Loud pop when turning off MK-III monoblocks?

I hope that would be my last question for a bit...

When I turn off either of my rebuilt MK-III monoblocks with the power switches, I get a sharp pop/chirp through the speakers. When I turn them off from the power bar, I don't get this problem. Is there an "easy fix" for this? Thank you.

ViperZ wrote:I hope that would be my last question for a bit...

When I turn off either of my rebuilt MK-III monoblocks with the power switches, I get a sharp pop/chirp through the speakers. When I turn them off from the power bar, I don't get this problem. Is there an "easy fix" for this? Thank you.

Install a snubber cap across the switch ( a cap with a built-in series resistance).
Or, don't use the built-in, the power bar is more convenient.
Or, install a SSR ( solid state relay ) and control the relay with a small DC from preamp.

So put one of these across the power switch?
https://www.digikey.ca/product-detail/en/kemet/C981U103MZVDBA7317/399-9538-1-ND/3645209

ViperZ wrote:So put one of these across the power switch?
https://www.digikey.ca/product-detail/en/kemet/C981U103MZVDBA7317/399-9538-1-ND/3645209

That will do it - it has the proper X rating for line-to-neutral.

I am surprised ones were not supplied OEM.

Thank you both.
I would have installed the caps, but I got confused when I was rebuilding the amps. There is already a disc capacitor (the 0.02 one), and for some reason I thought that it's the same cap, which is obviously not the case. I will open both amps and put the caps in, hopefully I won't have this annoying pop after that

snubber caps should always be connected across an AC power switch, this is a photo from my SP14 preamp builds.

Thanks for this post, I had a similar issue with a annoying pop when powering off my amp. A snubber cap did exactly as described.

I still get a soft pop sometimes, but nowhere near nasty harsh chirp I used to get.

Is that a Klabunde etching in the picture?

Using an SSR instead of a mechanical switch eliminates switch noice as they make or break at zero
crossing. In addition one get a remote control possibility.

Peter W. wrote:Is that a Klabunde etching in the picture?

It's a record cover . I'll take a photo of it when I'll get home.

Assuing thats a suitably rated cap or snubber you've used

tubes4hifi wrote:snubber caps should always be connected across an AC power switch, this is a photo from my SP14 preamp builds.

What value of device or part number would you suggest for an M-125 Monoblock power switch?

the capacitor I've been using the past ten years is no longer available, so I did a fresh search, and came up with these results at Mouser . . .
https://www.mouser.com/ProductDetail/Vishay-Cera-Mite/20VLS10-R?qs=%2Fha2pyFaduhVvpzkhtAh0j%2Fcg0Vvecky3JZvYXRf%252Bdk%3D
https://www.mouser.com/ProductDetail/Vishay-BC-Components/S103M69Z5UP63K7R?qs=sGAEpiMZZMuMW9TJLBQkXp4eEQ3KTPcv0%252BSLvNIe0A4%3D
this are class X2 capacitors, intended to be placed across a AC power switch, usually rated at 0.01uF and 2000vdc, or 400vac, ceramic disc

tubes4hifi wrote:the capacitor I've been using the past ten years is no longer available, so I did a fresh search, and came up with these results at Mouser . . .
https://www.mouser.com/ProductDetail/Vishay-Cera-Mite/20VLS10-R?qs=%2Fha2pyFaduhVvpzkhtAh0j%2Fcg0Vvecky3JZvYXRf%252Bdk%3D
https://www.mouser.com/ProductDetail/Vishay-BC-Components/S103M69Z5UP63K7R?qs=sGAEpiMZZMuMW9TJLBQkXp4eEQ3KTPcv0%252BSLvNIe0A4%3D
this are class X2 capacitors, intended to be placed across a AC power switch, usually rated at 0.01uF and 2000vdc, or 400vac, ceramic disc

Thanks for the information. I found a lot of safety capacitors, but I found it very difficult to find any recommendations on suitable values. This makes it much easier.

One comment. I don't see the X2 class rating for the S103M69Z5UP63K7R capacitor, just class 2 rating. The other capacitor is clearly marked as an AC line rated capacitor, class X2.

Cheers.