Speaker switch box wiring help

[ultrataco]

Just glanced at this topic. I believe your switch should incorporate some type of dummy load for the amp that is unloaded if they are both intended to be on during the switching process... seems to me it is hard on the power tubes or output transformer or both to be on and unloaded.

I guess I wasn't clear in my first post (edited now), but I will never have both amps turned on at the same time so I don't need a dummy load. If I wanted that I'd just buy an amp switcher instead of trying to build something. I just wanted a simple cheap amp switch for my situation and couldn't find one. It's understandable that nobody sells one due to risk of blowing an amp with improper use.

 

[Kissmyaxe1969]

Hi. I have 2 amps that I use with 1 cab. I don't like having to move the speaker cable back and forth between amps. I also don't want to pay hundreds of dollars for some load box thing that I don't need. So I decided to make a simple switch box.
I have it mostly assembled but not sure exactly how to wire it up so that's where I need your help. (I know how to solder.) And yes I know I can blow an amp with this if used incorrectly. I already run that risk if I forget to switch the cable before using an amp.
Anyway, I'm using an on-off-on switch. I want the middle jack to go to the speaker cab and the 2 on the side to come from the amps. Is this the correct way to connect everything?

Edit: I got all the parts from mojotone, and before buying I asked if they would work for what I want and mojotone said the parts "should work fine". I didn't ask about wiring though.

Edit 2: just to be clear: I will only ever have one amp turned on at a time and will only flip this switch with both amps turned off.

View attachment 110078

You should investigate de Lisle Amps, they make some amazing stuff as does Radial

 

[ultrataco]

You should investigate de Lisle Amps, they make some amazing stuff as does Radial

Yes I looked into those and they are nice, but it's not worth hundreds of dollars to me just to avoid the slight inconvenience of moving a cable.

 

[Led Hendriani]

Yes I looked into those and they are nice, but it's not worth hundreds of dollars to me just to avoid the slight inconvenience of moving a cable.

You could very simply tie the two speaker cables coming out of your amps about 6 inches back from their jacks and unplug one then plug the other in and therefore not even need a box... unless it is very hard to get to the back of the cab.... if it is then you could just use an extension speaker cable for the cab that has a female jack on it so you can access it from the front of the cab. Just run the extension under the cab....

 

[JohnH]

I saw the photo in post 1. Those jacks look like standard open switchcraft type where the sleeve connections contacts the case. In that case, the black half the switch is is veing shorted by the case and you are only switching the red leads. Plastic Cliff jacks are better.

I agree 110% about a dummy load. Even if you switch everything safely 99% of tbe time, the other 1% (once every 3 months if you switch once a day), an amp could be damaged.

Thus was my suggestion on the other recent thread, post #24

Two amps one cab. Switching box wanted

hi @mrjones2004x , Ive been puzzling out a diagram, and for what I was wanting to suggest I think it may need a switch with 4 poles. This is in order to switch both the hot and the cold output leads without every connecting the amps to each other, and also to switch in the safety resistor load...

www.marshallforum.com

 

[fitz288]

I've been thinking of doing a similar thing with 2 cabs to one of 2 amps.

Well, the parts showed up today, so here's my version.
- 6" x 3.5" plastic junction box ($10)
- 15A 4PDT switch ($10)
- 6 pack of Switchcraft jacks ($15)
Plan was to run 2 cabs (2x10's) to both jacks on 2 amps (3210 & G215)

Speakers are on the center 2 box jacks going to the center (common) row on the 4PDT switch.
Top & bottom sets of jacks go to either side of the switch.
Just a straight pass through, one side or the other, no parallel or series type of cab merger thing going on.
Plastic enclosure, so no common ground.

Tested impedance and switch functions and then added some handy labels.

Installed and functioning just fine.
I mounted the box on an L shaped bracket that just wedges between the heads.
Both solid state amps, so I'm not terrified of turning an amp on without a speaker load.
Just gotta remember to change the input cable from the pedals,