multi-tap speaker jack wiring

[Randall]

Is it possible to reliably use the 4 and 8 ohm taps with two speaker jacks that will automatically switch between:

8 ohm cab into 8 ohm jack, or
4 ohm cab into 4 ohm jack, or
two 8 ohm cabs into both jacks

If not, what would be the preferred switching method?

Thank you!

[Tom Phillips]

On method that does not require a separate switch is to install two jacks wired in parallel connected to the 4 Ohm tap. Then you just know how that you can plug in two 8 Ohm loads to those jacks if it's your amp or you mark the panel so that others will have a chance of figuring it out.

[Randall]

I can see how you can get two 8 ohm or one 4 ohm with this method Tom, but what about one 8 ohm speaker?

[g1]

A third jack would be wired to the 8 ohm tap, for use with a single 8 ohm cab.
I like Tom's idea of using 3 jacks so no switch is required. But that would be the other option, 2 jacks and a switch to choose the 4 ohm or 8 ohm tap.

[Randall]

YES! Thank you Tom and g-one. Three jacks, no switch, perfect. I knew I was making it more difficult than it needed to be. Thank you guys!

[Tom Phillips]

Yep. Three jacks. I meant to state that but upon re-reading my post I find that I just thought it but didn't make it clear in the text.
Cheers,
Tom

[pdf64]

As I see it, an impedance selector switch only becomes beneficial (over the arrangement Tom describes) when there are 3 options required.
eg 5 jack sockets to accommodate 4,8,16 as either single cabs or parallel pairs of 2x8 or 2x16.
Pete

[bobshbob1]

You can also do this with 2 jacks and no switch: the 8-ohm jack is a standard open-circuit jack, and the 4-ohm jack is a transfer-type. (like this)

Wire it up so the tips of both jacks are connected together, and connect both 4- and 8-ohm taps from the OT to the 4-ohm transfer jack, the 8-ohm to the normally-closed connection and the 4-ohm to the normally-open connection.

Then when nothing is plugged into the 4-ohm jack, the 8-ohm tap is engaged and you can plug into the 8-ohm jack no problem. When you plug something into the 4-ohm jack, the 4-ohm tap is engaged, so you can use one 4-ohm or two 8-ohm cabs and only be using the 4-ohm tap on the OT.

This is how they do it on my Peavey Butcher. It's pretty idiot-proof, but I'm personally not a fan of having switching jacks for speaker connections...up to you though, just my 2 cents.

[Randall]

I would avoid switching jacks as well. Sooner or later, they will be a problem.