switching channels with relays questions

[Bieworm]

Hey guys

I am trying to draw a schematic for a dual channel amp. I intend to switch between clean and OD with relays.
I drew 3 scenarios for the switching and wondered which one would be best. Maybe there is another method I didn't think of, so I'd be glad to hear that too...

I'd be adding reverb too between preamp and PI, so I need to enter the PI at 1 side with both channels.
I would like to avoid pop at any cost..

thanx

[d95err]

Scenario 2 looks best. Mute switchinh is usually the most silent way to switch.

However, remove the switch at the input. It fills no function and is likely to cause noise and pops.

Just tie the input to both channels.

[Satchmoeddie]

I am getting away from mechanical relays and Vactrols now that there is a photo-transistor opto-isolator that will handle 600 Volts @ 500mA. Popping is minimal if detectable at all. A capacitor can slowly charge up illuminating the LED slowly to slowly cause that photo-transistor to conduct like a switch. There are also some 4000 series logic chips that debounce and allow for a slow controlled closure of mechanical relays. I also use MOSFETs as switches too. 100,200,350,400 600, 800, 1000 volts. Muting? If choose to use a muting circuit again try to keep the mute interval short and use capacitors to bring the full signal short to ground up a tad slower than an instantaneous mute and open it just a smidge slow too. A few tens of nano-seconds either way is just fine. 8,10 or 20 nanoseconds to mute and to unmute. Great. It seems a little bit less obvious than an abrupt mute and then the signal is right back again. Mesa Boogie has some antiquated mute  circuits in lots of their older amps. These circuits LOVED to get stuck in the mute mode too, causing the whole amp to go silent.

[shaun]

Great info on switching and muting - thanks!

[d95err]

You could use the other switch pole to add another mute point in the lead channel. Either between the first and second, or second and third stages.

That would reduce the risk of bleed from the lead into the clean channel.

[Bieworm]

You could use the other switch pole to add another mute point in the lead channel. Either between the first and second, or second and third stages.

That would reduce the risk of bleed from the lead into the clean channel.

That makes sense. This very problem occurred in my last build. I had to put a 100k resistor from plate 1 to grid 2 on the lead channel to prevent that. Admitted that build has a shared V1a for both channels ( it started out as an imperial clone)