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-   -   EL34 SE, direct coupled (http://www.diyaudio.com/forums/tubes-valves/100013-el34-se-direct-coupled.html)

nesha 13th April 2007 11:42 PM

el34 se,direct coupled
 
Hi everybody.It is obvious what schematics I m looking for.Tubemaster s el84 se direct coupled and Morrison 2a3 are both interesting , but el34 and it s 5 watts are a temptation I can not ressist... but to look for.Thanks .

Eli Duttman 14th April 2007 12:04 AM

You say you like the DC coupled EL84 circuit, but want more power. EL34s are harder to drive than EL84s. OTOH, 7591s are as easy to drive as EL84s, a fact that Fisher and Scott took full advantage of.

What Fisher and Scott did, you can do too. 7591s are in production at Saratov and Jamona.

nesha 15th April 2007 07:35 AM

Thanks, I ll try to learn obout 7591 . 813 transmiting pentode is very interesting too, representing easy job for driver tube and could give 20 w in triode mode.BUT ... a good output tranies of that power are too expensive , and I don t have directcoupled schematics for it. I m newbie , so I can t calculate desired cirquit ...yet. Thanks again.

Empee 11th January 2008 09:33 AM

Hi !

Sure, EL34's are harder to drive than EL84's,
but can't it be done with two halves of a ECC81 parallel ?

I'd really like a schematic for a direct coupled EL34 SE using
ECC81 driver, but is it possible ?


Cheers,

Empee

Empee 12th January 2008 10:18 AM

2 Attachment(s)
c'mon, guys ?!

nobody on a direct coupled EL34 ?


cheers,

Empee

<edit:>

Ok, so I found this....

That cap isn't in the signal pad

(or is it? someone once told me;
"anything in there affects the signal")

but it seems direct coupled, and using 12at7 & el34

will this be any good ?


Cheers again !
:-)

Empee 12th January 2008 10:58 AM

2 Attachment(s)
OK, sorry for the above post...

I looked closer and saw my mistake;
half #1 of the 12AT7 is actually driver stage, coupled via
the cap, half #2 of the 12AT7 is for distorsion purposes...
so no good for my apllication :D

However,
I found attached shematic !

Now this IS dc-coupled but it uses a 6H23 tube, wich would be
close to an ECC88...

can this schematic be re-worked for a 12AT7 / ECC81 ?


Cheers,

Empee

Empee 14th January 2008 09:26 PM

really nobody on a EL34 SE, driven by a ECC81 ?

can't it be done ?

:confused:

jnb 14th January 2008 10:42 PM

Why do you want direct coupled, to avoid the capacitors? What about C3, C4?

Empee 15th January 2008 09:21 PM

2 Attachment(s)
Well,

not to completely avoid caps,
(I do not think it's possible)
but surely to minimize their effect by reducing their number...

So far I only found one schematic using an 12at7/ecc81,
but this one isn't DC coupled...

still a nice schematic, I think


Cheers,

Empee

jnb 15th January 2008 09:47 PM

I think being able to use smaller caps is good because they can be film and not electrolytic. Your latest schematic looks better in this one regard.


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