Onkyo TX-SR3100 AVR 5.1-Channel used as XLR preamp - measurements

[Hayabusa]

I case of clipping that you mentioned I'd suggest 1:21 attenuator (10k - 0.5k - 0.5k - 10k) which would provide 39VRMS / 21 = 1.85VRMS.

The 'clipping' I was talking about is not about the differential voltage but the common mode signal which in you case would +/- sqrt(2)*39/2 = 27 volts peak.
My suggestion was to make the divider asymmetric which will eliminate the common mode issue.
Halving the voltage by changing you design to 1:21 does not change the common mode signal.
You can also change you schematic by making the top 10k -> 20k and the lower 10k -> 0R.

 

[Will P]

Yes, I understand.

I did very elaborate testing pushing the AVR to extremes, with and without pin 1 lift, etc.
I never experienced clipping on the XLR receiving device side.

If what you describe is a common problem I should have seen it at least once, right?

 

[Hayabusa]

Yes, I understand.

I did very elaborate testing pushing the AVR to extremes, with and without pin 1 lift, etc.
I never experienced clipping on the XLR receiving device side.

If what you describe is a common problem I should have seen it at least once, right?

Indeed it could be something specific for the E-MU404 only..
But personally I would not take the risk having my common mode swing so much.

 

[Will P]

Yes, most likely your downstream XLR device had some specific voltage limitations, different circuitry design, grounding issue or potential difference which would cause it to behave this way.

It's possible..