What 2x4 crossover for Raspy ?

[blo06]

Hello guys,

I'm looking to mate my Raspy with a crossover to make an active stereo system.
I'm looking for a 2x3 (or 2x4) system.

I've browsed the net and found out that problems could appear because of clock rate or other critters...

Do you have any recommendations or experience on that ?
Does a miniDSP could do the trick ? Which one ?
USB or i2s ?
What to do or not do ?

Thanks for your answers !

Blo

 

[CharlieLaub]

AFAIK, MiniDSP does not offer a product that includes ADC and can work with the Pi.

Asus Xonar U7 could work well for your needs. Give that a look. I have used one but had some noise issues. It's USB bus powered, and I think the culprit was the Pi's USB PWR.

There are some pro audio interfaces with USB interfaces that you could try. The Behringer UMC404HD has 4-in/4-out and is not expensive. Check to make sure these are class compliant for compatibility, but I believe this one will work out of the box when you plug it in.

Both of these have similar max output levels of just over 1Vrms. Make sure you check the input sensitivity of your power amps. IF they are higher, you will never be able to make them reach full power.

I have a Behringer FCA610 running on a Pi and powering a system. This might also be something to look into for its superior specs, but cost is higher...

 

[Jerms]

Cheapest is to use Charlie Laub's ACDf filter set on Linux and use a CM6206LX USB soundcard. That would get you a 6 channels @ 44.1/48KHz.

I use this solution and it works fine. However, I do have digital artifacts coming through (evident in the quiet between tracks). I have thought to use a "data only" connection to the CM6206LX and power it throuogh a powered hub. I haven't tried this yet though.

The learning/frustration curve can be steep however, especially if you are not already familiar with programming.

For a 2.1 system, try the Allo Kali and Piano 2.1?

 

[blo06]

I'm afraid the Raspi is not powerfull enought for this task...
That's why I'm looking for an external DSP.
You should use bigger computer ?


Yes, the Allo Kali and Piano 2.1 look good but don't make it for a 3 way stereo.


Thanks for your answers !

 

[CharlieLaub]

I'm afraid the Raspi is not powerfull enought for this task...

You are 100% wrong about that.

Processing many, many IIR filters is not a problem for the R-Pi. If anything, the bottleneck is data I/O throughput. The Pi has no audio "input" so you have to find one that you can add on. For me, this means going for USB soundcards, which have stereo inputs and 6-8 outputs (e.g. 5.1 or 7.1 channel). You won't find high sample rates for these peripherals, usually 48kHz or sometimes 96kHz is about the max. This doesn't bother me at all - I am interested in higher and higher sample rates, DSD, etc.

The soundcard specs that you should pay attention to are the noise floor and the max output level (in Volts, RMS) of the DAC channels. The noise floor can be USB bus power dependent, try a hub or USB isolator if noise is too high.

 

[blo06]

Hi,

thanks for the inputs.

I've browsed something like you propose :
Raspberry Pi Music Server With Built-in Crossover and DSP: 12 Steps (with Pictures)
which is a Raspi with LASPA plugins.

and
Tutorial: Raspberry Pi as Music Server, DSP, and Crossover

Looks good but need time to dig in.
And time is scarse !!