Getting my cab running at 8 ohms with one or both 16 Ohm speakers

SunDevil

Here's what I'm thinking, but neither of my Physics or Electronics PhDs have turned up in the post yet, so this might not be the great idea it sounds like:

• 212 cab
• Jack 1 wired to both 16 Ohm speakers in parallel
• Jack 2 wired to No 2 16 Ohm speaker and a 16 ohm wire wound resistor wired in parallel and attached to one of the metal carry handles of the cab to act as a heat syc
• A 3P2T switch which engages both speakers to Jack 1 in the first position and speaker 2 and the dummy load in position 2

I'm guessing this is no better or worse that building a straight dummy load to run in parallel with the cab and that there should be enough air in their to manage the energy converted to heat?

Baz

ICBM

Unless you're putting a ridiculous amount of power into it, yes. Use an aluminium-cased resistor of at least the same rating as the other speaker and bolt it to the handle and it should be fine.

You will find it difficult to get a 16-ohm resistor, but 15 ohm, 18 ohm or even 22 ohm will be close enough - bearing in mind a real speaker has a variable impedance which is mostly higher than the nominal rating.

You don't need such complicated switching either, a SPDT which engages either the resistor or the speaker is enough. You only need to switch one connection to each. No need to do anything with the jacks.

SunDevil

Ah, yes - that makes sense

May well give that a whirl - thanks as ever

Baz

thermionic

Be careful when you pack up at the end of a gig, the handle might be hot!