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My current rig includes 3 "stacks", 2 of those being shown on the previous post's photo:
* the bass stack: 1 small 1x12" cabinet + 1 class D amplifier
* the modern stack: 1 vertical 2x12" cabinet + 3 amplifier heads
On another part of the room, I also have my vintage/british stack, which consists of a single 2x12" cab + 1 amplifier head. The guitar signal is split after my pedalboard and goes to both the modern and vintage stacks, so I can play either, or both at the same time if I want to.

2/

Now, there is one major problem with the modern stack: every time I want to switch to a different amplifier, I need to unplug/replug both the input signal cable (easy, as it's located on the front panel of each amp) and the speaker output cable (more annoying, as those are located on the back).

This is already bothering me, but will only get worse as I plan to purchase another amp (or maybe 2) for this stack, and another one for the vintage stack (which will then exhibit the same "problem")

3/

I started looking for existing "amp selector/switcher" products, and found quite a few:
* https://www.khe-audioelectronics.com/shop/asx-8 allows one to use up to 8 amplifiers with a single cab (only one at a time, of course)
* https://n-audio.net/two-amps-to-cabinet-switcher/ does the same, but only for 2 amplifiers

Those are only a few examples of what I found; they look really nice and useful, but damn are they expensive! Plus they have loads of built-in features a home guitarist like myself just doesn't need (e.g. MIDI control)

4/

So I eventually decided I'd just build my own amp switcher! I'll even build 2 of those:

* one for the modern stack, allowing to switch up to 5 or 6 amplifiers
* one for the vintage stack, switching only 2 amplifiers

I want to KISS (100% analog, no semiconductor except for a few diodes) as I won't be switching amps while playing -- this alone would make things wayyy more complex and require some kind of computing power.

5/

And a final constraint to spice things up a bit, I'd like to design a single project and make it "resizeable" in some way: the same set of PCBs should be usable for switching between 2, 3, 4, 5 or 6 amps (maybe more, we'll see) into a single cabinet.

Ideally one will just have to "cut" the PCBs to the appropriate size and/or populate the components needed for the chosen number of amplifiers.

Finally, this project will of course be 100% #OpenHardware, so stay tuned for more details

6/6

@awai If you're going for only switching with amps off and no smarts whatsoever.. then why PCBs at all?

Seems like you can get away with just wiring up a few jacks to a big mechanical rotary switch or something?

@martijnbraam I actually won't be switching mid-song, but not always with the amps off I'll probably even have multiple amps on, play one song with amp A, switch to amp B for the next tune, and so on... This will require muting the unused amps and avoiding ground loops, so...

Besides, there are also practical reasons for using PCBs:
1. ease of building
2. keep the guitar input signal (low power, high impedance) away from the speaker output signal (high power, very low impedance)

@awai ah didn't realize you're running the guitar signal also through it, makes sense.

So it's all relay switching then?

@martijnbraam yep, that's the idea :)

@awai switch register control then? or is that too digital already :P

At least it avoids having firmware

@martijnbraam nope, carefully designed circuit w/ a single rotary switch acting as the whole "command logic" should do the trick.

The project will likely be only resistors, diodes, relays and jack connectors.

@AlexanderVI Thanks! Those were made back when I was trying to build my own amplifiers brand, so they had to look (and sound) "professional" ;)