Homebrew DC trap

[Esquirefreak]

Disclaimer: I hope this is not way off topic for this forum. In that case, I'm sorry.

Having messed with a whole lot of hifi equipment in buildings that have less than adequate power lines, my experiences with these has been really successfull. And it actually made an improvement to guitar amps as well.

The most drastic improvements I've seen is with amps that have toroidal transformers.

Why it works:
There's often a certain amount of DC voltage in wall voltages. Usually there's more of it in larger apartment buildings, where a lot of people is connected to the same power lines.

VDC tend to saturate the power transformer core, making it unable to provide the power we're calling for. In hifi equipment, the hum we sometimes hear is often actually produced by VDC rather than VAC, due to the core being saturated.

The caps/bridge rectos in the filter capture the VDC and lets the VAC through.

They're cheap to build and well worth a try.

/Max

[Esquirefreak]

And in practice

/Max

[Esquirefreak]

Note that in order to get the best performance, the filter should be on the hot line, rather than the return wire.

/Max

[mresistor]

Very interesting.

[brewdude]

Very interesting. 
Could there be any advantage to employing this filter on both hot and neutral leads?

[Esquirefreak]

I've thought about that too. I actually have an idea where you take an isolation transformer converting 1*220v to 2*110v and putting a filter on both lines. So at the same time as you isolate your amp from potential ground loops, you also filter away DC voltages.

/Max

[PRR]

Disclaimer: I hope this is not way off topic for this forum.

https://www.diyaudio.com/forums/

It's a thing. Opinions vary. It is much more a DIYaudio thing than here.

> filter should be on the hot line, rather than the return wire.
> any advantage to employing this filter on both hot and neutral leads?

Think about how series circuits work.