pulling tubes for 1/2 power?

[carlsoti]

I've got a Rocket 44 12" combo amp that runs a quad of EL84's. My favorite tone out of the amp is running the rythym channel volume quite high, with the gain set low. I'd like to be able to get this tone with a bit less volume. Can I pull a pair of the power tubes, WITHOUT modification, to cut the output in half, without damaging the amp?

 

[JW123]

You pull either the inner two tubes or the outer two tubes. You will only see about a 3 db reduction in volume. Good Luck

 

[carlsoti]

Thanks for that, though I knew those bits already. I guess I should've been more direct with the question.

Is it SAFE to do that with this amp, without any other mods?
I don't want to damage the amp.

 

[PC Biz]

I did it with a DC-2. No problems at all. It had two power tubes, and I pulled one out.

 

[carlsoti]

if it helps answer the question, this amp is supposed to have the same output section as the dc-3.

 

[MarkIVwidebody]

pull 1 thru 3 and just use one tube in slot 4

 

[mikey383]

pull 1 thru 3 and just use one tube in slot 4

Umm...this isn't the correct way. In a class a/b amp, you're only getting one half of the sine wave reproduced. You need a pair of tubes, one on each side of the output tranny to correctly amplify.

As for the OP, pull either the 2 inner tubes, or the 2 outer tubes, leaving the other 2 intact.

Also, this doubles the impedance, so your 4 ohm tap now becomes 8 ohms, 8 becomes 16. Adjust appropriately. Reduce the fuse size by 1/2.

 

[MarkIVwidebody]

LOL I didn't think anyone would fall for that.....I was changing preamp tubes though and pulled an inner power tube and forgot to put it back in. I turned the amp on in Class A/tweed with just the one tube and it sounded weaker and gainless almost but no other noises and it didn't do any damage in the 30 seconds before I realized it.

 

[carlsoti]

Luckily, Mark, I know better than that. I guess my neighbors will just have to learn to deal w/ it. If the police show, I'll just rat him out for beating his GF.