Pearse

Hey everyone, People have said you can pull out 2 of your tubes from a 100w head to make it a 50w. thing is i want to know is this dangerous to the amp itself or can i do this to get an earlier distortion curve from it without worry. Btw if it was safe i would do this with the master at 6 or 7 maybe higher and the pre amp 8-10 is this dangerous to the amp. ive done it at lower volumes ie 1.5 and no problem dont really want to crank it to find out. Any help well appreciated.

Adwex

No it's not harmful.
Pull the inner pair (2&3) or the outer pair (1&4), doesn't matter which.
Set the impedance on the amp for 1/2 the actual cab impedance.
Crank it.

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Pearse

Thanks il give it a go

stryker59

do you need to rebias if you do this?

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PaoloJM

It's always good practice to at least check it.
I pulled two tubes on my JCM800 and was disappointed with the results.
The volume drop isn't great and you loose some low end drive. I guess the power isn't there anymore to push the low frequencies. The one good side is the earlier break-up.
The next chance I get though I'll be putting them back (and re-biasing).
Your best bet for keeping power tube drive at lower volume is a good attenuator.

Regards,
Paul.

Pearse

Cheers for the help guys.
Pearse

stryker59

yeah i agree about the attenuator for sure...and for some reason i prefer the sound of a 100 watt amp over its 50 watt counterpart....

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speakerfritz

I can imagine it would be easy to pull the wrong 2. If the 100w amp uses 4 tubes as 2 push-pull pairs, you would want to make sure you pull a push pull pair, rather than a pair of push tubes or a pair of pull tubes.

Checking the schematic would help.