living sounds

Adapting S/PDIF input to accommodate AES/EBU
« on: December 15, 2018, 09:10:07 PM »
My DAC uses the attached input schematic for S/PDIF signals. What would be the correct resistor value(s) for AES/EBU signals? Thanks!


abbey road d enfer

Re: Adapting S/PDIF input to accommodate AES/EBU
« Reply #1 on: December 16, 2018, 10:46:45 AM »
My DAC uses the attached input schematic for S/PDIF signals. What would be the correct resistor value(s) for AES/EBU signals?
https://www.rane.com/note149.html
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

living sounds

Re: Adapting S/PDIF input to accommodate AES/EBU
« Reply #2 on: December 21, 2018, 06:41:50 PM »
Thanks, does this mean I cannot simply change resistor values here but have to add a voltage divider?

john12ax7

Re: Adapting S/PDIF input to accommodate AES/EBU
« Reply #3 on: December 21, 2018, 08:11:19 PM »
Do you know the ratio of the transformer? Probably around a 1:2 to match the impedance and also increase the spdif level.

So a pad would probably be necessary when using aes  level signals, as you wouldn't want a step up for them.

living sounds

Re: Adapting S/PDIF input to accommodate AES/EBU
« Reply #4 on: December 21, 2018, 08:57:56 PM »
Do you know the ratio of the transformer? Probably around a 1:2 to match the impedance and also increase the spdif level.

So a pad would probably be necessary when using aes  level signals, as you wouldn't want a step up for them.

I'm pretty sure the one I've got is a 1:1 transformer, since I took it out of an old converter's AES/EBU circuit. And I think the circuit drawing of my current converter calls for a 1:1 transformer as well.

I tried both professional and consumer level from the AES output (RME cards allow you to change this) and both work with the converter's input. But I'd rather have the correct circuit for AES/EBU. I was hoping to get away with using a different resistor for the 330R one.

john12ax7

Re: Adapting S/PDIF input to accommodate AES/EBU
« Reply #5 on: December 21, 2018, 09:45:16 PM »
My guess was 1:2 based on the 330, as that would give 330/4 or 82.5 load,  which is close to the 75 used in spiff.  What is down stream  impedance after the 330?

If it's really 1:1 transformer than a simple 110 ohm would probably be ok.  Or something a little larger than 110 to account for the down stream load that is in parallel.

living sounds

Re: Adapting S/PDIF input to accommodate AES/EBU
« Reply #6 on: December 23, 2018, 06:04:52 PM »
Thanks! I'll try next week and report back. Merry Christmas!

Whoops

Re: Adapting S/PDIF input to accommodate AES/EBU
« Reply #7 on: February 07, 2019, 06:42:42 PM »
AES to SPDIF



« Last Edit: February 07, 2019, 06:47:13 PM by Whoops »

Re: Adapting S/PDIF input to accommodate AES/EBU New
« Reply #8 on: March 06, 2019, 04:25:04 PM »
ETSlan PA-813


S/PDIF signal is almost identical to AES/EBU

key differences:
AES/EBU is usually Balanced vs. S/PDIF Unbalanced, some "professional" video equipment has unbalanced AES/EBU like Matrox MXO2 Rack for example but its rare, usually is Balanced.

AES/EBU impedance is 110ohms,
DMX is 120ohms
S/PDIF is 75ohms.

that can create signal reflection problems "cancelations" at some points of the cable.

AES/EBU usually is 5v, S/PDIF is 0.5v

the ETSlan.com PA-813 are a small balun "transformer" and also H-Pad -10dB.

they work well, but if you replace the ground wire with a better AWG24 from Proel or Belden would work better.

also needs a BNC to RCA adapter... the BNC connector wears and gets loose over time, needs to squeeze the gold pins closer again, if you have intermittent signal...

the other brands ive tested are Not as good, canare, neutrik, etc....

Trnansformer is the way to go...
with litz wire, or single strand very small AWG between 30 & 40.
the coil is 1cm donnut with 0.25cm ~ 0.5ccm core
very tiny donnut,
turns are also very small, like 5, less than 10.
3x resistors,
1 ground AWG24 wire,  done.
« Last Edit: March 06, 2019, 04:29:49 PM by Juanpcdiy »

 

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