ZenV2 Hum

[Shoog]

My zen Vol2 sounds great but it has a slight hum problem. When you switch on and for about a hour or so afterwards there is no hum, then slowly the hum creeps in till its noticable from the other side of the room.
I have a big 24V toroidal followed by bridge, 10,000uf of cap, a cap multiplier and finally two x 22,000uf of cap. The two channels work off the same supply. The power supply is unshielded (apart from a sheet of lead over it), and sits between the two channels.
I have a hunch that it is the transformer warming up and starting to hum more. Also the caps are top quality slavaged.
Any ideas !!!!

Shoog

[Nelson Pass]

Is it mechanical hum from the transformer?

[Shoog]

No sorry, i'am talking about hum from my high efficiency speakers.

Shoog

[Panelhead]

Originally posted by Shoog
No sorry, i'am talking about hum from my high efficiency speakers.

Shoog

Shoog,
I suspect you have a grounding issue. I built mine with a 10K cap, 2.7 mH choke, and 10K cap. My transformer is a 300 watt 38 volt Plintron, and it and the two chokes are inbetween the circuit boards. I was concerned about radiated hum.
But it is dead quiet. On my Lowthers (100 db) speakers you cannot tell if the amp is on. I put output switches because I was worried about turn on and off thumps. But it was quiet on power up and down to boot.
The grounding really does not explain the warm up effects, but I am listening to an Aleph X that hums a little. It is worse for the first 20 - 30 minutes and then the hum level decreases. I have no idea why.

George