm in.  Although how much SMD soldering are we talking about?

Very stressless. I did both boards on two saterdays afternoons, thus one afternoon per board including basic testing etc. I did not use any special tools, only a solder iron with  a fine tip and a cheap hot air solder station (but that is not really needed).

 

[rkn80]

Interested.
Do your 'old' ad/da boards as well?

Yes they do. Depending on desired configuration you may have to change them from i2s operation to tdm8 operation.

 

[MetalD]

I am very very interested

 

[Whoops]

Hello Raphael,
congratulations for your work and developments.

 

[lame_turtle]

This is fantastic.

Totally interested in building one of those.

 

[electric_diaries]

Awesome work! I have been following your other threads with great interest.

I would also be very interested in getting one. Maybe if there is enough interest we could do a group buy with SMD stuff already soldered, since it doesn't cost that much extra these days.

 

[TheJames]

I'm interested in this.

With that setup pictured above, you have 8 channels in, 8 channels out on DB25, and then a digital I/O card with USB and wordclock?  Then all you need is a PSU and box and you're ready to roll?

Estimated cost for the boards?

 

[iampoor1]

Very interested as well. Estimated cost?

 

[Murdock]

Sounds great!
Depending on the price, I would also be very interested in a 32x32 Interface.

 

[rkn80]

Hello,

I am very happy that there is (still) interest in this project after a so long R&D time.
Here are some prices for the components per board:
Mainboard: ~90€ (without the DSP option it becomes cheaper)
AD/DA-Board 8in, 8out: ~90€
Both prices do not include any quantity discount. I ordered from digikey.
PCBs are on top. PCB prices depend on quantities much more then the components. I think, if you assume 5-10€ per PCB for low quantities, you are on the save side.
So far the cost estimation.

Regarding the SMD stuff: I think we could arrange something like mounting the semiconductors that you only have to do the resistors and capacitors. Please note: The current laws and regulations in the EU make it impossible to sell ready-to-run boards. This would require all the CE/EMC/RoHS/WEEE certification processes eating a lot of money.

I am still waiting that digikey delivers the DACs for the next AD/DA boards. The DACs are currently out of stock and reordered. 
Want to expand my prototype to 32 channels in and out.

R.

 

[rkn80]

With that setup pictured above, you have 8 channels in, 8 channels out on DB25, and then a digital I/O card with USB and wordclock?  Then all you need is a PSU and box and you're ready to roll?

Exactly!

 

[lame_turtle]

Price is actually really nice. 90 euros for 8 channels being able to expand to 32.. It is crazy, and word clock addition takes it even further. I will be building one of those for sure. Smd soldering is ok with me and I would not be interested if it does increase the cost substantially . Any info on conversion quality ?

This is an amazing project.

 

[mhelin]

The ADC/DAC board contains both chips? So there is no separate ADC board (and it can't be just cut out)?

 

[rkn80]

Any info on conversion quality ?

AKM specifies the converters as follows:

ADC: S/N 118dB, S/(N+D) 106dB, 32bit
DAC: S/N 115dB, THD+N -107dB, 32bit

I am running them at 48kHz. Higher sample rates are possible but may require some modifications of the UAC2 firmware, which I have not done yet. But volunteers are welcome since I want to make it open source.

The ADC/DAC board contains both chips? So there is no separate ADC board (and it can't be just cut out)?

Yes, there is only one board for ADC/DAC. But you can easily leave out the option you don't want and only order and mount e.g. the DAC.

R.