power switch "pops" when turned off

this might be too of a general question , but

i built a point 2point la-2a and when i flick the power switch

it gives a nice pop , not ferocious but a good enough pop. (conected to speakers )

it's wired pefectly , (as in correct conections)

just wondering what might cause pops in power switch cycles.


thanks .

Probably the RF from the arc on switch break. It gets radiated and then picked up and demodulated in the electronics. Notice how the intensity of the noise varies with the essentially random time that you elect to switch---hence what the currents/voltages are at a given instant.

This can be reduced by putting a small capacitor across the power switch; maybe about a .2 mfd / 500V or so.

Or you could skip the bad habit of switching off while recording...

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:razz:

Jakob E.

ah , very cool

ill give the .2 cap and resistor

a try ,

and perhaps look for some better power switches.


thanks

driller45

Agree with Roger---the R-C should work the best.

A better switch will probably not help.

Not an issue.
Use it as is.
Be happy.

Another answer would be to put a standby switch on your LA2a, just like they do with guitar amps.

If you look at the schematic here:

http://www.freeinfosociety.com/electronics/schematics/audio/ureila2a.htm

you'd need to insert a switch at the power transformer secondary where it connects to ground (the red/yellow lead). Even then, you'd want to bypass that switch with a small capacitor as mentioned above. This cap will "absorb" the arc that occurs when the the switch first makes contact, so it shouldn't make the popping sound if you go to standby mode before powering off.

A standby switch also allows the tube heaters to warm up before high voltage is applied to them. If nothing else this will make you tubes last longer.... :grin: