ilovefuzz.com

I never really checked before, but are there many guitar amps that you can bypass the preamp and use a pedal/preamp instead? I know that's a pretty standard feature with a lot of bass amps. Also, that's not what efx loops are for right? Those just put your effects at the end of the preamp...?

I'm not sure about guitar amps with bypassable preamps, most guys I know that want that setup just go with a power amp.

And like you said, FX loops aren't for that either. They're useful in higher gain amps that don't do well running certain pedals (esp delay or verb) straight into the preamp cuz things get to sloppy/noisey/etc. Instead the loop adds the effects in after the preamp gain sections and just before the signal hits the power amp.

Not all loops are the same. If the loop is between everything else and the phase inverter, you're in luck--ideal power-amp input. If it's after the tone/distortion generation but before reverb and trem, that'll be okay or even preferable for some if the preamp doesn't do those things. If the loop is in the middle of the tone/eq architecture, well, no good for this use, and of dubious use in general--it's usually a really dumb design choice.

Oh, if a loop plays poorly with pedals, that's often a good sign for plugging in your own preamp into the return--it's expecting a line level back instead of pedal/instrument level, and should play well with a preamp's output.

Most loops are directly between the preamp and phase inverter. Sometimes they're labeled "preamp out" and "power amp in."

With most modern tube amps the return of the effects loop can be used as a power amp input just fine. Loads of guys use AXE FX preamps this way.

Thanks for the knowledge, friends!