Taming 100 watts to 50 watts

[AKA Ninja]

I was having a discussion w/ my amp builder buddy last night and he brought up something I had heard and then promptly forgot; if you have a 100 watt amp, you can cut the power output in half by removing one pair of the push-pull power tubes. (So if you have 2 pairs of 2, each pair setup in push-pull, pull one pair out and you have a 50 watt amp.)

I'm thinking of doing that to my B-52 AT-100 so I don't get murdered quite so badly when playing it in the house. Any further considerations/repercussions I need to be aware of before doing this? I would just ask my buddy (I trust him lots) but he just got done modding my amp for me and I don't want to bug him and look stupid.

[Mushroony]

Yes,it works. I've done it with my 6505 once to try it. But i'll guarantee you that the difference between 50W and 100W volume-wise is almost non existing. You just cut headroom and low end. So imo, it's not worth it. But hey, give it a try, it doesn't do any harm.

[AKA Ninja]

Yes,it works. I've done it with my 6505 once to try it. But i'll guarantee you that the difference between 50W and 100W volume-wise is almost non existing. You just cut headroom and low end. So imo, it's not worth it. But hey, give it a try, it doesn't do any harm.

Yeah I realize that in order to get a noticable volume change it has to be a difference of 3x, so I'd have to drop it down to ~30 watts before a volume change is noticable. I was hoping I might get some results by cutting the output and dropping my 2x12 down to just one speaker in that configuration ... dunno. Will report if it does anything useful.

[OysterBoy]

I did that on my 100 watt tube half stack. I noticed two things about it, one is the volume doesn't change hardly and two, it sounded looser and weaker. When I put the tubes back in I sensed the "drive" behind the tone. I guess it gained headroom.

[GPW]

AK, It works as long as you pull the right tubes ...  But Dude , you just need a smaller amp  ... I'd suggest something around 18 watts , so you can crank it to the sweet spot ... mic it if it's not loud enough ... save the 100 watt for the stadium gigs ... 

 FWIW , I just finished a 2 watt "bedroom" tube amp  (6N2Pev> 6P1Pev ), and it's LOUD !!!  Louder than it needs to be in a bedroom  ...   

[AKA Ninja]

AK, It works as long as you pull the right tubes ...  But Dude , you just need a smaller amp  ... I'd suggest something around 18 watts , so you can crank it to the sweet spot ... mic it if it's not loud enough ... save the 100 watt for the stadium gigs ... 

 FWIW , I just finished a 2 watt "bedroom" tube amp  (6N2Pev> 6P1Pev ), and it's LOUD !!!  Louder than it needs to be in a bedroom  ...   

Yeah, I know, I need a smaller amp. When I bought this amp, I was ACTUALLY looking for something in the 15-22 watt range; but this jumped out at me, and you know how it is, "I MUST HAVE TO HAVE IT!!!"...

I still keep a solid state around for when I want to appease the family, but sometimes the monster just has to get turned on, and they just have to deal with it 

[SecretWeapon]

When choosing wattage and volume remember that in order to get twice the volume you actually have to multiply the wattage by 10. The human ear hears in such a way that in order for you to perceive the sound as twice as loud, it has to be ten times louder.

So a 5 watt amp is really only half as loud as a 50 watt. The difference is in the cabinet. Plug a 5 watt amp into a 4x12 cab and you're still going to piss off every neighbor on the block.

So reduce your speaker count, or get a small cab with a 10" in it.

GPW - I have a couple JRC386 based solid state amps that i've built for friends. 1/2 a watt solid state and plenty loud for bedroom practice! 

[AKA Ninja]

Yeah I know the science behind speakers/volume (see the amp faq ), I was just curious of everyone's opinion of this particular technique.

[GPW]

 SW, is that like the Ruby amps @ Runoffgroove...

AK, do Like I did ...move to the woods , build a concrete block bunker for a Studio , and Crank it up LOUD  ....   

[SecretWeapon]

SW, is that like the Ruby amps @ Runoffgroove...

These are similar to that, based off the same chip. Its really nothing too special, as with most 386 based amps its just variations on the same things for taste. I've built Ruby and Little Gem from runoffgroove as well as the "Noisy Cricket" from beavis audio and of course my own personal take on the 386 amp.

I've actually been nosing around at sub-mini tube amp projects but there aren't a lot around. I'm looking for something simple with 1-2 watts of output. It'll be my first tube project.   

Fun stuff. 

[GPW]

 SW, try the Tone per Buck Club at    http://www.wattkins.com/node/15993    We've been making small thrifty 2-3 watt amps now , got it all worked out ... pretty easy , and inexpensive ...  Latest one I built is called the Thrifty Croaker ... costs 75 bucks in materials ...  Sweet TONE too !! 

[GPW]

and a gut shot !!! 

[SecretWeapon]

GPW thats a pretty sweet looking little unit!

... But the Wattkins amp forum wont let me in... It says

Access denied
You are not authorized to access this page.

... Dang. 

[GPW]

  Join up Dude !!!   It's free and only takes a minute ...  If you like this kind of stuff , it's well worth it ..   Tell em' the Geezer sent you ... 

[Chris]

Yeah, its definitely worth joining.