OT - speaker impedance

[Nasse]

Just curious, is there replacement ouput transformers available for big Fender amps with 4,8,16 ohms taps instead of only one possible speaker impedance...If you make a clone or separate top that would be optimal choice but expensive fix if your amp is ok,

Dunno how it works but believe two 12"´s in a combo sounds better on stage anyhow, though you can get huge levels from some single 12´s. Perhaps sound radiation pattern is different, not much info in my archives.

[petemoore]

Get one of those extra heavy duty little speakers [doesn't have to be hi-fi, just able to handle the wattage] and pack it tight in a dummy cabinet.
 Most of the amps I've seen have a minimum ohm rating by where the speakers are. You compute whatever ohmage the amp will see [mono amp] with 1 or more speakers and make sure that the ohmage of the speakers is not a lower number than what the amps' rated for.
 The resistor trick I've heard changes the tone as it doesn't have, or mimic the a fluctuating load like a speaker produces when driven.

[Mike Burgundy]

Nasse wrote:

Dunno how it works but believe two 12"´s in a combo sounds better on stage anyhow, though you can get huge levels from some single 12´s. Perhaps sound radiation pattern is different, not much info in my archives.

Doubling membrane area will naturally alter the radiation pattern, but it will (speakers in parallel) result in a 3dB increase in volume, if the same power goes into the cab.
If you have a "perfect" amp that will maintain a certain voltage output regardless of the impedance it sees, you win an additional 3dB because you're cutting impedance in half (doubling the power at the same voltage input, right?).
So: a 2x12 is theoretically 6dB louder (twice as loud, but keep in mind this doesn't SOUND twice as loud, you need 10dB for that) than a 1x12.
BTW: series connection loses 3dB, so a 4x12" is just as loud as a 2x12, but it has a larger radiation pattern and therefore might still appear to sound larger.