DC blocking circuit & transformer hum

[chylld]

sorry to dig up such an old thread! but i have transformer hum and am planning to implement the dc blocker tonight. i intend to use 4 1n4004 (1a 400v) diodes and 4 2200uF 16v electrolytic caps in a similar manner to this, however i will parallel 2 caps to get 4400uF on each half (since i couldn't find the 3300/4700uF sizes) and i will be using 2 diodes in series in place of each one on the original diagram.

questions:
1) is this safe?
2) is there a better option to fix transformer hum? my humming problem has been narrowed down to the proximity between the transformer (toroidal type btw) and my amp circuit boards.

tia

[ThomasW]

This was split from this thread...

http://www.htguide.com/forum/showthread.php4?t=3584&page=2

Posts #49-63 discuss the blocking circuit

[impala454]

So just as a quick noobie's question: Did you run the transformer only in front of the circuit heading to your theater, or in front of the whole panel?

[ThomasW]

So just as a quick noobie's question: Did you run the transformer only in front of the circuit heading to your theater, or in front of the whole panel?

I'm not positive but it appears his questions relate not to balanced power but instead to a power amp that has problems with the power supply tranny humming.

http://www.stereo.net.au/forums/showpost.php?p=122674&postcount=29

[Kevin P]

Is the transformer itself humming, or are you getting a hum in your audio signal?

If it's the former, no circuit will fix that, you'll have to physically isolate the transformer from the chassis, or replace the transformer with a quieter one.

If you're getting a hum in your signal, that could be from a number of causes. A ground loop, poor filtering in the power supply, or even a video signal "leaking" into the audio.

[rc white]

If you want to fix the growl caused by toroidal transformers connected to mains having a d.c. level, this is a better article to look at..

http://sound.westhost.com/articles/xfmr-dc.htm

If you have hum being coupled into the circuit this will have no effect since it only deals with mechanical buzz due to core saturation.
rcw