SPDIF impedance correction

[pieter t]

Here is how the digital output interfaces of my professional Sony CDP-2700 cd player look like:

When the pulse transformer in this circuit is a 1:1 type it does not have a useful function IMO.
When it is a step-down type it is functional; a step-down type is likely because there will be a couple of volts p-p coming out of the buffer IC.

 

[SoNic_real_one]

A step-down keeps the impedance high on the buffer side, while providing the needed 75 ohm. 1:1 does just galvanic separation, "breaks" an eventual ground loop.

 

[Sergelisses]

Here is how the digital output interfaces of my professional Sony CDP-2700 cd player look like:

I don't understand the two Serial resistors 51R !!! AES/EBU outputs....

Serge

 

[Sergelisses]

This is not the best circuit but it is very simple !!

Serge

 

[SY]

I don't understand the two Serial resistors 51R !!! AES/EBU outputs....

Serge

AES3-1992 specifies 110R as the standard source/load impedance. 2x 51R + the source impedance of the driver chip gets you to 110R.