6/8 Channel DIY USB DAC

thomas.hood · 26th March 2006, 07:16 PM

Hello All,

Does such a thing as the subject exist. All I want is 6 or 8 channels of high quality DAC, with a good clock and linux support. I'm slightly reluctant to spend 200 quid on an maudio or similar as you seem to be spending alot of money on stuff you dont' need (mic preamps, input ADCs, SPDIF connector etc.)

Thanks for your advice,

Thomas Hood

johnthedoctor · 27th March 2006, 06:49 PM

I've been looking and haven't found much. The M-Audio Transit seems cheap enough to try modding. (Not that I know how.)

Best idea I've come up with so far is to concentrate on the front speakers and let the other 4 have 2nd/3rd best, ie. the soundcard DACs.

Something like a PC -> HagUsb -> Monica2 -> Charlize for the fronts and feed the rear, sub and centre amps from the soundcard outputs.

Anyone got an opinion an how 'vital' sound quality is for the other 4 (or 6) speakers? I'm hoping that as long as the fronts are excellent, having lesser quality DACs feeding the surrounds won't be that noticable.

rfbrw · 27th March 2006, 10:45 PM

Why USB ?

johnthedoctor · 28th March 2006, 06:47 AM

In my case the front speakers would have to be from USB as the SP/DIF output of my soundcard doubles as the sub/centre analogue out. (The vesajack on the TB Santa Cruz.)

I suppose I could upgrade it but that would divert funds from other projects and I don't see the point of a new card just to get a separate SP/DIF output.

MWP · 28th March 2006, 07:12 AM

I made one.

I modified a MAudio Revolution (aka Santcruz) sound card to have 3 optical SPDIF outputs.

I then made a 6 channel intergrated DAC + bridged Gainclone amp.

I used brutefir on the Linux box to do active xovers and room correction which then used 5 of the channels (left low & high, right low & high, sub).

All worked very well.

Getting more than 2 channels through USB requires custom ICs and drivers at the moment, so i would forget about this option unless you are going to modify someone elses hardware.

A few photos...

Modified soundcard:

One of the three DAC + Bridged gainclone amp boards:

enter · 28th March 2006, 11:42 AM

HI

Nice work you did there MWP!

I whant to ask you diy folks if this could be done with the one SP/DIF output of my sound card (x-fi)for all 6 channels?
I have never build a dac before so if there is a way for me to do this i would like the most simple way to do it

Thanks

thomas.hood · 28th March 2006, 03:58 PM

Very impressive indeed MWP.

This could do the trick for me. Was the DAC amp combo of your own design -- and if so are PCBs (or art) available?

How is volume control implemented?

Thanks,

Thomas Hood

indoubt · 28th March 2006, 04:29 PM

Quote:

Originally posted by johnthedoctor
I've been looking and haven't found much. The M-Audio Transit seems cheap enough to try modding. (Not that I know how.)

Best idea I've come up with so far is to concentrate on the front speakers and let the other 4 have 2nd/3rd best, ie. the soundcard DACs.

Something like a PC -> HagUsb -> Monica2 -> Charlize for the fronts and feed the rear, sub and centre amps from the soundcard outputs.

Anyone got an opinion an how 'vital' sound quality is for the other 4 (or 6) speakers? I'm hoping that as long as the fronts are excellent, having lesser quality DACs feeding the surrounds won't be that noticable.

Look on http://www.empiricalaudio.com/ for highly modified M-Audio transits.

I own a transit as wel but are still in the experimenting phase. (probably simple capacitor/connector/housing upgrade)

Note that the transit is not a 6/8 channel dac although it can "pass through" multichannel DTS

edit: there are measurements done of the capacitor upgrade. if of interest I could dig them out of the WWW.

MWP · 28th March 2006, 09:10 PM

Quote:

Originally posted by thomas.hood
[B]Very impressive indeed MWP.
This could do the trick for me. Was the DAC amp combo of your own design -- and if so are PCBs (or art) available?
How is volume control implemented?
[B]

Yeah, it was all my own design.
The volume control was done via a 2-step relay attenuator on the PCB, and the rest via software.

No PCBs available as i made those myself, and the schematics & PCB design files i dont really want to give out.
I did have a screen shot of the schematic somewhere, but i cont find it

26th March 2006, 07:16 PM	#1
thomas.hood diyAudio Member Join Date: Jul 2005 Location: London	6/8 Channel DIY USB DAC Hello All, Does such a thing as the subject exist. All I want is 6 or 8 channels of high quality DAC, with a good clock and linux support. I'm slightly reluctant to spend 200 quid on an maudio or similar as you seem to be spending alot of money on stuff you dont' need (mic preamps, input ADCs, SPDIF connector etc.) Thanks for your advice, Thomas Hood

28th March 2006, 11:42 AM	#6
enter diyAudio Member Join Date: Jun 2005 Location: Athens	interesting HI Nice work you did there MWP! I whant to ask you diy folks if this could be done with the one SP/DIF output of my sound card (x-fi)for all 6 channels? I have never build a dac before so if there is a way for me to do this i would like the most simple way to do it Thanks

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27th March 2006, 06:49 PM	#2
johnthedoctor diyAudio Member Join Date: Sep 2005	I've been looking and haven't found much. The M-Audio Transit seems cheap enough to try modding. (Not that I know how.) Best idea I've come up with so far is to concentrate on the front speakers and let the other 4 have 2nd/3rd best, ie. the soundcard DACs. Something like a PC -> HagUsb -> Monica2 -> Charlize for the fronts and feed the rear, sub and centre amps from the soundcard outputs. Anyone got an opinion an how 'vital' sound quality is for the other 4 (or 6) speakers? I'm hoping that as long as the fronts are excellent, having lesser quality DACs feeding the surrounds won't be that noticable.

27th March 2006, 10:45 PM	#3
rfbrw diyAudio Member Join Date: Oct 2001 Location: .	Why USB ?

28th March 2006, 06:47 AM	#4
johnthedoctor diyAudio Member Join Date: Sep 2005	In my case the front speakers would have to be from USB as the SP/DIF output of my soundcard doubles as the sub/centre analogue out. (The vesajack on the TB Santa Cruz.) I suppose I could upgrade it but that would divert funds from other projects and I don't see the point of a new card just to get a separate SP/DIF output.

28th March 2006, 07:12 AM	#5
MWP diyAudio Member Join Date: Oct 2002 Location: Adelaide, South Australia	I made one. I modified a MAudio Revolution (aka Santcruz) sound card to have 3 optical SPDIF outputs. I then made a 6 channel intergrated DAC + bridged Gainclone amp. I used brutefir on the Linux box to do active xovers and room correction which then used 5 of the channels (left low & high, right low & high, sub). All worked very well. Getting more than 2 channels through USB requires custom ICs and drivers at the moment, so i would forget about this option unless you are going to modify someone elses hardware. A few photos... Modified soundcard: One of the three DAC + Bridged gainclone amp boards:

28th March 2006, 03:58 PM	#7
thomas.hood diyAudio Member Join Date: Jul 2005 Location: London	Very impressive indeed MWP. This could do the trick for me. Was the DAC amp combo of your own design -- and if so are PCBs (or art) available? How is volume control implemented? Thanks, Thomas Hood

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