Three guesses as to what this is...

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joe-electro

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Okay my fine DIY friends.  I've been working on this project for about 3 months now, and it's time to share with the group. Does anybody want to hazard a guess as to what this beast is?

Joe

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At the risk of being facetious, it's a preamp/amplifier with 6v6 outputs and likely a 5y3 rectifier tube?
The back end is similar to an RCA design used as a monitor amp in it's '50's and '60's line of consoles but of course, it's a much newer build with modern components.
 
:D
Well, surely nobody can guess it because there's absolutely no devices that use 6386 tubes!
Considering that two 6V6 are the sidechain amp, it must be, err, microwave oven?
 
Probably way off . . . but maybe a BA-25 variant with 6V6 outs . . no 12AX7 though hmm.

 
Ding ding ding!  We have a winner! Or more than one, actually.  This is the basic Sta-Level circuit with all kinds of ridiculous options in the front end and  sidechain, and room on the board for prototyping! It has options for tube or solid state rectification on the B+ so I can see which sounds better. I can also configure it to drive the sidechain more like the Fairchild, with solid state rectifiers. A pair of 5749, 6BA6 or 6BJ6 tubes can be substituted for the 6386, and there are all kinds of things I can do with the biasing of those tubes, including negative feedback.  It was designed to be the ultimate Sta-Level prototyping platform. A beta prototype will follow soon after I determine which mods are beneficial and which aren't. But I get to keep this one in my studio! Yay!

Joe
 
Sounds pretty awesome.  I'll be interested in hearing the particulars of the SS vs tube PS on this one.
Look forward to seeing the finished piece.  Good luck.
 
Not surprising. It would be very hard to guess without knowing the tube complement, which is a dead giveaway. This is a total one-off build. The odd form factor is because I'm fitting it to an old Gates chassis I found.  The beta prototype will be far more conventional, I assure you.

Joe
 
Joe ,

Looks like you used the New production Tung Sol there, I'm impressed with these for guitar amps, but have not used them
in recording gear. Can you comment on their usefulness.

Not surprising , The LA2A uses 6Aq5's which are also used as guitar output tubes , and cross over to 6V6 equiv.
Have you thought of using the 6Aq5's instead ? they are physically smaller ( 7 pin mini ), cheaper too.

Plugging a 6V6 into a tube socket mounted PCB looks like a delicate operation. Looks like it takes a little more force than
a normal PCB can withstand.

5Y3 is plentiful but requires a 5V transformer secondary , a dual 6X4 would fix that.

Just ramblin...... I'm sure that nothing really needs changing. Nice work.

Are you makin these available later ?

Still have to get a T4B going here to send out.

Build guitar amps much ?
 
The 6V6 on a circuit board is not a problem.
RCA was doing this in the '50's and the boards were nowhere near as strong as they are today.
My console has all circuit boards and tubes with a pair of 6V6's driving the monitor amp with about 6 watts.
It was built in 1953.
 
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