Is it possible to take the signal before optical for a coaxial digital connection? - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

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 25th September 2013, 10:46 AM   #1
Nazo is offline Nazo  United States
diyAudio Member
Join Date: Nov 2010
Location: Alabama
Default Is it possible to take the signal before optical for a coaxial digital connection?

So I'm thinking of building a project where I would have a cheap USB DAC connected to a Fiio D3 to act as the actual DAC with a CMoy handling the analog stage. While it may be no substitute for the $200+ DAC+amps out there, it's pretty darned good in my initial tests. One piece of inelegance is very annoying though: connecting the USB DAC to the D3. Running a huge optical cable from one to the other and then having to switch them back and forth (or using a Y-splitter) isn't just ugly and messy, but it actually gets in the way and makes the whole package bigger and less portable.

I'm wondering: is it possible at all that the digital signal going to the optical converter is basically the same as what is used with coaxial connectors? Or, if not, could it be something simple like adding a resistor or capacitor or other such thing? If I could just run a couple of wires from it to the D3's coaxial input, I could have it completely internalized. It might be bad to have both the USB DAC and something else connected to that input at the same time, but I can't foresee having the USB connected AND an active coaxial connection at the same time.

Is it possible, or are they two very different things in this case?

I've attached a picture of the PCB from the USB DAC in case it helps determine anything. I circled the three pins that I believe go to the optical section of the TRS connector.
Attached Images
File Type: jpg SD-AUD20101-highlight.jpg (265.9 KB, 67 views)
  Reply With Quote
Old 26th September 2013, 11:06 AM   #2
atupi is offline atupi  Romania
diyAudio Member
Join Date: Oct 2010
Location: Bucharest
My Egreat media player has only optical digital output and i obtained a spdif connection installing a RCA connector between GND and Signal of optical connector. Works very well for me. I have already a coupling cap on my DAC spdif input.
You can follow same way for your situation and it should work.

  Reply With Quote
Old 27th September 2013, 06:02 AM   #3
Nazo is offline Nazo  United States
diyAudio Member
Join Date: Nov 2010
Location: Alabama
Ok, after a LOT of digging around and confusion since I've never done anything remotely like this I managed to find a data sheet for the VT1620A and figure out which pin of the three is the signal. In fact, it explicitly states "SPDIFO" for pin 28 in the datasheet. After following the trace, failing, and using a multimeter and a magnifier and a very very steady hand, I managed to identify connector 3 (the bottom one) as being the SPDIF signal and soldered in a connector with RCA on the other end. After not so bravely forcing myself to flip the switch, it worked. No smoke, just clear clean audio.

Thanks. I am curious, is there any danger if there were two SPDIF signals connected at once to either the USB DAC or the D3? I seriously doubt I'll ever have both at once, but I'd like to at least hear that the whole thing won't go up in flames if I did accidentally do it...
  Reply With Quote


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
How to convert optical to coaxial digital output? marchel Digital Line Level 4 24th June 2010 12:33 PM
optical coaxial connection mhtplsh Solid State 1 17th May 2008 01:16 AM
FS: Digital Signal Converter- Optical in Coax Out akunec Swap Meet 0 16th May 2007 07:04 AM
Problem: intermittent optical digital signal dropout? faustian bargin Digital Source 0 6th April 2004 09:21 PM
Circuit to convert coax digital signal to optical? bobo box Digital Source 17 9th March 2004 11:01 PM

New To Site? Need Help?

All times are GMT. The time now is 10:42 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.
Copyright 1999-2016 diyAudio

Content Relevant URLs by vBSEO 3.3.2