Can I pull two tubes from a 1200s to half the power?

[fender_bender]

I know it can be done on a fender twin reverb. But that has solid state rectifier, the sunn 1200s has two rectifier tubes?

If I can pull two tubes what are your experiences with doing that, is it bad for the amp, transformers etc?

[bigobassman]

I've seen that done, but somewhere I remember reading that it's not good to do that.  Sorry, I don't remember the reason.   

[Isaac]

I don't see why you couldn't. I've done it with my Model T.

One thing to keep in mind is that the output impedance changes. With half as many output devices (tubes), the output impedance will be twice as high. So you should have 8 ohms connected to the 4 ohm output, or 16 ohms on the 8 ohm output.

Another thing you could try is taking out one of the rectifier tubes. You'd not notice any difference at low levels, but the tubes would be starved of current at higher levels.

I can't think of any reason that doing either or even both of those things should hurt the amp in any way, but I am not an expert. There may be a reason I'm not aware of. Attempt these at your own risk.

[loudthud]

Going by how my 69 2000S is wired, you need to pull the two on one end or the other. Unlike how Twin Reverbs are wired where you can pull the inside two or the outside two. On the Sunn the inside two are connected together (push)and the outside two (pull) are connected together.