Mains DC blocker advice

When I bought my power amp, I was told that it was sensitive to DC on the mains, as indeed it appears to be. A constant, lowish level (though audible) volume independent, source and cable independent 50Hz buzz is present.

So, as a technical / diy Luddite, what is the best, ideally low cost DC blocking solution, for this application ?

Thanks chaps.

Have found these to be mutually exclusive, unfortunately.

Oh, deep joy. Mid cost, perhaps ?

I bought a second hand Isol-8 Powerline Axis quite a while ago, I think it was roughly £150ish?

We could also summon @Mrs_Maureen_OPinion to see if he has something in his mains bag-o-tricks.

That’s a good shout.

So, @Mrs_Maureen_OPinion, your sage advice would be most appreciated. Hell, I might even buy summat.

Fookin’ hell, the current RRP on the Powerline Axis is 600 notes!

:open_mouth: Or, I might not !

I bought a pre made circuit board that sodders recommended years ago and spliced it into a mains cable. It worked on my amp before Graeme sorted her.

You are welcome to it if you want it as I never use it any more.

That sounds ideal Stu. I’ll pm you to sort out.


No problem.

If you are handy with a soldering iron and know what you are doing then actually they’re not very hard to construct.

But the thing is that this is the AC mains. So it really has to be done properly (proper components with proper wiring and proper connectors all in a proper box). And if you make a mistake then it really can kill you or your loved ones (includes pets) either by electric shock or by burning the house down.


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Sounds perfect.

yes the isol 8 dc blocker is rare s/h , had 3 isotek syncros which i really like but they are about 500-600 . folks seem to find they are effective but isotek stuff is hideously expensive now

There you go Mike. LC Audio board. Cable glands and all.

The dust is an extra.!

I’ll post it to you on Monday.

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Thanks Stu.

Mucho appreciated.

Or you could try rebooting it?

Totally forgot to post the bastid. Will do on the morrow.

:rofl: No worries Stu

OK, so Stu’s DC blocker arrived (thanks Stu) and does a great job of making no difference at all :frowning:

More investigation and the buzz is only there when the pre (Quad 34) is connected and is present wether the pre is turned on or not. Changing the interconnect from a really cheap one, to a flashback premium one makes a bit of difference to the volume but still quite noticeable.

Any ideas as to cause (earthing I guess, although connecting a wire chassis to chassis makes no difference) or solution ?


Ahem, I use a MCRU one for my Trilogy amps and it actually works.