Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

Modify an A/V receiver to provide multi-channel digital pre-out
Modify an A/V receiver to provide multi-channel digital pre-out
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 10th April 2007, 02:18 AM   #1
mhakman is offline mhakman  Sweden
diyAudio Member
Join Date: Apr 2007
Default Modify an A/V receiver to provide multi-channel digital pre-out

Would it be possible to modify a commercial A/V receiver to provide multi-channel digital pre-out in addition to existing analog? Background of this question is that currently available commercial all digital pre/pros are few and very expensive. Any decent modern and “cheap” A/V receiver with analog multi-channel pre-out must have that signal in digital form somewhere, before it gets converted to analog. Then, theoretically, it should be a “simple” matter to lead this signal out. Any thoughts?
  Reply With Quote
Old 10th April 2007, 11:04 AM   #2
awpagan is offline awpagan  Australia
diyAudio Member
Join Date: Nov 2004
Location: sydney
depends on which AV your looking at.
some will be easier than others.

I have a marantz sr5200 that has 4 cs4391's that go preamp out's.
thought about it a while ago, need to look at the sm again.

Indecision makes the world gone round.
  Reply With Quote
Old 10th April 2007, 05:23 PM   #3
macboy is offline macboy  Canada
diyAudio Member
Join Date: Oct 2003
Location: Ottawa, Canada
I know for a fact that this would be possible on both of my (Sony) receivers. The DACs are off-the-shelf Burr-Brown units, and are fed with standard I2S signals. You could use the same signals to feed multiple digital transmitters (DIT4192 for example) to generate the S/PDIF digital signals. Then you need to either use analog circuits capable of driving a 75 ohm load at 2 Vpp (as per S/PDIF spec) for a coax output, or use TOSLINK transmitters for fibre optic output.

One issue you will face is that the volume control on your receiver is 99% certain to be analog, after the DACs. So the new digital outputs will be more like "line " outputs than "pre amp" outputs, i.e. fixed, full volume. You will need to implement some other form of volume control.
  Reply With Quote
Old 11th April 2007, 12:12 AM   #4
mhakman is offline mhakman  Sweden
diyAudio Member
Join Date: Apr 2007
I would be prepared to sell my current receiver and buy another if I got a “ready-to-implement” mod project for that. If I had to start from scratch and do all investigation and design then I would start with the one I own right now (a Denon). I was hoping that someone did that already (for any receiver) because it’s so obvious thing to do considering commercial prices for all-digital pre/pros – about 5 times that of an AV receiver.

Yes, it should be off-the-shelf DACs fed by I2S or alike – anything else wouldn’t be cost-effective for the vendors today. I was thinking about getting I2S out of the receiver and feeding it into small external box containing of-the-shelf S/PDIF circuits then terminated by S/PDIF coax and/or optical line drivers. Or why not AES/EBU balanced ones? Sounds pretty simple in theory but I don’t know whether I would be able to get all things right in practice – it was some time ago I did my last serious electronic project (and the world was different then).

Volume control (which is the only control I need) may be a problem if the receiver uses analog attenuation after DAC. I could adjust the level at some latter stage but that would require having a computer connected to the system at all times and perhaps couldn’t be done by an IR remote control. Using receiver’s volume control would be most “seamless”. Perhaps there is a simple way to implement digital volume control in connection with S/PDIF circuits but then IR remote may be difficult to implement.

It’s a tempting project and I personally know few other people that would appreciate this very much…

  Reply With Quote


Modify an A/V receiver to provide multi-channel digital pre-outHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
High Resolution Multi-Channel Digital Interface Brian Brown Digital Source 34 15th January 2008 07:48 PM
Multi purpose multi channel gainclone PCB: Team project - group buy rick57 Chip Amps 14 29th March 2003 06:54 PM

New To Site? Need Help?

All times are GMT. The time now is 04:44 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio