Re: Mechanical hum from transformers

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In Reply to: Mechanical hum from transformers posted by Rush Paul on March 1, 2001 at 18:15:33:

I gave up trying to resolve this problem on my M60s. One chassis
is much worse than the other, Ralph kindly sent me a new transformer
which improved things but still the mechanical noise is irritating
when there is no music. I tried all sorts of tricks such as
suitably-rated caps across the primaries. What's worse is that
the two chassis interact, running them off the same power outlet
is bad. I run them off separate outlets, separated in effect
by 20m or so of mains wiring, which improves things greatly.
It's not generally realised how brutal cap-input DC power supplies
are with the magnetics. When the diodes shut off the xfmr suddenly
has a lot of core flux with nowhere to go, and dumps it into the
primary circuit. Just connect a foot of wire to the input of a
scope and you will see clearly the spikes that result. This is not
a consequence of the rectifier type, i.e. HexFreds and the rest
do not change anything. I guess tube rectifiers are gentler simply
because they switch off over a larger voltage range, hence time.
John

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Follow Ups Full Thread

Topic - Mechanical hum from transformers - Rush Paul 18:15:33 03/01/01 (1)

Re: Mechanical hum from transformers - John Harper 02:34:28 03/02/01 (0)

Follow Ups

Re: Mechanical hum from transformers - John Harper 02:34:28 03/02/01 (0)

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