What do you mean? Why are you taking your tubes out? Are you putting new ones in, pulling two power tubes for more power tube distortion? Why are you taking them out and what are you trying to achieve?
Oh. You were reading the DSL thread about that?
It's simple. If you have a 100W amp with 4 tubes you can normally take out half the power valves and turn it into a 50W amp. That's it. Nothing mystical. Half the power tubes, half the power, therefore more power amp distortion at the same volumes. You still have to crank it though.
You have to change the impedance setting on the amp too.
Now not all amps are the same, but most 4 power tube A/B amps will do it. I think some Mesas may be an exception, they do wierd stuff, but most others will work.
What amp are you thinking of trying it on?
Gilchrist custom
Yamaha SBG500
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100

Cathbard Amplification
My band
Last edited by Cathbard at Feb 15, 2012,
It really depends on what amp you own. Not every amp can do it.

As well, it won't make the amp much quieter, but it will reduce the headroom (make your clean channel distort more).
Quote by DeathByDestroyr
What the hell is a G&L.

Quote by Flux'D
Gay & Lesbian I think, the box smelled funny
Greg what did you send me??
Tubes work in pairs. If you have 4 tubes @100w and want to drop the amp down to 2 tubes @50w, you need to take out either the two outside tubes like I--I or the two inside tubes like

You also need to change the impedance to that speaker cab, usually when going from 100w to 50w, you need to cut the impedance in half - so lets say you are running @ 8ohms on 100w, you need to go down to 4ohms on 50w and so on.
Quote by strat0blaster
This is terrible advice. Even worse than the useless dry, sarcastic comment I made.

Quote by Cathbard
I'm too old for the Jim Morrison look now. When I was gigging I had a fine arse.
Everyone else has pretty much covered all you need to know. The only complications come when you are already running a cab at 4ohms, which just involves rewiring your cab. The main thing to worry about is pulling one set of tubes and not half of both sets, which was covered by stonyman65. Make sure you either get the outside pair of tubes or inside pair of tubes. If your amp only has 2 power tubes, you're SOL, but you've already got your amp at the power rating that's trying to be achieved, so you have no need to pull tubes.

It's for this reason that I have always preferred amps that have a half-power switch. It's just less of a pain in the ass to just flip my standby switch in the other direction if I want only 60w

I personally think they should just put a half power switch on every amp that can actually have one.