Tiny Amplifiers

[soundbrigade]

I have my to-do-list (see below) which I try to clear little by little. Last year was not a good year as I lost too much of initiative and drive and energy. Finally I ended up in total apathy - couldn't start new projects, nor finish old ones.

Well I am on the move again and after having finished the 6AQ5-PP, found that it was fun building small amps with big sounds, so I have started to look for small projects and ask you for help and inspiration.

In another tread I digged up two amps that could be smallish:
amp86 and Amp87.
Ger Reinhöfer has made a VERY tiny thing with Russian miniature tubes -
ZWERG .
I'd prefer a PP-amp as I will get more power and I think at least that the OP-transformer would end up smaller than a comparable SE.










(*) Stealth (12A6PP)
(*) 2A3SE
(*) EL84 STC PP
(*) Finish my TB-speakers. Waiting for some paint now.
(*) 832PP
(*) 829SE - halted
(*) 12B4A lineamp possible with an inductive potentiometer
(*) The MONSTRET (8W transistor from Audiophil)
(*) Soundlab synth
(*) Active crossover
(*) Bench PSU for valves.
(*) Maybe 50CA10PP
(*) CG-preamp
(*) Something "dangerous" - a GM72, Bautapentode: 22W SE.
(*) 807-SE STC
(*) Microamp with tubes

[Jaap]

found this somewhere

[soundbrigade]

Snagged!

Looked interesting, will check for the coupling transformers.

[Jaap]

It is of course not tiny with all those transformers because they need to have some distance to each other I suppose and it will weigh something too. I wonder of this design can be stretced to a karna-type (Lyn Olson).
Real tiny amps can of course be made with ecl82or ecl86.
See also: http://www2u.biglobe.ne.jp/~hu_amp/6bm8a_e.htm

[soundbrigade]

Oh, I've built the STC, crammed it into a 10" x 6" x 2" Hammond box. Sad that SE-transformers get big.
One way to get pass this size-problem is to build a Matrix amp:
Darling Matrix

[Jaap]

sometimes smaller is better

[soundbrigade]

If small is better, I don't know but they say less is more ....

I just wonder - could it be possible to use a 100V line transformed AC-coupled to a totem-poled pair???

[Jaap]

Is STC sounding good ?
I am thinking of building this one (in a small hammond box)

[soundbrigade]

I built the 6BM8-STC but used a penthode as input/CS.

I am about to build exactly the 6BQ5/EL84-amp you are considering. Have all parts at home but have a few other projects going on.
For the 6BQ5 PP STC I have a mainstransformer from Lundahl but its look is awful and must be hidden somehow.

I also consider an 807 STC.

[soundbrigade]

Going through my files and folders I came up with some more serious (mor or less) candidates for small stuff:

A SE amp based on a single 6080: 6080SE
Simple SE/PP-amp using crafty dual triodes: Dual triode PP/SE
A PP-amp (guess it has been shown already): EL84 PP STC
Two amps (maybe identical?) on 50EH5: Single tube 50EH5 SE and second