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Torroidal transformer hum and DC Blocker DIY

Posted by HumanMedia (A) on March 7, 2009 at 18:37:57

OK I have a bad hum on two components torroidal transformers, and have long known that its probably DC on the main supply. Apart from the physical hum I'm told that humming transformers probably affect the audio quality as well, so it should be a very worthwhile tweak.

I know about the commercial products available that block DC on the mains AC including the CIAudio XDC (I have CIAudio amps so this might make a good combo).

Anyway I started planning to DIY a new power strip then thought that I should build this in as it probably wont be much extra work and at least I can control the quality of the components inside (and save money).

Since I'm an electrics noob I thought I would post my plans here for peer review, for any guidance to make sure Im not doing anything that might detriment the sound and to get feedback on how to make it better. Im also thinking that others might want to know all of this as well.

We have probably all seen this DIY DC blocker:
http://diyparadise.com/dablok.html

Which was superceded by the discussion here:
http://www.diyaudio.com/forums/showthread/t-104626.html

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

To end up with the circuit diagram from Ellliot Sound Products (shown above) also linked at:
http://sound.westhost.com/articles/xfmr-dc-f8.gif
(ignore the transformer to the right)

My pick of components for 240V use:
2 x 15000uf/25V Polar caps (647-UFW1E153MRD)
4 x 10A600V Diodes (512-FFPF10UP60STU)

Maybe Im going overkill on the diodes, and maybe I should have gone with the 33,000uf/6.3V as Bryston use with the DC blocker in their amps, especially since the DIY discussion tapers off with a preference for lower voltage and higher capacitance.

Any comments, opinions or guidance?

Edits: 03/07/09 03/07/09 03/07/09 03/07/09

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