Pulling two tubes in a 100 watt head

[jisham]

I was thinking of taking out two of the EL34s in my amp head to make it a 50 watt. I know it affects speaker ohm ratings right?

[edgar_allan_poe]

Yes, and depending on the amp, the tubes you pull will be different.

Example..some amps set their power tubes up like this...

ABBA

So in order to pull a pair, you need to pull the As or the Bs but *not* an AB.

Some amps are set up like this...

AABB

Find out which way your amp is before you pull a tube and wind up frying something.

[ArnieZ]

It does though I don't remeber whether you double it or halve it. It also depends on how the tubes are placed in the circuit. ON a Twin I beleve the outer pair and the inner pair in the quad are coupled so you have to pull the 2 outer tubes or the 2 inner tubes.

ArnieZ

[veatch]

It will reduce the output impedance in half.

[jisham]

I always thought you pull the outer two? To be honest, I don't think I wanna try this and blow up my amp (a Blackstar HD 100).

Thanks though.

[kenjones]

Send an email to the manufacturer?

[Armitage]

It doesn't make as big a difference as people expect. It's not so much a volume thing as you lose more "girth" to the bottom end. Remember, it takes ten times more power to double apparent volume.. so cutting it in half isn't much at all.

[kurtsstuff]

You cut the volume by 3Db...which is basically inaudible but what you also lose

is punch.......here's the math...if running a 16 ohm cab plug into the head at 8 ohms

8 ohms cab = head at 4 ohms

[Punkavenger]

I just tried this with my amp and it just sounded worse!

[jisham]

Thanks for the info as I was under the impression I'd be cutting a bunch of volume with no effect on tone. I'll leave the four tubes in.

[jaberwock]

Thanks for the info as I was under the impression I'd be cutting a bunch of volume with no effect on tone. I'll leave the four tubes in.

Did you ever consider using yellow jackets; using 4 EL84'S should cut your power to around 30 watts, but it will turn your amp into a very different animal.

[jisham]

Thanks for the info as I was under the impression I'd be cutting a bunch of volume with no effect on tone. I'll leave the four tubes in.

Did you ever consider using yellow jackets; using 4 EL84'S should cut your power to around 30 watts, but it will turn your amp into a very different animal.

Nah...I like the tone I'm getting now and was under the impression pulling two tubes would enhance the tone, but it doesn't appear that's the case.

[MCChris]

Nah...I like the tone I'm getting now and was under the impression pulling two tubes would enhance the tone, but it doesn't appear that's the case.

Nope, not in my experience. Same goes for pentode-to-triode operation IMO. Chokes off the amp's performance.

[Jeff R]

Same experience for me. Haven't found an amp yet that I've owned that improved by doing this. Usually just the opposite.

[JGale]

Jaye. What about one of these Weber attenuators?

https://taweber.powweb.com/weber/mass200.htm