hi guys!
I am building a dual channel preamp for a LM3886 amp. I want them to be switchable. So far I thoroughly investigated the optocoupler switching, but found that its hard to find two with exactly the same on resistance.
Aside from going the way of relays, what are other ways to do channel switching? Fets? Would an arrangement like here work while being in the audio path?
http://www.blueguitar.org/new/schem/fender/blues_jr.gif (http://www.blueguitar.org/new/schem/fender/blues_jr.gif)
Any advice/opinion is welcome.
There are a ton of ways to do it, my first choice is relays, second fets, third is opto-roaches. i have a mental block against a tube signal through a fet... not that it would matter, just a personal mental block, but I'll use them outside the audio path without hesitation. i have also replaced many fet switches in guitar amps that have gotten screwey, so that puts a bad taste in my mouth. You may want to consider solid state relays... they have the fet, led and LDR built into one convenient little IC package: http://en.wikipedia.org/wiki/Solid_state_relay (http://en.wikipedia.org/wiki/Solid_state_relay)
here is a little page on fet switching http://www.pic101.com/audiosw/index.html (http://www.pic101.com/audiosw/index.html)
what about Vactec, they should be "real" photo-resistors without FETs, but they cost alot
Alex, Bancika, thanks! Interesting suggestions!
I will look closer into the relays.