Hi

I thought I'd experiment with taking Ivy out of the equation with my buff 24 board and run the output cap coupled single ended. So I have buff output +ve cap coupled to output rcas, grnd direct and -ve not connected. I have a low level hum through the speakers, same irrespective of volume. Don't get this with Ivy connected, but do have a different low level buzz audible from the tweeters.

Buff 24 balanced outputs measure 1.715v on both +ve and -ve.

I don't have access to a scope, but wondered what if anything to check? I'm assuming this is not normal.

If I could get access to a scope, what should I be checking?

Buff board is supplied by 2 placids set at 6v and 6.6v. Vref mod is also in place. Photo below of setup with ivy connected. Note that mux/volumite/toslinks are supplied by a separate bridge/cap/teddyreg now, not shown in below photo. This runs off the AC supply from one of the placids.



Cheers

James

And the answer is...?

Traced it back to the separate bridge/cap/teddyreg supplying the mux etc. So the dac is now back to as in photo. It will either be that I was using a dodgy smoothing cap that had possibly seen reverse polarity at some point in its testing life, or an issue with that bridge sharing the same AC supply as one of the single placid boards. No detriment to sound quality, so I'll test that theory at leasure ;-)