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Calling Acourate Experts

March Audio

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I am considering purchasing Acourate and have a specific question.

Background to this is I am building a set of 3 way DSP speakers. they have been a long time coming as I havent until recently settled on the dsp hardware.

Initial idea was based on a Minidsp nanoSHARC dsp with Twisted Pear DACS. Digital input from USB, Optical and analogue from a TI PCM4222EVM board. However I wasnt entirely satisfied with the sound, difficult to articulate the problem, and came to the conclusion it might be something to do with the minidsp ASRC converting everything to 96kHz.

Anyway recently came across this Soekris DAC http://soekris.dk/dam1021.html and its sound floats my boat.

It also has the advantage that it has a Spartan 6 FPGA on board which is used to perform the AA filtering and oversampling. This has spare filter slots available that can be used for crossovers. Perfect I can ditch the minidsp and make things much simpler. Yay! :)

Now, my knowledge of DSP filtering is limited. I can design the basic crossover filters by taking the biquad out of the minidsp software

upload_2017-3-12_11-58-47.png


One issue that has sprung to mind is the time alignment of the drivers. In the minidsp there is a seperate delay (ms) input. The Soekris DAC does not have this feature and speaking to the designer the DSP functionality will not be developed further to include simple interface like the minidsp. However he did allude to the fact that the delays can be performed by the filtering.

OK, so reading about Acourate, if I understand correctly, I see it can perform driver time alignment as part of the filtering. My question is will it create a filter output that is compatible with the Soekris DAC?

The DAC format is initially a txt file with IIR and FIR filter coefficients which gets converted by a utility into a suitable format to load into the FPGA.

An example is here http://www.soekris.dk/download/dam1021/1021filt_104.txt

Can anyone shed any light on if this is going to work? I didnt really want to shell out on Acourate until confirmed.

Thanks
 
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hvbias

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Someone posed this question to the Acourate group I think last month, just wondering if that was you? I'm doing multichannel as well with DSP crossovers and I had written off multiple DAMs being compatible with Acourate.
 
OP
March Audio

March Audio

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One and the same :)

The upshot is the dams dont have the processing power to deal with the Acourate FIR filters, notvenough taps. However there is no reason you cant use them as the system dacs. Alternatively do IIR filters onboard the damms but that isnt ideal.

I took the plunge and bought accourate and yesterday tested it out on my existing system using Roon to perform the convolution. Have to say I am very impressed with the results.

Although I didnt want to go down this path initially I will be building a seperate box to house 3 damms for the 6 channels for the 3 way speakers. I am fairly convinced a RPI can run this and will testing that out as a Roon endpoint.

You can use a minidsp usbstreamer to provide 8 i2s outputs

https://www.minidsp.com/products/usb-audio-interface/usbstreamer
 
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DonH56

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What are "damms" in this context? I feel like when I started my new job dealing with raid-on-chip processors and discovered ROC did not mean "radar operations center"...
 

RayDunzl

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Blumlein 88

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Digital analog music module???

I had the same question.
 

hvbias

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I'd never thought about what it stood for.

One and the same :)

The upshot is the dams dont have the processing power to deal with the Acourate FIR filters, notvenough taps. However there is no reason you cant use them as the system dacs. Alternatively do IIR filters onboard the damms but that isnt ideal.

I took the plunge and bought accourate and yesterday tested it out on my existing system using Roon to perform the convolution. Have to say I am very impressed with the results.

Although I didnt want to go down this path initially I will be building a seperate box to house 3 damms for the 6 channels for the 3 way speakers. I am fairly convinced a RPI can run this and will testing that out as a Roon endpoint.

You can use a minidsp usbstreamer to provide 8 i2s outputs

https://www.minidsp.com/products/usb-audio-interface/usbstreamer

That's really cool. I asked Uli about it a while back and at that time there was no device that could act as a single ASIO device. Looking forward to your results!
 

Brad

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Are you aware that audiovero sells a raspberry pi based convolution device?
Uli said on the forum that it was a bit tricky to get the rasp pi to work with the chosen DAC without trouble.
SO what you want to do can be done, but depends how much of a linux expert you are.
 

DonH56

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March Audio

March Audio

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Are you aware that audiovero sells a raspberry pi based convolution device?
Uli said on the forum that it was a bit tricky to get the rasp pi to work with the chosen DAC without trouble.
SO what you want to do can be done, but depends how much of a linux expert you are.

I already use a pi as a roon end point with their roon bridge software. That works flawlessly with 2 channel. All I will do is plug the minidsp usb to i2s board into it. Already tried and it gets recognised just fine by the roon software. The convolution is done by Roon running on my nas so actually the pi doent have to do anything but talk to the minidsp board.

Uli did say that Roon had an issue with multichannel so I now need to check that out
 

hvbias

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Were you able to get this working with Acourate and the MiniDSP I2S output adapter? In one of the DIYAudio threads someone said the clocking in the Soekris DACs drifts (?) which might cause an issue here.
 
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