Noisey Switches

[TIMBO]

I have some noisey switches in my build. SW1, SW4 and SW7 other than turning down the volume is there any other way of taking out the SNAP and Thump or should some of these not be switched while playing. I also noticed that the preasence pot was a little scratchy. Thanks

[kagliostro]

did you try to put a "large" resistor across the switch ?

Kagliostro

[FYL]

I have some noisey switches in my build. SW1, SW4 and SW7 other than turning down the volume is there any other way of taking out the SNAP and Thump or should some of these not be switched while playing. I also noticed that the preasence pot was a little scratchy.

One common cause: DC. You're switching high voltages and your presence pot is in // with the cap. Try for instance to add a large coupling cap between the plate and switch, rework your presence circuit with a serial cap. Or manipulate the switches with tha amp off or dimed...

[sluckey]

Copy the presence from one of the Marshalls that have the cap in series with the pot. Like this...

http://www.schematicheaven.com/marshallamps/jcm800_lead_50w_1987.pdf

[Shrapnel]

High resistance across each throw per pole, such as 10M should help, may be able to get away with less. It's because of the differences between voltages/signals when switched. A 10M should give electrical continuity, while providing enough resistance to any signal to keep it minimized.

Doesn't matter if it's just a plain switch, or relay activated, if it's in the signal path, try the 10M. (Outside of the signal path shouldn't make any noise.)