Rewiring Amp For More Power

[AcousticSmash]

anyone know if you can rewire a amp to make it louder. I read that Jimmy Page had a 100 watt amp rewired to 200 watts but how he did it is a mystery to me. anyone know if its possible to rewire a 15 watt to a 30 watt amp without ripping it all to shreds and ruining the amp.

[silvertonessuckbutigotone]

this is my theory, I'm posting this so a more knowledgable person can verify/prove wrong my theory.

I bet if you duplicated the power amp stage of it and wired one right after another it would double the volume/wattage but I dunno if you would need to alter the preamp stage.

[lovekraft]

anyone know if its possible to rewire a 15 watt to a 30 watt amp without ripping it all to shreds and ruining the amp.

Not very likely - even if it were a tube amp, you'd have to add a second pair of power tubes, and that would probably entail upgrading both the power and output transformers - keep in mind that Page has a bit more money than you or I, so he can pretty much have anything he wants done. You could try replacing your speaker with something more efficient. You are aware that 30 watts is only about 6-10% louder than 15 watts, right? All other things being equal, it would take 150 watts to double the perceived volume. Edited February 24, 2005 by lovekraft

[westhemann]

best way to make it sound louder is to double your amount of speakers.

i sometimes hook my 15 watt amp to a pair of jensens.it pushes more air,so it makes it sound louder.

[unclej]

Not very likely - even if it were a tube amp, you'd have to add a second pair of power tubes, and that would probably entail upgrading both the power and output transformers

angela instruments has a "super single-ended 6v6 amp project" that does just this. it's a souped up champ or princeton using two 6v6's wired parallel single ended and two 5y3's also parrallel. supposed to be twice as loud and twice as nasty when cranked.

[MikeB]

if you took 2 power amps, and wired them in a bridge you could be capable of x4 the output.

in this mode one signal is inverted, and a plus goes to each side of the speaker and the earths are connected. you need a bridging adaptor on one amp. what this does is to invert the signal of the amp putput, which means it helps the other amp, and doesnt work against it. it pushes and pulls the speaker 2 times further in each direction.

both amps must be capable of driving loads 1/2 the impedance, ie a 8 ohm amp should be able to drive a 4 ohm.

DISCLAIMER:

Read up on this lots before attempting it, if you wire it incorrectly your amps will explode!! There is plenty of documentation on the web about this if interested i may be able to find you some old info i have somewhere.

Mike

[Fan O' Zakk]

Here's the deal:

You'll need to upgrade the power tranny, the output tranny, add twice the power tubes, increase the filtering in the power supply, and do a few other minor changes. Depending on the amp, should run from 200 bucks on up for parts. Labour'll getcha another coupla c-notes.

-FOZ

P.S. where did ya pick up that bit of fiction 'bout Page's setup?

[lovekraft]

...where did ya pick up that bit of fiction 'bout Page's setup?

Page used a Marshall SLP-1959 that was modified to use KT88 power tubes, giving him well over 200 watts.

[thedoctor]

AND those KT88s were running at 70% higher voltage because of full-wave rectification. Think Marshall made it an upgrade for a while.

[lovekraft]

Yes, there's not much point in running a quad of KT88s at the same voltages you would run a quad of EL34s. These amps were actually put into production in 1967 as the Marshall 200, or "Pig", ( Mick Ronson's favorite amp), and renamed the Major series in 1968. They were discontinued sometime around 1974. They were basically JTM100s with a heavier power supply and output transformers - in fact, the heads had to be built slighlty taller than the JTM100 heads to accomodate the huge transformers.

[thedoctor]

I hate to hijack this post but I will for just a minute. Lovecraft, does Genz use switchable full/half wave to allow you to retube without a full rebias or are all Genz "detuned" to run both tubes? None of my friends that own one will let me take one apart (until it breaks). They sure make some awsome-sounding stuff.

[lovekraft]

I have no idea - of course, cathode biased amps are much more forgiving of mismatched/higher current tubes, but I'm not at all sure that's what they're doing. And keep in mind that rebiasing is a relatively new phenomenon - for years, we just changed tubes with the next two in the box and played on. An amp that's designed conservatively should easily handle any reasonable variations in power tubes (remember the hum balance knob?) It's only when you get people abusing the absolute maximum ratings (Leo Fender and Mark "Matchless" Sampson come to mind) on amps that are going to be run near wide open all the time that it begins to become a problem. I'll see if I can find out what Genz has up their sleeve.

<EDIT> Yeah, doc, it looks like they're simply using a cathode bias on the poer tubes and running the current a little cool ( well, probably a lot) for EL34s so it doesn't toast the 6L6s. Not exactly optimal for the best sound out of EL34s IMO, but it does work.

Edited February 26, 2005 by lovekraft

[thedoctor]

I would have to say, yes it does!! Fabulous-sounding! Sorry about the misquote on the AC-112 issue. I thought you were saying SS amps couldn't benefit from tube preamps. My bad .