Hi I just want to make sure I use my power amp right I understand that the 2 90 2 has to have a load on both channels at all times at least I think that’s what I’m reading . But is it ok to use an A / B Both switcher . Example can I can I use chanel A and chanel b with a different preamp going into a and another preamp going into b on an A/B both switcher then into chanel a and chanel b of the 2 90 2 . And switch from a only then chanel b only then both ? You know like how a/b both box works without hurting the 2 90 2 ? Thanks again I hope I didn’t confuse this too much . Thanks for all your help
Hi Rick,
So in your setup you are using the 2/90/2 as two separate mono power amps, if I understand correctly? Your guitar signal is going to an A/B switcher and it’s two outputs are going to the A and B channel of the 2/90/2.
What is loading the 2/90/2? Two separate speakers cabs? If so that is fine! You can damage the 2/90/2 without using a load.
Regards
Dan
Yes just like a normal a/b switcher . Id like to set it up so the I have one preamp on a another on b on the switcher then run a to channel a on the 2 90 2 and b to channel b on the 2 90 2 and switch back and forth and both and yes load a and b out puts to two separate cabs. I had another question also . Is this how using mono works ? If I use channel a input only and use channel a and channel b outputs to separate cabs that will use just input channel a and drive both outputs channel a and chanel b into separate cabs ?. And for one input and one output use just channel a input again but this time leave chanel b on standby and I’ll have one channel a input and one channel a output and no channel B output ? But if I use only channel a input only and don’t leave channel b on standby it will use both outputs to septate cabs . And the same using channel a input only but have channel b on standby and I’ll have one channel a input and one channel a output ? Is this correct ? Lol sorry about this is that correct or no ? Also do I never use chanel b input only ? Or is there a use for chanel b input only ? Sorry about this and thank you very much
Thanks for all the help and any more ! It’s so hard to find well recommended guys in the past few years in my area the good ones are either too far or too busy or unfortunately retired or about to retire . I wish I lived out there just so I could I could bring my power amp or power station or any other fryette gear in to your shop for service . Like you guys said it’s new and I shouldn’t have to worry about the biasing for a while but after everything I’ve read I’m afraid to let anyone except you guys touch it . I love my 2 90 2 it’s a permanent and best part of my rig . Thanks again for everything maybe when it does become time to get new tubes and have it biased I can call you guys to find someone or possibly pay you guys to do it . And just hope it doesn’t get messed up in shipping . You guys rock thanks for making this gear 
thank you very much Richard DiCesare
Yes, you got it.
Yes, channel A input is special: it sends its input signal to channel B when B does not have an input.
Yes, that’s it.
Yep that’s the special A/Mono feature in action.
I think you said this one already? Yes.
No problem, it’s really not that much of a deal. Either ship it to Fryette, or ask any reputable amp tech to get in touch with Fryette and we will send them the information they need. You won’t be left high and dry.
Ok wow thanks for answering all that I just wanted to make sure I understood everything . Thank you very much for all the time and help .