Reducing speaker thump on a Solid State amp

ZenOvertone

Calling the amp experts -  can I reduce the speaker switch on/off "thump" in a tranny amp by changing or increasing the value of the filter caps, I think the better answer is a timed relay circuit to connect the speaker but that's impractical.  It's just a small Fender in the living room but would be good to quieten this down :-)

Sassafras

I get that on a Tech 21 amp. Let's me know that everything's working.
'Tis annoying though.

ecc83

Fit a switch in the speaker circuit and switch speaker on a few seconds after the amp. Probably good as well to fit a 1k resistor across the speaker jack to allow the output cap to charge if there is one but handy for a DC coupled amp anyway.

Dave.

pintspiller

Or turn volume down before you switch off and up again after you switch it on next.

 8-)

shrinkwrap

You can fit a mains rated capacitor across the mains terminals on the power inlet.

X-rated cap 400 V 10nF - I did it and it stopped a Marshall practice amp going thump, but don't come to me if you screw this up. I'll happily remove this if ICBM or someone else advises it's a crap solution. I don't have the amp any more either.

ecc83

shrinkwrap said:

You can fit a mains rated capacitor across the mains terminals on the power inlet.

X-rated cap 400 V 10nF - I did it and it stopped a Marshall practice amp going thump, but don't come to me if you screw this up. I'll happily remove this if ICBM or someone else advises it's a crap solution. I don't have the amp any more either.

I would not be happy with anyone who has to ask advice here doing ANYTHING around mains circuits. In any case, after such work the amp would need a PAT test, certainly before it was sold.

This is a solid state amp anyway and the thump is caused by the settling of the voltages in the output transistors and really the only way to fix it is to NOT have a speaker connected for the few seconds it take the power stage to sort itself out.

Dave.

Whistler

Many solid state amps have a headphone output which silences the speaker. Plug in a stereo headphone adaptor while you switch on and then remove it, that will achieve what exx83 and others have said without mnodifying your combo.

https://thumbs.static-thomann.de/thumb/thumb150x150/pics/prod/165014.jpg

ecc83

Whistler said:

Many solid state amps have a headphone output which silences the speaker. Plug in a stereo headphone adaptor while you switch on and then remove it, that will achieve what exx83 and others have said without mnodifying your combo.

https://thumbs.static-thomann.de/thumb/thumb150x150/pics/prod/165014.jpg

It will, good idea but, if you have such an amplifier and especially if it is of 10W or greater power, check the PCB around the headphone jack from time to time. Jack switches are not rated for several amps of AC, can get hot, cook print and cause dry solder joints.

Dave.