Powwr output of 100w fender guitar combo

The 212R has two 8 ohm, 50W, 12 inch SD speakers in parallel, resulting in a 4 ohm total impedance. So yes, if you unplug one of them, it will deliver half the output sound power.

The only thing I don't understand is why would you want that - can't you use the volume knob to do that?

"The only thing I don't understand is why would you want that - can't you use the volume knob to do that?"

That's musicians for you -- often looking for a different sound (aka distortion).

it only sounds real good if you crank the master volume up and then the overall sound is just too loud for the stage... I really would like a power soak/attenuator to achieve this. But dunno how to build on really...see? the amp sounds crap with the master vol down low.. Am wondering, if I did detach one of the speakers would it not damage the output transformer?

NO...it loses it good fender tone if u turn it down via the master... I'm after the full belt sound only quieter...

will it not damage the output transformer?

We're talking valves/tubes ? Tubes are more concerned about high impedance than transistors (which are harmed by too low an impedance).

If you disconnect one speaker from a parallel setup you will raise the impedance. If it's a series link the impedance will be reduced by removing one speaker.

Look for a switch or link inside the amp to change impedance. If not buy a hefty 8 ohm resistor and put it in parallel with the single speaker.

Better still, visit a Fender retailer or repair shop.

No, it's a transistor amplifier. The speakers are wired in series (I think), i.e. left speaker wire's connect to right speaker then right speaker up into the amp. Am trying to make it more of a 50w output rather than 100w... your info is great... Think I'll go pull some wires off...  

It's over heating of the transformer if i do disconnect a speaker

I'll re phrase that... " It's the over heating of the output transformer am worried about if I do dis connect the left speaker...  

Well, I'm getting confused now.

Whether it's tube or transistor, you still want to maintain the same impedance -- though with transistor a higher impedance shouldn't do any harm but will merely reduce the volume.

The impedance/connection equation is a) Parallel connection halves the stated impedance of each speaker. b) Series connection doubles the stated impedance.

As I said, a hefty resistor of the correct impedance could be substituted for the disconnected speaker.

Me too. If it's a vacuum tube amp and the speakers are in parallel, disconnecting one speaker will increase the output impedance lightening the load on the amp. If there is an 8 ohm output tape use it.

Solid state amps do not generally use output transformers. A higher impedance load will simply pull less power from the amp.

If you are going to try using a resistor, something like 8 ohm at 50 watts should work. It should be a non-inductive resistor.

If this amp has a direct out from the power amp section, connect it to a smaller speaker, this is often done in studios when people want a more overdriven sound at a lower volume, or simply buy a small amp, they are as cheap as chips these days...but as someone else has said, I don't understand why you can't overdrive the power-amp from the pre-amp section ? or is it specifically speaker coloration you're after ?

PP

This resistor should be able to handle the power if bolted to a chunk of metal (maybe an old processor heat sink)
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=TMC50-8.0-ND