Channel jumping?

[twangplank]

I have always been curious about channel jumping. I hear of people using patch chords to jump channels on bf and sf fenders to get overdrive but nobody ever knows how its done and I don't want to fry my vintage amps by doing it wrong.

How is this done and is it safe? I have a vibroverb and a sf twin if that helps

Thanks in advance because I know out of all the paople on here I will get good info

[marshman]

As long as you're simply taking a short (long works, just a lot more spaghetti layin' around) and connecting the two inputs of an amp like a Tweed Bassman or vintage series Marshall, you're really unlikly to hurt anything. Most SF & BF amps don't work that way, as the channels are out of phase, and everything sounds weak and thin. Tweed amps do, BF/SF Bassman seem to, and 4-input Marshalls.

Plug your guitar into ch1, input 1. Run a patch cord from ch 1 input 2 to channel 2 input 1. Now tweak the individual channels against/with one another to acheive desired tone.

Rock-It Science!

[twangplank]

Thanks I was wondering if it works on the bf amps. I was pretty sure the twin would'nt break up much because it wont do much when using the master volume. I guess the vibro would just like an attentuater

[marshman]

Sorry, I missed the models first time by--no, the 2 channels on those amps are out of phase (so I've read, I can't tell from looking at schematics), so while the tones produced might be useful to some extent, they'll likely be thinner and quieter than any of the other tones.

Not that it's likely to change a whole lot, but I think you can chain the two amps together...I would guess if you put the 2 amps side by side and 'jump' the vibro/verb channels together, you'd get more something, but both those amps are pretty loud, together might not be all that helpful.

There are several companies making footswitchable A/B/Y boxes that can reverse phase, which would allow you to use both channels independently AND/OR simultaneously, but that's a purchase of more than a few bucks.

[mad dog]

I try it on every amp. Won't work on the reverb BF/SF. Won't work on the lo power tweed twin. Some amps it appears to make no difference. On these two, I always jumper:

Ampeg Gemini II
Gibson GA40

[Wally]

And...to the point of the original post....'overdrive'....this is not the result of chaining the channels together. This arrangement does not cascade the gain of one channel into another. It merely adds the second channel to the mix, and generally speaking yields greater tonal complexity.
NOt all BF BAssman amps have channels in phase. The circuit has unequal numbers of gain stages in the channels and therefore the channels are out of phase with each other. the '65 circuit adds a gain stage to the Normal ch andputs the two channels in phase in that amp and all of the following 5-watt Bassman amps.

[varakeef]

Tell me this.

If the channels are out of phase (like in SF or BF Twins) is it possible to use a patch cable that has the wires soldered from another plug tip to sleeve of another (and vice versa)?