Multi amp switcher thing

[fossilshark]

Hi all, so my buddy would like to connect multiple amplifiers up to a unit hooked up to 1 cabinet and be able to quickly switch between them while keeping the amplifiers on. I agree this may not be the most practical approach but who am I to judge.

My question is: what would the best way be to load down a speaker output on a tube amp? I can obviously make it so the input becomes grounded when the amp is not being used meaning IN THEORY I could just ground the speaker out but that seems like a really sketchy way of doing it. Could I use a beefy power resistor or inductor as a load that gets switched in when the speaker is disconnected?

Any advice is greatly appreciated!

[shooter]

so my buddy would like to connect multiple amplifiers up to a unit hooked up to 1 cabinet

Any advice is greatly appreciated!

find new friends with less expectations

[pdf64]

There’s commercial units made to do exactly what your friend wants. But they can be expensive.
They’re expensive for a reason, it’s not a simple thing to do. 

A beefy resistor can be used, sure.
But any switching needs to be make before break. Inductive spikes will be be caused by momentary blips of open circuit, such as that which would result from regular break before make switching.

Consider the need for very good screening between mute circuits for amp inputs and amp outputs.

[tubenit]

I've been blessed to have great friends who are kind and courageous enough to tell me when I've had a really bad idea on something.      I've grown to appreciate them and their candor.


With respect, Tubenit

[dwinstonwood]

With all due respect, I think something like this is currently the best route to take:

https://www.kemper-amps.com/products/us/profiler-powerhead.html

[kagliostro]

Few time ago a new forumer at DIYItalia asked something similar

He has a H&K Cream Machine, a Metal Master and a Crunch Master

(http://hughesandkettnermicroamps.weebly.com)

Note that the power in this case isn't very high and the guy told he would swap from one amp to the other not during the play
(on the scheme I attached there is a label that say "Amplificatori sempre alimentati" it means with all amplifiers always ON, but, as told, the guy in a second moment told he want to act the swap not during the play)

I proposed this as a possible solution but the guy vanished and nothing was realized



The swap is acted with a rotary switch that alternate the voltage feed to the relays
(feeded in couples A1+A2 - B1+B2 - C1+C2)

A1 - B1 - C1 will be small signal relays

A2 - B2 - C2 will be High current relays that can afford the current in the speaker path

The 1M resistors at the inputs are to ground the input of the amp when disconnected

the 8ohm resistors at the output (connected by the relays contcts) are the load for each amp when not in use

the 8ohm resistor at the output female jack is there as a protection if there isn't at all a speaker connected

Franco

[dbishopbliss]

A friend of mine has a de Lisle 4x4. Let's him hot swap between 4 amps and 4 cabs as well as switch in an attenuator. He uses the attenuator with his UA Ox Box. Cool piece of gear.

[SoundmasterG]

Ted Weber used to make the Fourhead. I have the last one made. TA borrowed mine to find out the details of what Ted was doing and they now make the two head switcher.


https://www.tedweber.com/gadgets/two-head-amp-switcher/




I needed the FourHead because I made an amp for myself that has 3 heads in one cabinet. It started life as a Conn organ power amp chassis for two external speaker cabinets and one internal speaker, so 3 complete output sections. i added a preamp chassis with 3 separate preamps, but realized I was going to need a way to run all those safely into a speaker cabinet or always carry 3 cabinets with me. The FourHead works as you would think, but you do need to shunt each section to the load with a switch before switching the other to the active speaker so it isn't like switching channels in a preamp or as quick. It is robust and reliable though and I don't need to switch between amps in the middle of a song, so it is fine and meets my needs. I'm sure the two head switcher is much the same and it appears to be reasonably priced.


Greg

[Esquirefreak]

There's the Radial Headbone as well. Pricey for sure, but they work very well.

/Max

[fossilshark]

Thanks for the reality check guys I just recommended he get a commercial unit so I'm not liable for his amps blowing up