A little tubbey

[Andy Le Blanc]

I've working on a little tube circuit that only requires one triode stage.
Little 7pin tubes... fun to play with.

6av6 1/2 12ax7
6ab4 1/2 12at7
6c4 1/2 12au7
6at6 1/2 6sl7

With a very simple have wave PS you get around 100v to play with,
and even a 6c4 with the most rudimentary circuit can get you a gain of up to 16.
The real beauty of the old R-C amp tables is that 5% harmonic distortion is assumed.
Should have just enough gain to play with and a nice tone color.
I'd like to try 6j5 too, but its a large octal tube, can't make the case too big.

(crappy scan)

[xtian]

INterested. Pls post moar.

[Andy Le Blanc]

It's been a while since a build, here's where it starts... flat out.

[Andy Le Blanc]

lots of holes, that's more than A hole.

[Structo]

Cool I love these builds that are off the beaten path.

I think I have some 7 pinners around here somewhere.

[Andy Le Blanc]

sparkly

[Andy Le Blanc]

bent...

I've been away from so long I forgot how, I got the work stuck in the break...

I had to take the break apart to get it out...

[Structo]

Sweet!

Do you seal that with a lacquer of some sort?

[Andy Le Blanc]

not yet I was just think'in the same thing. It's a prototype personal project so maybe not, it cold out and the spray I've got on hand is murder when flashes dry.
It'd get the misses grumpy, might have to wait till the next one in a warmer season.

[Andy Le Blanc]

Parts test fit, it starts coming together for intention.
I had some fun riggin some wheat bulbs and a 9v to light the lights.
I have DPDT foot clicker, should get a bypass and a red light green light thing goin on.
should be able to finish the circuit tomorrow, internal layout is still in conception, I have to cram two 12v PT a parts board with room for the tube.
Possible fubar's not withstanding it should be pretty easy to dress the circuit once everything is in the case.

[Andy Le Blanc]

its roughly 6x8x2... L,W,H... has to big enough the house the PT.
Pretty sure you could go way small but I rather have a real hand wired amp.

[M Fowler]

Oh no Andy not another engine turned rust bucket build

Looks great!

[darryl_h]

A couple of thoughts:

1. Using a full-wave bridge rectifier could both reduce the hum level, and avoid having a DC current in the stepup transformer - for the cost of just three more diodes.

2. The coupling between the two transformers can be improved by joining the two centre taps.

[Andy Le Blanc]

I'll hit it up before final assembly, the spray is stinky bad and the house closed up for the winter, it's a bad smell...

[Andy Le Blanc]

Well... your ab-so-toot-ly right... I'm trying to keep it stupid simple.
I mean cheesy 60's consumer electronic's simple, a bridge rectumfryer will
get me around 2x the current... and I don't really need to, 6c4 only
handle 25ma. flat out, I'll find out about the hum fur sure, might have to do just that.
see how it shakes out.