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Old 13th April 2007, 11:42 PM   #1
nesha is offline nesha  Serbia
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Default 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 .
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Old 14th April 2007, 12:04 AM   #2
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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.
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Old 15th April 2007, 07:35 AM   #3
nesha is offline nesha  Serbia
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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.
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Old 11th January 2008, 09:33 AM   #4
Empee is offline Empee  Netherlands
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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
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Old 12th January 2008, 10:18 AM   #5
Empee is offline Empee  Netherlands
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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 !
:-)
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File Type: jpg 12at7el34.jpg (24.0 KB, 1174 views)
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Old 12th January 2008, 10:58 AM   #6
Empee is offline Empee  Netherlands
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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

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
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File Type: gif el34se6n23p1.gif (22.3 KB, 1080 views)
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Old 14th January 2008, 09:26 PM   #7
Empee is offline Empee  Netherlands
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really nobody on a EL34 SE, driven by a ECC81 ?

can't it be done ?

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Old 14th January 2008, 10:42 PM   #8
jnb is offline jnb  Australia
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Why do you want direct coupled, to avoid the capacitors? What about C3, C4?
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Old 15th January 2008, 09:21 PM   #9
Empee is offline Empee  Netherlands
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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
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File Type: jpg ecc81el34se.jpg (26.6 KB, 871 views)
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Old 15th January 2008, 09:47 PM   #10
jnb is offline jnb  Australia
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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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