Balanced AES/EBU to/from optical S/PDIF

[novec]

This would work for an output circuit, right? The coax pad is from Rane's notes, and I'm just guessing it'll work to connect the TOTX177 ahead of it.

I'll use gmarsh's 74HCT86 input circuit, but I'll skip the inverting gates and tie the return wire to ground so I can feed coax S/PDIF into the same input without any extra switches.

 

[Bill Fuss]

Doesnt the transmitter require TTL level?

 

[novec]

That's what I'm not entirely certain of. The datasheet says TTL interface, with an active high voltage of 2-5V.

And just for the record, there's no requirement that optical out works when coax is connected.

 

[edwyun]

No longer made but you can still find online/ebay & relatively cheap.

Core Sound — M-Audio's CO3 Format Converter & SCMS Controller and AES-EBU, S/PDIF & AC-3 cables

 

[Bill Fuss]

At a glance it looks like it will work, but you can always change the pad scheme if it doesn't. Wiring in the transmitter before the second divider would probably work fine.

 

[novec]

That takes care of output. On second thought I'll ditch the idea of putting both coax and optical on the same input, so I'll use gmarsh's 74HCT86 circuit on the optical inputs with no more fuss.

There's an elaborate S/PDIF to AES circuit on epanorama (Bill's link):

                                           _
                  + 5 volt                | \
SPDIF out:          |                   +-|  O-+
                    _ +--4,7k-+         | |_/  |
              diode ^ |  _    |     _   |  _   |
       10 u (+)     | | | \   |    | \  | | \  |      100 n
O--+--+-||-+--------+-+-|  O--+--+-|  O-+-|  O-+-120 r-||-+----+-- 2
   |  |    |        |   |_/   |  | |_/    |_/             |    |
   |  +-||-+ 100n   _       2,2k |                       1 k   |
  75r               ^ diode   |  |     IC                 |    |   AES in
   |                |        --- |                       ---   |
  ---              ---           |       _                    220r
                                 |      | \           100 n    |
                                 +--+---|  O---+--120 r-||-+---+--- 3
 Diode = 1N914 or 1N4148            |   |_/    |           |
                                    |    _     |         1 k   +--- 1
                                    |   | \    |           |   |
    IC = 74HC04 or CMOS 4049        +---|  O---+          --- ---
                                        |_/

I think I'll take my chances and tie return to ground and run coax straight to live, instead... Don't know if it might be a good idea to put some resistors in there somewhere, though - it'll be about a meter of balanced cable between the input circuit and Lynx inputs.

edwyun: Thanks for the tip, but I'm hoping that won't be necessary...

 

[novec]

Here's the finished input circuit. I hope I've done the XOR part right...