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valvemaster212
10-20-2006, 08:58 PM
I was wondering if anyone could help me with this. I have a carvin tube amp and I just bought a footswitch for it (channel select). It works fine, but when I switch to the clean channel it makes a loud popping sound (audible through speakers). I'm hoping it's not something serious. This is the only tube amp I have ever owned so I am not sure as to what could be the source of the problem. Repair shops can be expensive and I don't live in an area where there are a lot of them to choose from. If there is anyone out there that could shed some light on this for me, it would be greatly appreciated.
Lordathestrings
10-21-2006, 01:28 PM
You may be stuck with it.

Some switching systems use J-FET transistors as switching elements so that the selected channel can be turned on slowly, like rolling up the volume knob. This makes for silent switching.

Mechanical switching will simply disconnect one channel and connect the other one. Any transient voltages produced by this process will get sent through the amp, coming out the speakers as a 'click' or 'pop' sound.

A phone call or e-mail to Carvin can probably resolve what kind of switching circuit is used. If they use transistors for channel selection, there should not be any clicking. If they use relays, or mechanical switches, there will always be at least a bit of noise produced.
elklandercc
10-22-2006, 12:43 AM
I have a Carvin solidstate and I have the same problem when using the footswitch. Never happens when you use the buttons on the amp itself, but that doesn't help when your jamming or giging.
Bluesman Jack
10-22-2006, 08:34 AM
Hey Lordathestrings, would a small value cap across the switch aleviate some of this switching noise?
Lordathestrings
10-22-2006, 01:08 PM
Maybe. It depends on the circuit. FET switches usually have an RC (resistor/capacitor) circuit on the gate that turns it on over a period of a few milliseconds, preventing any sudden voltage transients. A mechanical switch can't do this, of course. The problem with putting a cap across the switch is that it may pass enough of the audio signal to be heard.