I am looking for a preamp circuit to use my JJ EL84 tube !! Please help !

[Angelo777]

Hello everyone,

Here I am again with more ideas

hehe.... I found a J&J EL84 tube i had and never got the chance in using it 

So i am thinking of building a preamp ( yes yes i know thats hard cause EL84 are meant for final amplification stage )! But we all know that it could work .... so ... any ideas in circuits ? schematics ? ... ermmm ... links ... ?

THANK YOU ALL IN ADVANCE!!!!! 

Cheers!
Angelo777

[station]

http://music-electronics-forum.com/t2032/

Looks like you can connect pins 9 and 7 and use the tube as a triode. I assume you could then use it like a preamp gain stage if you connect it the same way.

[gtudoran]

hello Angello... you could use that for preamp but it's like shooting a duck with an elephant rifle. Use the el84 for a SE power amp stage  for a 5w or so, and buy a preamp tube . You need a lot of input signal to drive that tube.

Best regards,
Gabriel Tudoran
Analog Sound

[GibsonGM]

Like gt just said, to overdrive that baby, you'd need a MAJOR guitar signal. You'd not be able to operate it as a pentode (which it is), so you'd lose all of its characteristics.  Not worth the work. 
You should just get 3 or 4 12AX7's (most popular preamp tube in the world, and the one to have if you only get 1!), a couple 12AU7s (better for lower voltages), maybe a 12AY7 for doing preamp experiments.   Could even mess around with EF86 small signal pentodes, they are great in preamps!

[petemoore]

  You need a lot of input signal to drive that tube.
  The data sheet, indespensible read for any tube application.
  A tube isn't hard to wire up, the tube itself is relatively inexpensive.
  The power supply and chassis layout can be the ''endless brick wall'' part: grounding, expensive transformers, the dangers involved with working around @HVDC as well as AC input power.
  For starters, studying the RCA tube manual [anything else] and/or a kit is recommended, starting without a known working schematic isn't.

[Ben N]

Better off using it to build a single-ended amp. Another application: reverb driver--check some old Traynor schematics for EL84-driven reverb.

[mac]

ax84.com

mac

[Angelo777]

Hello everyone,

And WOOOWWW !!! Thats a lot of answers!!! 

Gabriel Tudoran wrote:

hello Angello... you could use that for preamp but it's like shooting a duck with an elephant rifle. Use the el84 for a SE power amp stage  for a 5w or so, and buy a preamp tube . You need a lot of input signal to drive that tube.

When you say a lot of input.... do you believe that 20 db would be enough ?

Thanks a lot,
Angelo777

[Angelo777]

station wrote:

http://music-electronics-forum.com/t2032/

Looks like you can connect pins 9 and 7 and use the tube as a triode. I assume you could then use it like a preamp gain stage if you connect it the same way.

Thanks for the tip mate...   

mac wrote:

ax84.com

Thanks mate i appreciate! 

Ben N wrote:

Better off using it to build a single-ended amp. Another application: reverb driver--check some old Traynor schematics for EL84-driven reverb.

Thanks Ben i'll check it out....

petemoore wrote:

You need a lot of input signal to drive that tube.
  The data sheet, indespensible read for any tube application.
  A tube isn't hard to wire up, the tube itself is relatively inexpensive.
  The power supply and chassis layout can be the ''endless brick wall'' part: grounding, expensive transformers, the dangers involved with working around @HVDC as well as AC input power.
  For starters, studying the RCA tube manual [anything else] and/or a kit is recommended, starting without a known working schematic isn't.

Hmmm.... yeah i get your point and thanks for the advice too. The good thing is that i have a friend of mine who is an inventor and also builts transformers of all kinds and he will help me with that one ... the case will be expensive though i am considering builting one myself with aluminium.... to keep the costs down. But you know this all idea to use JJ EL84 was because i love the sound of this tube.... its so thick and "METAL" hahaha !!!

Thanks a lot!

GibsonGM wrote:

Like gt just said, to overdrive that baby, you'd need a MAJOR guitar signal. You'd not be able to operate it as a pentode (which it is), so you'd lose all of its characteristics.  Not worth the work. 
You should just get 3 or 4 12AX7's (most popular preamp tube in the world, and the one to have if you only get 1!), a couple 12AU7s (better for lower voltages), maybe a 12AY7 for doing preamp experiments.   Could even mess around with EF86 small signal pentodes, they are great in preamps!

Mate, are those EF86 thick and "heavy metal" sounded as the EL86 ?

Thanks you all in advance !!!
Best Regards,
Angelo777