Bill (TGO):
Just my $0.02.
That electronic impedance switch sounds great, but I'm wondering how it can add impedance? Unless it has real big power resistors and/or caps/chokes (i.e., an impedance network that can simulate a loudspeaker load AND dissipate the necessary power inputed to same), there's no way you're getting an 8ohm load with two 8ohm (nominal) speakers unless, as Dave suggests, you're only going to use one driver at a time. As stated before, the 4ohm and 16ohm (nominal) loads are easy to achieve with two 8ohm drivers. Conversely, you'd also need that network if you had two 16ohm drivers (like I do im my 2X12 Sultone cab, wired in parallel for an 8ohm nominal load) AND you wanted a 4ohm (nominal) load impedance.
See if you can get a link to the company that makes the switch so we can all see what it is, please. If it really is all the Cas says it is, I'd be interested in one or two for my Sultone cab(s).
FWIW, I don't know if I'd be so cavalier about using the proper output taps on the amp. There's a reason they're there and that reason is that tube amps usually use an output transformer to roughly match the load impedance to the output devices (power tubes). If you use the wrong tap, and cause excess current to flow like our fellow club member in another thread did with his Mesa (Grynchin aka Brandon), you may be looking at a melted xfmr or two, tubes, resistors, caps, and maybe part of a board. He found out the hard way that fuses don't necessarily save your amp. Personally, I'd be real careful RE: impedance matching with any tube amp when using a satellite cab or two.
As I said, just my $0.02.
Cheers,
Kevin
(Message edited by kmh364 on March 13, 2006)