That's the effects loop, buddy.
So it wouldn’t be a speaker-level attenuator but rather a preamp-level volume control like Brian Wampler shows in that one video and countless players have used on that amp.
Thanks . . . i'll see if i can find said video clip.
Yeah you can do that same trick with most any pedal that has a volume knob. I have a buddy who uses an OCD, I've seen EQ pedals used for that sort of thing. If it works it works I guess.
A dude in a band I used to be in made one that was just like the 1-knob box in Pigbacon's video but it didn't work with my OR120 because their effects loops are apparently wired completely differently from normal amps.
Yeah it’s probably worth noting that this will only work with a series effects loop. If your loop is in parallel it’s just going to cause all kinds of problems! However the HRD has a series loop...
Which is about 87.3% of all guitar amps.
Cool, so that covers 104.3% of amps, what about the others?
Yes & of the remaining 17% about half of those have both. Having a level knob for the loop is a good indicator that you might have a parallel loop...
I have both on a couple of my amps... My JCM-600 & something else I’ve got in storage, I don’t exactly remember at the moment???
Parallel loops are great for vintage effects, or really any effects that may not have a level knob themselves or can be kinda overwhelming in a series loop! This becomes much more apparent when using time based or modulation effects with amplifier distortion....
Which is about 87.3% of all guitar amps.