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-   -   MiniDSP 2x8 as I2S crossover & DSP? (http://www.diyaudio.com/forums/minidsp/200946-minidsp-2x8-i2s-crossover-dsp.html)

Jokener 21st November 2011 07:03 PM

MiniDSP 2x8 as I2S crossover & DSP?
 
I currently have a computer with I2S outputs.
(Asus Xonar HDAV 1.3 Deluxe, I2S can be grabbed @ a pin header... convenient ^^ )

Now I want to build a DSP/Crossover/DAC solution.
The DAC will likely be an AckoDAC or a Buffalo III, both with I2S inputs.

Can I input a stereo I2S signal on a miniDSP module, then use DSP and XO functionality AND then send a 4-channel (2-way stereo speakers) out via I2S to the external DAC (AckoDAC/Buffalo).

And what miniDSP module do I need to buy for this?
The 2x8 module has 24/96 ADC/DAC capabilities, but I am neither looking to convert anything from analog to digital nor the other way round...
Unfortunately the manuals on the website didn't really clear things up for me.

Thanks in advance for answering my question.

Regards,
Jokener

454Casull 21st November 2011 07:08 PM

You could always email miniDSP and ask them about their I2S handling.

minidsp 23rd November 2011 03:31 AM

@ Jokener,

You could indeed use a miniDSP 2x8 board to perform what you're looking for. i.e. I2S in/out DSP unit. While the unit is Analog out, it obviously goes to a DAC. The I2S lines are actually well labelled on the board so you could "tap" them with some flywires and send them to your external DAC boards. You'd have to know some electronics and have some scope to make sure all these are synched correctly, but it sounds like if you're planning to do that project, you'd know what LRCLK/SCLK/MCLK are.. :-)

Makes sense?

DevTeam

Jokener 23rd November 2011 06:06 AM

@454Casull:
As I said, I have used the Google and came back empty. But I found others with the same question.
And now, if someone uses the G... they find this thread. And the perfect answer.

@miniDSP:
THANKS!
You just won yourselves a new customer :-)
I have some electronics skills and I'll be able to access an oscilloscope for these types of tasks.
And its not like I am asking you to guarantee for the success of this project... that will involve quite some tinkering.
So: question perfectly answered, thank you.

ccclapp 20th March 2012 08:49 AM

Going further with pure digital and external DAC
 
"now, if someone uses the G... they find this thread. And the perfect answer"

...I did just that. THANKS

This concept is exactly what I have been trying to figure out as well. May I followup with a few questions:

1) On the minidsp am I correct that the processing happens in the digital domain and if fed a digital source, there is only a D/A conversion? In other words, to do as discussed, we only need to substitute our DAC, not a ADC, right?

2) I am not as experienced with DIY. If feeding a Buffalo III, can we simply connect to the board(s) using the correct connection locations and header configuration, or is it more complex than that?

3) It seems the miniDSD can receive a i2s digital stream (vs spdif, etc)? If so, could I use the exaU2I usb to i2s converter to feed a much cleaner signal to the mini and bypass its sample rate conversion (and bypass the entire Digi-FP going direct t the minidsp with i2s)

www.exadevices.com > exaU2I > Overview

4) What is the purpose of the oscilloscope.

5) Have you successfully done this mod? What are your comments about it?

Thanks

curryman 20th March 2012 11:24 AM

1) Processing (EQ, crossover, delay, etc.) indeed works completely in the digital domain, so conversion will only be necessary at the output (DAC).

2) In general you "only" have to connect wires to the correct positions on the boards, thats right. However some technical knowledge is very helpful to do thinks right. As DevTeam said, you should know how I2S works and what LRCLK/SCLK/MCLK are!

3) The DSP core on the miniDSP is running on a fixed samplerate (e.g. 96kHz for 4x10 plugin). Therefore you have to make sure to feed the I2S signal with the correct samplerate to the DSP. Therefore the sample rate converter is used on the Digi-FP and miniDIGI. Don't know if exaU2I can be configured to output a fixed samplerate?

4) That refers to debugging that might be necessary to get I2S stuff running. With the Scope you can watch all the clock signals for troubleshooting.

5) I haven't done this mod for the 2x8 (though I did some I2S stuff), but some others already combined miniDSP with twisted pear DACs via I2S. But to be honest, reading your questions I wouldn't recommend you to go this route unless you are willing to learn a lot about digital signal routing and risc one or more boards during troubleshooting. Getting correct clocks and making sure everything works well is quite tricky ;)

hope this helps...


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