P7 hum quietened by AV9?

maffs0

Standard Member
Hi,

a few months ago I bought a P7 and hooked it up to an AVR300 while I waited for an AV8 or AV9. The P7 has always had a hum that seems to be worse at some times of the day. It occurs even if I unplug all the connections to the AVR300 and the speakers. I'm pretty sure its something to do with the transformer and/or the electricity supply.

Anyway, I finally got an AV9 this week. And the really weird thing is that the AV9 seems to "quieten" the hum significantly to the point I can hardly hear it from my listening position. I cans till hear it when the units turn on but as soon as the AV9 fully kicks in, the hum all but disappears.

Can anyone think what is causing this? I'm not complaining at all :clap: but just wanted to make sure that it wasn't doing the AV9 any harm.

By the way for anyone wondering if an AV9 sound different from an AVR300 used as a pre-pro, the difference is astounding, even for stereo direct.

Appreciate any thoughts,

Matthew.
 

glorydad

Active Member
Hi,

a few months ago I bought a P7 and hooked it up to an AVR300 while I waited for an AV8 or AV9. The P7 has always had a hum that seems to be worse at some times of the day. It occurs even if I unplug all the connections to the AVR300 and the speakers. I'm pretty sure its something to do with the transformer and/or the electricity supply.

Anyway, I finally got an AV9 this week. And the really weird thing is that the AV9 seems to "quieten" the hum significantly to the point I can hardly hear it from my listening position. I cans till hear it when the units turn on but as soon as the AV9 fully kicks in, the hum all but disappears.

Can anyone think what is causing this? I'm not complaining at all :clap: but just wanted to make sure that it wasn't doing the AV9 any harm.

By the way for anyone wondering if an AV9 sound different from an AVR300 used as a pre-pro, the difference is astounding, even for stereo direct.

Appreciate any thoughts,

Matthew.

Hi Mathew

there is a ground lift switch on the back of the AV9. If you have a manual look at the bottom of page E10, this will tell you about its function. Don't know if this has something to do with your query, earthing has some weird effects sometimes.

Just a thought.

Andy
 

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