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So I'll throw out a new question to you fine folk:
I tried to convince my guitar-playing friend that he could run the Randall bass head into his 70s Ampeg combo amp if he plugged the Randall out into the Ampeg ext. speaker jack. It's my understanding that you bypass all of the actual "amplification" gadgets and go direct to the speaker.

Am I close to right on this one?
This is why I play drums.

Here's my advice:

Make it easy on yourself. Don't out-think it. Keep it simple. Follow the directions.

If you want to try to experiment, don't let me stop you. But be prepared that it could be very expensive. Not only could you damage your stuff, but you could potentially hurt yourself and your friends. So, just stand back when you flip the switch.

idiot drummer wrote:

I tried to convince my guitar-playing friend that he could run the Randall bass head into his 70s Ampeg combo amp if he plugged the Randall out into the Ampeg ext. speaker jack. It's my understanding that you bypass all of the actual "amplification" gadgets and go direct to the speaker.

This isn't a good idea. The extension speaker jack is also connected to the output transformer of the Ampeg. This is the amplification equivalent of someone shitting down your throat. No, wait--that's not right. It's more like someone... ah, nevermind. Anyway, you could attach the Randall head directly to the speaker in the Ampeg combo (using speaker cable, not instrument cable), but you don't want both amps' outputs attached to each other, which is what you descibe above.

gio wrote:

It makes sense as an innovation, since the 60s twins don't have gain pots before the power amp... I'm guessing this is a rig that allows you to tweak pre- (channel 1) and post- (channel 2) gain.

Actually, this method is not stacking the channels in series (as you're describing), it's putting them in parallel. It's like sending your signal to two different amps, though in this case they come back together in the power section. This is the case whether you use a y cable or the in/out/in set-up.

Another thing about doing this with a Twin Reverb (and some other amps) is that the two channels (normal and vibrato) are out of phase--the signal from one channel at the phase-inverter is inverted from the signal of the other. This means that instead of getting a bit more signal, you'll have cancellation at some settings of the volume controls. You still might get some different sounds that you like.

idiot drummer, you might try using a clean boost (or two in a row? maybe a super hard-on, or super duper, or whatever that insane zvex boost is that i think toomany... knows about) straight into the second amp of your original example. Assuming the solid state bass head isn't distorting much on it's own, a lot of the tone you're getting is probably from hitting the input of the second amp with a higher than expected signal voltage. tmidgett mentioned the tonal effect of the unusual load on the first amp coming into play, and he's probably right about that, too.


-Tom

idiot drummer wrote:
No, it was some crazy thing where he would run a cable from the input of channel one into the input of channel two. The higher the decibels, the more overdriven the tone. I've heard of this since, but never tried it, as I do not own a Twin.

On a twin, the two channels are out of phase, and you can actually get less volume and weird out of phasey sounds by doing this.

You won't hurt your amp, and hell, you may like the sound, but it usually doesn't make it fuller or louder.

However, on Plexis, tweed bassmen, and some bassman and bandmaster amps this can be done to great results.

Cheers,

ben adrian