[sdiy] Rotary Switch Needed

[john mahoney]

> This is for a 2x10" speaker extension cabinet not the guts of a guitar
amplifier
> so relays won't work....

Right, there's no power for the relay.


> When I use the cabinet with my Mesa Boogie Mark IIC+, I want to flip the
switch
> to the 4ohm position (before connecting and powering up the amp)
>
> When I use the cabinet with my Peavey Classic 30, I want to flip the
switch
> to the 16 ohm position (before connecting and powering up the amp)
>
> If a suitable rotary switch isn't possible, I'll just install a terminal
strip on the
> bottom of the cabinet so that I can manually re-wire the configuration....

I don't think this can be done with a DPDT switch. Series wiring requires a
link from one speaker's negative terminal to the other speaker's positive
terminal, but this can not be hardwired because it must NOT be present when
running in parallel mode. You can't wire that link into a DP switch.

You could use a 4PDT switch, which is harder to find but they do exist.
(BTW, does it have to be a rotary switch?)


Here's how I'd wire a 4PDT switch. There are 3 rows of 4 poles to connect,
so I list them in order:

Upper row (parallel): Speaker 1 Positive AND Speaker 2 Positive, unused,
unused, Speaker 1 Negative AND Speaker 2 Negative

Lower row (serial): Speaker 1 Positive,  Speaker 1 Negative AND wired to
next pole, Speaker 2 Positive AND wired to previous pole, Speaker 2 Negative

Center row (common): Positive amplifier output, unused, unused, Negative
amplifier output

I think that'll work!
--
john