The Workbench

3-in 3-out amp switcher: is there such a thing? If not, can it be m…

1

Three mini amps, each with its own input and speaker output.

One speaker cab.

Device has to switch my input to the amp of choice, and simultaneously switch the speaker to that amp's output.

I envision:
• an input for the guitar to the switchbox
• three jacks from the box to connect to the inputs of the three amps
• a patchpoint on the switchbox for the speaker cab
• three jacks from the box to connect the speaker outs of the three amps
• three stompswitches, each of which switches both input and output for desired amp

I've looked and can't seem to find such a thing. Lots of boxes to switch between multiple amp-speaker combos. Hard to find anything that switches the input of a speaker cab to multiple amp outputs.

Can it be done? Who can make one?

2

That kind of thing will require relays and/or FET switching, so it's beyond my simple grasp.

But if you can get me a diagram and parts list, I can build it for you while we're in gorgeous Hachland Hills.

3

I can make a sort of functional diagram - parts, I don't know. Relays, FET switching, beyond my ken. Also stomps will have to be dual-function, switching two things at once. I don't even know that such a thing is made.

It's switching the outputs of the amp to the speaker in that make it a problem, I bet.

I suppose it could have pairs of stomps so close to each other that they'd be hard not to stomp together, if that would make it any easier.

5

A DPDT (double pole, double throw) switch will switch two things at once. If you were only switching between two amps I think this would be a very simple thing - the throw on one side would switch the input signal between pole A and pole B, while the throw on the other side would switch the output between poles A & B.

You’ve complicated the issue adding the third amp. Your switching will need to be either a) like an old car radio where selecting any channel pops the other switches out, or b) switched electronically with relays, logic gates, or some other silicon wizardry.

6

And don’t forget you’re also going to need dummy loads to switch on to the amps that are not connected to the speaker.

7

Hey Proteus, I looked at the (FS version) switch that JD posted. They are handmade to order. Perhaps you could ask them to build a 3 way version for you. It's worth a try, it looks like a sound design. You would need an A-B-C switch on the front end.

8

Been thinking about this while I was taking a bath. It may not be as tough as it sounds.

Firstly I don’t think you need to switch the input. I don’t think they’ll be any noticeable signal degradation if you just feed all amps in parallel with the same signal. Even if there were I’m sure one could knock up a little passive input balancing circuit to sort that out.

So that leaves the outputs. If they were fed to dpdt switches it’s just a question of wiring them so that activating switch A turns the output of amp A from the dummy load into the speaker. Same for switches B & C. This would require two stomps; one to turn off amp A and 1 to turn on amp B (or C).

Of course, you would need a failsafe. Last thing you want is to activate an amp while another is still connected to the speaker. I did that accidentally with a Pioneer HiFi amp once - boom! So the switches would need to be wired so that turning one on turns the others off. So maybe the answer is in how the dummy load is wired. Maybe with dpdt switches it could be wired so engaging any amp automatically isolates the other two amps from the speakers.

Thinking aloud here, can you tell?

9

Or use a rotary switch and do it by hand

10

Are all three amps solid-state? It wouldn't work well with a tube amp.

11

Billy, am I in the right ballpark or talking cobblers?

12

They are all solid state.

13

Are all 3 amps capable of running 4-or-8 ohm loads on the fly without any other switching? If so an 8ohm load wired permanently across each output would take care of the dummy load. Then switching a (n 8ohm) speaker in would just reduce the load to 4ohms. So now you just need to figure out the wiring so only one amp is feeding the speaker at a time.

Or I'm talking cobblers.

16

I have a Kendrick ABC unit that I had on my board. Jer has the same difference. I would get in contact with him.

17

The deLisle looks like it has the base functionality - but I'd like it with stomps. Does look like he's the man to talk to.

The others are pricey (for my casual purposes) and/or rack-mount and not obviously foot-switchable.

All three amps will tolerate 4-16 ohms.

18

There was a box like this around about 20 years ago. I just can't remember what it was called.

Made in the U.K. I believe.

20

That's the one! It was a bit pricey at the time but it really did work. Some amp repair guys used them so that you could compare the sounds of up to three amps with one guitar at the click of a switch. I don't recall exactly but I believe that you could even daisy chain at least two of them for five amps.

This was the sales blurb at the time.

"Have you ever want to play between 2 or 3 amps at once??? Here’s a great opportunity at an affordable price. Built by Gerald Weber of Kendrick Amp fame. It’s Built like a tank and there’s no need for batteries because it comes with a line voltage cord to plug into a wall outlet. Switches between 1, 2, or 3 amps or any combination of the 3. Signal doesn’t suffer."

21

That's the one! It was a bit pricey at the time but it really did work. Some amp repair guys used them so that you could compare the sounds of up to three amps with one guitar at the click of a switch. I don't recall exactly but I believe that you could even daisy chain at least two of them for five amps.

This was the sales blurb at the time.

"Have you ever want to play between 2 or 3 amps at once??? Here’s a great opportunity at an affordable price. Built by Gerald Weber of Kendrick Amp fame. It’s Built like a tank and there’s no need for batteries because it comes with a line voltage cord to plug into a wall outlet. Switches between 1, 2, or 3 amps or any combination of the 3. Signal doesn’t suffer."

– Yavapai

I don't think this is the answer to Tim's problem. The ABC while being useful does not solve the the issue of 3 amps into one cab. The deLisle might just do that as long as we can answer for the dummy load.

Originally I bought the ABC for several reasons playing 3 amps hell yeah! But blending tweed channels..

There was a concern about feedback loops but that one never played out.

22

"I don't think this is the answer to Tim's problem."

I agree. It covers the "front end" but not the "back end."

Seems that it could be done with two devices but unless the speaker impedance requirements of the amp outputs are the same then I don't know how to account for the different loads.

Might be time to ask Tim what caused this thread to start!

23

Switching inputs is easy, although a 3-way is a lot more complicated than a 2-way. Switching speakers is trickier. Amps don't like having the speaker load removed & replaced while they're cranked. You're also switching some current, even with small amps. It's possible to do, but I don't think it's a good idea.

24

BTW, you wouldn't need to switch inputs. Just plug the guitar into all 3 and leave them live.

25

Well, the purpose is amp-switching. Like the ultimate channel-switching. Arguably a more thorough tone change than stomping a dirterdrive pedal of some sort.

Go from Fenderclean to Marshallcrunch to Voxchime on the fly. (None are an actual Fender, Marshall, or Vox.)

Why into one speaker? Small rig. Tiny 5-watt amps.

If it can't be done, it can't be done - but I'm putting a total of 225.00 in tiny amps at risk.


Register Sign in to join the conversation