View Full Version : Upstream SPDIF

2007-03-14, 20:04
I want to take the digital out from a SB2 before the inductor and attenuation. Lookind around these forums people have taken it from
a. the resistor junction
b. the buffer - 74HCU04
c. the XILINK chip

My preference is to take it as early as possible but I'm wondering about any downside of taking the capacitor (C1 on SB2)or the buffer out of the circuit. The signal will have a short trip to a transformer and s CS8416 which can take full logic level.

I have sketched part of the circuit as I understood it here. Disclaimer, this was quick and dirty and done mainly by continuity testing so may have errors.


2007-03-15, 03:56
Since the spdif receiver you mention can handle TTL levels I suppose it would be best to omit the resistor divider network. The question then remains how to terminate the spdif output, using a 75R resistor? I checked the datasheet of the 74HCU04 but it does not mention anything about output impedance of this chip.

I do not know which is better, taking the output from the hex invertor or before the hex invertor...

I removed the inductors and used an output transformer, I did keep the capacitor to avoid saturation of the transformer by DC voltage (shouldn't occur however...).

2007-04-23, 07:13
More about this, you should read this:

good luck.