6L6 SE Amp with 20 Watts?

[Joe Bee]

Rex, for the sake of practicallity I would suggest you parallel a couple of lower power valves. Last time I checked the 6550 only had 40W plate dissipation so you will be hard pressed to get much more than 10W single ended output from one.

Steve, you need to think MOTs. They come free, pack a lot of power and the best thing is you can easily rewind them yourself since you can have a lot of volts per turn and don't need to mess with hair-thin wire. Don't tell me that after building 100kV+ Tesla Coils you are scared of insulating a transformer for 10kV or so. OK, make sure the amp never oscillates in the 10s of kHz region or you might have serious corona problems, but how COOL would THAT look in a guitar amp? :-)
Oh and I am sure that a single 4x12" could handle the power, just install a fan in the back and load it with EV 300W speakers, you know, this "the only speaker zakk wylde uses" one.

[rexindigo]

Hi, in the meantime I found this:
http://www.ax84.com/static/corepower..._Schematic.pdf

which seems to be exactly what im looking for.

But to be honest, the thought behind my initial Post was, I have this really nice sounding EL84 SE Amp build: the Preamp i designed (guessed?) myself the Poweramp is borrowed from the P1 and the only prob with it is , i would love to have this thing a lot louder before it brakes up.

So how about two el84 in parallel, why not!

How do i calculate the parts for it? how does the specs of the OT have to be?

Or is maybe the parafeed technology the right thing, at least the OT would be at an reasonable price.

[Ampclutz]

Rex,

Here's a link to Weber's kit page... Schematic and layout available there. Or even the whole kit!

https://taweber.powweb.com/store/kits.htm

AC

[Steve Conner]

Why not use..... Two SE EL84 OTs in parallel!

Joe Bee, an audio amp made out of microwave oven transformers, hmmmm... The flip side of the volts-per-turn thing is that they leak stray flux and lots of audible hum and vibration. But I guess the wall of Zakk Wylde speakers would easily drown it out. :P

Seriously though, I might nearly have enough parts to rig up a parafeed single-ended setup with that 4-400A. I just need a large choke, and I think some guy on the TCBOUK mailing list has one from a radar power supply.

[Bruce / Mission Amps]

You could always try one of these, it's a 4-400A with 400W plate dissipation. I seem to remember London Power once made a single-ended amp with a blower-cooled 4CX250B too. Svetlana make nice triodes in the 4CX250B style finned ceramic package, and I've seen them used in audiophile amps.

Does that actual say 4-400 on it?
I have a few of them and they don't look like that.
Mine look like this:

[Satamax]

Looks like with a litle missmatch Weber WSE25 trany could be used for SE6550, thought 40 dols, while the other pair goes for 90 usualy, which means 45 dols, i'd try a higher end one at 45

[Mark Hammer]

Does anybody here remember the very lengthy and often contentious thread several years back concerning the THD Univalve and how much wattage it could really produce?

Of course the irony is that differences between 10W and 15W or even between 10 and 20W are likely to not be that audible given the usual relationship between wattage and perceived changes in loudness.

[Satamax]

Does anybody here remember the very lengthy and often contentious thread several years back concerning the THD Univalve and how much wattage it could really produce?

Of course the irony is that differences between 10W and 15W or even between 10 and 20W are likely to not be that audible given the usual relationship between wattage and perceived changes in loudness.

Can't realy, but you might be able to find it?

http://archive.ampage.org/

[rexindigo]

well 45$ is not so expensive, but to be honest i never bought anything via ebay outside germany, so i dont know what shipping etc would cost and how long You would wait ?
Max, You live in France: did You ever bid in the US, what are taxes etc?

[Satamax]

well 45$ is not so expensive, but to be honest i never bought anything via ebay outside germany, so i dont know what shipping etc would cost and how long You would wait ?
Max, You live in France: did You ever bid in the US, what are taxes etc?

Hi Rexdingo.

Well, i just bought a nailer there. Two other ones in spring, a transformer etc. If you keep the price under 100 euros, you don't get caught for taxes usualy. Or you ask the seller to state it as "no declared value". Shipping wise, under 20 pounds, USPS Priority mail flate rate box is the cheapest at 37 dols.

Usps is usualy the cheapest. But if you're in germany, DHL is verry good too. I was saying 45 dols each trany plus shipping. I 'm bit short on cash and don't want to offer to do a group buy between us right now, but may be a bit later. Let me sleep on this.

Bye.

Max.

[Old Tele man]

...maximum theoretical efficiency for Class A is 50%, but practical efficiency is only about 25-30% for beam tetrodes and pentodes (triodes are less).

...however, "parallel" SE Class-A (visualize 'one-side' of 4 x 6L6 push-pull Twin, etc.) would achieve 2 x 30% of 30W or about 18W with two 6L6GC's.

[Satamax]

...maximum theoretical efficiency for Class A is 50%, but practical efficiency is only about 25-30% for beam tetrodes and pentodes (triodes are less).

Hi Old tele man.

Thta's non distorted efficiency, or only with acceptable distortion? Not guitar levels? Or that's definite physical limit and the other 70-75% are heat and other byproducts losses?

[rexindigo]

HI satamax,
yesterday i said to myself: "stop posting, start soldering" and added a octal socket to my SE EL84 Amp parallel to the EL84. (like in the very first P1 of ax84)
and although i cold not test it in the middle off the night it seemed to be a lot louder with the 6L6. i will try it in rehersal on friday, maybe i dont have even to buy hardware to achieve my goal.....

[Steve Conner]

IIRC, the maximum theoretical undistorted efficiency for SE Class-A is 12.5%.

Bruce, it doesn't have any markings, and it also has a graphite plate. I think it might be a 4-400C, and maybe Amperex or one of the Eastern European brands. I bought it from a guy who pulled it out of an induction furnace that he was scrapping.

[Joe Bee]

Somebody might want to try building an amp with this tube
http://cgi.ebay.com/ws/eBayISAPI.dll...m=270191489314
it's a GU-81, a Russian 750W pentode, so even with 12,5% efficiency you would get plenty of output.

It would definitely be worth using a push pull output transformer for this with a constant current source attached to the other tap. A gapped transformer with this power rating would probably weight a ton.