Canīt find the right tube for my poweramp

[Konny]

Hey guys I need your help.

I wanna build somekind of mini-Marshall with 1-3Watts to play guitar at bedroom levels.
My problem is that I canīt find a suitable tube for the powerampsection.
Iīd prefere an E-type pentode with 1-3Watts plate dissipation.

Any suggestions which tube I could use?

Thx!
Swen

[yankeerob]

They use single-ended 6V6's in Matamp Mini-Mats and get about 2 very loud watts out of 'em

Best regards

Rob

[Chuck H]

There are a couple of miniature power pentodes that put out under under 2 watts max. So in real operation you would probably get about 2.5 watts from a pair. There are also some low power triode/pentode same bottle tubes if you can design with these. Just google "small power pentode" and write down any tube #s you see to look up the data at your favorite tube data site.

"Iīd prefere an E-type pentode with 1-3Watts plate dissipation"
By "E-type" do you mean EL34, EL84,EL86 etc? These often have other designations that do not have an E. All tubes sound different. And any ELXX will sound as different from another ELXX as it does from a 6XX. Some people are of the erroneous belief that an EL84 is like a small EL34. Nothing could be further from the truth. In fact I think 6V6s crunch a little more like EL34s than EL84s do. I'd try to find an OBTAINABLE tube that fits your needs and design the circuit based on that tubes characteristics.

FWIW 2.5 watts is going to rival the output volume of a Fender Champ (3-4watts) In the real listening world 2.5 watts is VERY close to 3.5 watts. It's about as loud as a shout. If you really want to get quiet you'll need to get down to a watt or less. Some guys have built with low or medium mu tiodes like the 12au7 in class A and AB with good results.

The only real hitch I can see in getting a big amp tone in a tiny package is that the transformers and speakers are not going to be designed as close to the amps rated output as those used in big amps. Also, as dbs rise, certain audible human perceptions bend and change. And you don't have enough volume to get acoustic interaction between the guitar and amp. I've never tried it but I'm sure you could get alot of the mojo happening anyway.

Chuck

[yankeerob]

And you don't have enough volume to get acoustic interaction between the guitar and amp. I've never tried it but I'm sure you could get alot of the mojo happening anyway.

Chuck

I think you'd be surprised at the 'acoustic interaction' you could generate with just a single 6V6 - I'm presuming you mean feedback etc. Of course it all depends on the preamp in front of it - but I've heard a single 6V6 make quite a noise!!!

[Steve Conner]

Yes, a Champ-style amp with one 6V6 or EL84 should be about as loud as someone blasting on a trumpet. That's not really bedroom volume.

I've seen other forum members use a self-split 12AU7 as a power stage, and tried it myself with good results, through either headphones or a single 12" speaker. It puts out about 0.1W before clipping.

[Enzo]

Or maybe a 6SN7?

[Konny]

A SE 6V6 is too much of power and volume!
Iīve got a champstyle-clone with 6V6 SE and it can be very loud...If I wanna go for dirtier tones thereīs no chance playing at bedroom levels.

Iīm searching for a tube with 1-3W plate dissipation so Iīll get around 1W musical power when using it single ended in class-a.
I donīt think this will be too loud for bedroom levels.

With E-type I meant tubes which are heated with 6,3V. I just forgot that this is a european nomenclature

Iīve already thought about using a lo-mu triode but I think I wonīt get the sound I want, so Iīm searching for a pentode.

Swen

[Paul P]

How about a 6EH5 pentode ? Somewhere between 1 and 3 watts.

If you google "6eh5 amplifier" you'll get a few interesting hits.

Here's a youtube of a guitar amp made from one which demonstrates
both clean and dirty sounds :

http://www.youtube.com/watch?v=OdganSsvPVk

Paul P

[Konny]

The 6EH5 has a maximum of 5.5W plate dissipation and itīs maximum anodevoltage is 180V which is relatively low.
Iīd prefere something which can at least handle 250V because the pre will run around 250V

Thx!
Swen

[Steve Conner]

I wouldn't worry about the maximum anode voltage rating too much.

Also remember that to make something "half as loud" as a Champ, you need one-tenth of the power: 0.3W. You probably won't notice the difference between a 1W amp and a 3W amp.

[greg]

Has anyone built the uTube 1 watt amp? I've been toying with building one of these for a while but haven't yet taken the plunge (primarily because I find it quite simple to get a satisfactory dirty/lead tone from my amps at low volumes using a Barber Burn Unit or a tubescreamer with the Keeley mods for more gain - but I can't say it is a tone I'd want to put to tape, necessarily).

Anyway, the uTube appears to be going for the singing sustain thing at reasonable volumes using 2) 12ax7's and a 6NS7.

Here's the link:

http://myweb.absa.co.za/g.landry/uTube.htm

Good luck,
Greg