March 26th, 2012, 11:29 AM
I have a standby switch in my 5E3. Sometimes there is a pop sound when engaging the standby switch. Not surprising since you are taking away/adding B+ into the circuit instantaneously, and I'm assuming that popping noise is the big filter caps charging/discharging.
I've noticed that Weber has a capacitor from one side of the standby switch wired to ground in their high powered tweeds (not present in their 5E3 layout)...is this there to prevent popping?
March 26th, 2012, 12:14 PM
You are half correct, the pop is due to the fact that you are breaking a high voltage DC connection. But it is not the sound of the capacitors discharging, they continue to hold their charge just fine.
A standby by switch is entirely unnecessary in a 5e3. If you want to leave the amp on, but kill the volume then just use the volume knobs, and if you want to turn the amp completely off there is no need to switch to standby - just turn the power off (that goes for any amp with a standby.)
March 26th, 2012, 12:59 PM
I'm aware that a standby switch isn't necessary in the 5E3. That is besides the point...I like to use it to kill the amp quickly and have it come right back online without fiddling with the control settings. It's a personal preference.
Also, I've observed the same popping phenomenon in a little homebrew amp I have that switches in different cathode bias capacitors on a preamp tube. When you flip the switch, you instantaneously throw in another capacitor that was disconnected from the circuit, and there is a pop because the cap is charging up. Quickly throwing the switch back and forth doesn't cause a pop, because the caps haven't completely discharged yet.
Same thing happens with the standby in my 5E3...quickly flipping the switch back and forth doesn't cause a pop. It's only when the amp has been on standby for a while (i.e., the filter caps have nearly completely discharged) does the pop occur.
Taking away B+ from the filter caps is the same as turning off the amp from the cap's perspective. The caps will start to discharge right away.