out put problems

[timwebb]

what would cause an amp to hum is it to much current,even with no music playing?

[sakis]

bad wiring , earth loops, a connection with a lap top or PC , problems inside the amp hardware related loose contacts , unisoltaed plugs , problems in the rectifier board , various forms of abuse , secondary psu issues if exist , the weather , the political party you voted last year , and your last night's meal ....

[h_a]

If the wiring scheme is ok, its usually the transformer being too close to the amp-boards.

Most DIYers build however big enclosures, so that seems to happen only rarely.

If it's the wiring scheme, you need to give more details

Have fun, Hannes

PS: Sakis, did you really had one occasion where you could hear rectifier noise from the speakers? I'm just curious as in my experience everything else is so much bigger.

[sakis]

Yes i did ....also problems like that are by far more obvious when you have to do with preamps .... so amplifiers are the same thing only gain and signal levels are nto the same

[Mooly]

Is it hum ?... 50/60 hz fundamental which is a very pure LF tone, or a much harsher 100/120 hz "buzz" with harmonics ?
That's a vital clue as to what the problem is.

[AndrewT]

Hi,
is the hum a mechanical hum from the amplifier case, or an electrical signal hum coming from the speaker cone?