investigating the russian 6S6B-V tube

[RuudNL]

From all the tubes I have here, the 6S6B had the lowest noise.
(Also noise was very consistent. I measured a batch of 25 pcs. and the difference in self noise was minimal.)
I used one in my latest microphone and I must say I really like it.
Nice sound and very low noise.

 

[micaddict]

Yeah I've also read different opinions about the 5840...
You used all three, right? 5840, 6S6B and AC701?
You said the phaedrus solid state AC701 is alot better than the 5840.
What about the 6S6B? Better than the 5840?

You may want to include the 5703.
It's not unknown in the microphone world and, unlike the 5840, it's a triode to begin with. FWIW

 

[e.oelberg]

the 5703 and the 6S6B are west east cold war equivalents.

 

[micaddict]

That's what I assumed.

Thanks.

 

[ln76d]

For lower transformer ratio - 6112 in parallel could be nice solution. Very low noise tube and really pleasant sounding.

 

[e.oelberg]

6112 ?

 

[RuudNL]

Almost the same as the 6111, used in the Neumann M147. (Miniature double triode)
https://frank.pocnet.net/sheets/137/6/6112.pdf
(FWIW: I don't like the Neumann M147!)

 

[e.oelberg]

I see.

I'm a bit behind my plans today... I breadboarded most of the circuit, tomorrow I will do a few tests with the 6s6b .

 

[rmburrow]

the 5703 and the 6S6B are west east cold war equivalents.

The late Frank Capps used the 5703 (6AK4) in the CM2250 mics built in the 1950's... have two working ones here I reskinned with nickel...

 

[micaddict]

As early as that?
Interesting.

 

[ln76d]

Almost the same as the 6111, used in the Neumann M147. (Miniature double triode)
https://frank.pocnet.net/sheets/137/6/6112.pdf
(FWIW: I don't like the Neumann M147!)

Similar but not the same, in the same circuit (tried in two different) sounds better than 6111.
If you Rudolph think that M147 sounds bad due to tube used...
Except body, capsule and tube, everything else should go to junk in that mike.
Try plate follower with decent transformer and this tube running in parallel, then you should find what's wrong with m147.
Too much "silicon" sometimes is just unhealthy.

 

[RuudNL]

In fact, the M147 is (almost) the worst sounding microphone I ever heard!
And the sales price is ridiculous! (For this quality.)
As an other forum member once wrote: "if you like the sound of your telephone, buy the M147"!  ;D

 

[e.oelberg]

first measurement results with a 6.5:1 samar transformer and 1uF and 6S6B look promising, I'm going to build the mic now.
It's not a very scientific test setup, I just checked somehow the frequency response, so please don't believe the results

 

[RuudNL]

Looks very promising!

 

[e.oelberg]

funny point-to-point !

 

[RuudNL]

We won't tell it to anybody else!  ;D

 

[e.oelberg]

it's  fun to think the layout while building and with such a simple circuit it's pretty easy.

 

[e.oelberg]

I tuned in the bias by ear and ended up around 2.2k to ground  ...self bias

 

[stelin]

Got ten 6S6B-tubes in the mail today.  Let the tests begin!

Does anyone have any experience from burning in 6S6B-tubes? Does the noise level go down? For how long do they need to be burnt in? How about microphonics?

I've burnt in 15+ 5840 tubes for 48 hours, but I can't say that they changed in any way regarding noise or microphonics. 

 

[RuudNL]

From tests I did in the past, I noticed that during the first 15 minutes (or so), you can expect the most significant changes.
With some of the (NOS) tested tubes, the noise level was reduced during this time.
After a longer period I didn't notice any real changes.
So I think a full day is usually enough. (?)