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PSE with 6C41C

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I'm presently designing a PSE 6C41C. It will use 220V, 140mA, a 500R primary and cathode bias with a 6GK5 driver for pure A1 operation. Power supply will be sand bridge, 100uF, 2H and 220uF.

Has anyone here had experience with this tube and could they offer any advice? Reinventing the wheel is a lot of fun but it does waste time.....

Cheers,

Hugh
 
diyAudio Senior Member
Joined 2002
Hi,

Has anyone here had experience with this tube and could they offer any advice? Reinventing the wheel is a lot of fun but it does waste time.....

Basically half a 6C33-C/6C18C...

In fact I do know of one member having built an amplifier with the 6C41Pi, Bas Horneman.

Hmmm....That tiny seven pin valve is really going to stick out next to that giant septar...:bigeyes:

BAS 6C41 SE AMP.

Cheers,;)
 
Frank,

Smaller is better....

My understanding is that the 6C33B has wandering bias; correct me if I'm wrong. Of course, this probably would not be an issue with cathode bias.

I guess I'm curious to know if the parallel tubes sound as good as a single tube; matching them ain't easy.

It seems almost no-one has built with this tube. As it happens I've spoken with Bas, who kindly came straight back to me, and with Mohan Varkey, whom I visited in Melbourne recently. But very little is known about the sound qualities vis a vis the known tubes, such as the 300B, 2A3, 211, etc.

Cheers,

Hugh
 
AKSA said:

My understanding is that the 6C33B has wandering bias; correct me if I'm wrong.

Not exactly. Normal 6C33C ('till late 70s they were 100% tested by manufacturer to fit 5% tolerance after burn-in) is OK. But nowadays 90% of 33's present on market are spoilage :(


Of course, this probably would not be an issue with cathode bias.

Makes not much sense to me. Too much power waste. Personnaly I'd use IT coupling :D


But very little is known about the sound qualities vis a vis the known tubes, such as the 300B, 2A3, 211, etc.

Nothing to compare. 6C41C is bad.
Even though I don't like much the sound of 6C33C, it's way better then 6C41C. 41's are harsh, aggressive and mean. Yes, it can be diminished by certain driver topology, but never eliminated.

Good luck!

PS. Pay your attention to 6C19P... they are the best (IMHO) among the tubes of that kind...
 
diyAudio Senior Member
Joined 2002
Hi,

Not exactly. Normal 6C33C ('till late 70s they were 100% tested by manufacturer to fit 5% tolerance after burn-in) is OK. But nowadays 90% of 33's present on market are spoilage

IMHO, that's often the case when you buy locally in the USSR. Workers seem to take home rejected tubes and sell them for a $ on the local marketplaces..

As is all too often the case, quality depends very much on where and from whom you buy the tubes from, cheap often backfires.

As for bias drift, yes, I've heard similar cowboy stories from guys that don't understand that beasts like the 6C33-C require hours and hours to settle and stabilize.
This tube was often used in OTLs by folk who just wanted to jump on the bandwagon and had little experience with biasing those tubes (and even less about the Futterman topology), hence the drift stories.

Nothing to compare. 6C41C is bad.

This is something I don't understand at all, the 6C33-C is a fabulous sounding tube when driven appropriately....The 6C41-C being half a 6C33-C should sound exactly the same.

Looking at the curves and all other electrical specs I don't see any reason whatsoever why this shouldn't be the case.

PS. Pay your attention to 6C19P... they are the best (IMHO) among the tubes of that kind...

I agree, as I've been a passionate lover of the TFK ED8000, I'm mighty glad the 6C19-C is around. Only, you just can't compare it to the big ones on the power scale and if you need power, a pair of 6C33-C or 6C41-Cs would be better than just putting a bunch of 6C19-Cs in //.

One factual problem with the 6C33-C is the heater current in conjunction with the septar socket; the connection tends to heat up to the point of carbonising/blackening. To prevent it you need to wrap the heater wire around the connecting pin a few times to provide some metallic mass so heat can be dissipated better.
(I think it was 316A who kindly passed on this tip.)

SOME DATA

IN GERMAN

or two 6C19Ï in parallel.

Powerwise only...The 6C19-C isn't half a 6AS7 though.

Cheers,;)
 
Originally posted by AKSA

My understanding is that the 6C33B has wandering bias; correct me if I'm wrong.

You simply have to give it 15 - 20min before the bias becomes stable. I feared exactly the same when starting designs with these big russian bottles - causeless. They are running absolutly reliable and, for my ears, with a perfect sound (SE with good driver stage). Just keep away from the absout maximums: 45-48W plate dissipation is enough....
Marcus
 
fdegrove said:

IMHO, that's often the case when you buy locally in the USSR. Workers seem to take home rejected tubes and sell them for a $ on the local marketplaces...

Yes, you're absolutely right. But here we can easily buy 1960's 6C33C for the same price, and average 1960's is much better than average 1990's...


As for bias drift, yes, I've heard similar cowboy stories from guys that don't understand that beasts like the 6C33-C require hours and hours to settle and stabilize.

Yes, and that's why original Svetlana requirements were to test 33's only after 200 (or was it 500?) hour burn-in.


This is something I don't understand at all, the 6C33-C is a fabulous sounding tube when driven appropriately....The 6C41-C being half a 6C33-C should sound exactly the same.

Well, 6C41C is not actually "half" of 6S33S. I'd say it's "scaled down and less rugged" 33 (see picture below).


Looking at the curves and all other electrical specs I don't see any reason whatsoever why this shouldn't be the case.

Specs are close, but not identical...

6s33_6s41.jpg
 
diyAudio Senior Member
Joined 2002
Hi,

Well, 6C41C is not actually "half" of 6S33S. I'd say it's "scaled down and less rugged" 33 (see picture below).

Fair enough but I still don't see as to why the 6C41-C would sound that much worse....
Guess we'll have to try it out.

BTW, I completely forgot but there's also a long life version of the 6C41-C coded 6C41-C-(E)B.

As it only costs slightly more, it may be worth considering.

Cheers,;)
 
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