pre-outs to SuperUniti from AV receiver - hum problems. Any tips?

Posted by: JedT on 10 July 2017

Music is by far my priority but when we largely rebuilt our house I did install surround speakers in the ceiling and drive those plus a centre speaker and sub from a (pretty humble) Denon AV receiver taking preouts for front L/R into my SU. I've never been able to escape an annoying hum on the L/R channels when the SU is in AV mode.

I do use quite a long run of interconnect but I've experiment using a short interconnect and it didn't fix the problem. I've played around with powering the AV and SU from different power sockets (SU/180/phonostage/turntable are all powered from a hydra type mains set up). No joy.

Any bright ideas?

Posted on: 10 July 2017 by james n

You have a Ground loop. I take it there is no hum on the main system with the AV receiver disconnected from the SU ?

You'll need a ground isolator between the AV receiver and SU like this below to break the ground connection between the two.

Posted on: 10 July 2017 by JedT

Ah, assumed it was a ground loop or something but wasn't aware of that piece of kit. Thanks.

And yes no hum apart from via the avr (and have tried connecting the AVR) to alternative inputs.

Thanks again

Posted on: 18 July 2017 by JedT

Just to say that the ground isolator did the trick. Thanks James.

Posted on: 18 July 2017 by james n

No worries - glad you got the problem sorted