Optical->optical bypass?

[siruis815]

Okay so really dumb question. I am building a streamer and amplifier chassis using RaspberryPi, HifiBerry DAC+DSP, minidsp2x4hd and 2 ice power stereo amps.

Can I hardwire the hifiberry's optical transmitter input to the minidsp's optical receiver output to avoid having to run a fiber cable inside the chassis? I'm thinking yes.

 

[altor]

Yes, sure. But take care about the grounding (because there will be no galvanic isolation).

 

[siruis815]

Thanks. Gave it a shot. Hardest part was making sure to grab the input and ground pins. Neither connectors had part numbers, but all good in the end. Thanks!

 

[altor]

Ground pin should be easy to find.
Usually:
For Transmitter:1=GND, 2=VCC, 3=Input
For Receiver: 1=Output, 2=GND, 3=VCC

 

[TNT]

"optical transmitter input" and "optical receiver output" are really contradictory but I'm glad you made it work 🙂

and why did you call it "bypass"? It seems you want a connection. Bypass = circumvent - no?

As someone indicated, you should really have separate power units feeding each side to enjoy a galvanic separation.

//

 

[altor]

"optical transmitter input" and "optical receiver output" are really contradictory

If both are 3.3v powered (ancient devices were 5v), they both have TTL/CMOS signal levels. so I don;t understand what you mean as "contradictory". Of course receiver's output must be disconnected (of receiver itself unsoldered from PCB - I thinked that everybodu here may understand that to connect 2 outputs together is a bad idea?).
And signal from transmitter input should be connected instead.
(transmitter also can be unsoldered, but not must).

have separate power units feeding each side to enjoy a galvanic separation.

With the direct connection w/o the optical cable - there will be no isolatioin at all, because the grounds must be connected, even is the power supplier are separate.

 

[siruis815]

"optical transmitter input" and "optical receiver output" are really contradictory but I'm glad you made it work 🙂

and why did you call it "bypass"? It seems you want a connection. Bypass = circumvent - no?

As someone indicated, you should really have separate power units feeding each side to enjoy a galvanic separation.

//

Yeah, sounds funny at first since most folks don't really work with the TTL input/output. And only called it bypass since in basically took the "optocoupler" out of the equation.

No additional noise was introduced by tweeter-to-ear method 🤪

 

[TNT]

"Transmitter input" is an oximoron. A transmitter is always an output! 🙂

 

[altor]

Transmitter (TOTX) have optical signal output, but electrical signal input.
Receiver (TORX) have optical signal input, and electrical signal output.

 

[siruis815]

So what I have found is that there is a bit of crackling going on with the hardwired TTL connection that's not present when using the toslink tx/rx. Very odd.