Help Eliminating the "thump" you get on powered speakers


Joined Nov 21, 2011
Bountyhunter, that circuit is straight forwards and will do the job..the only thing is, an up grade of the relay with 10amp contact ratings will suit the amplifier that butterworth is having trouble with in regards to on/off timer.

Thread Starter


Joined May 6, 2009
Here's a working circuit I used to eliminate the turn-on/turn-off bumps in my headphone amplifier. You need a higher current relay for a big power amp application.
This looks good too. I Would like to use a more simplified variant if possible, I have some 1n4004's laying around, could I use those in place of the 4001's? Is the Pfet also required? How can this be further simplified?

Hello Butterworth have you checked all of the information on the eps site regarding the set up? how it works, part of the circuit connects to the ac secondary side on the power amp pcb..look at the four large diodes and where your wires from the power transformer connect to it that's where the ac sense are soldered, next connect the second part of the circuit that needs dc from the + rail of the power supply rod states use 24 volt relay with 10amp contacts..this is a straight forward circuit to build and works very well indeed I've used it in my own power amp. follow all the information on this unit. also because it's meant for 2 channel use just use one side for your amp. and leave one side not connected.
The issue I have with new circuits is having to buy all the components that I never used before, relays are new to me, so I would like to find alternative routes if possible before plunging into it head first. I made that mistake once with another project, that took months to diagnose and rebuild many variants.

if you need a ready built one try velleman kits
Might be a good idea, if I can find one in my area. ;)

butterworth.. did you see the whole circuit on esp site.. there's more useful stuff on there.
Yes I did. I have seen this site many times before and found some things useful, but I do like the input I get from this forum, this is why I am asking for their input.


Joined Sep 7, 2009
There aren't any unnecessary components. It has to work on both turn on and turn off. You can substitute 1N4004 for 1N4001. The P-FET is required but not necessarily that exact P-FET.