EL34 SE, direct coupled - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 15th January 2008, 10:46 PM   #11
G is offline G  United States
diyAudio Member
 
G's Avatar
 
Join Date: Apr 2002
Location: Belleville, IL.
This is a schematic of my current amplifier. You will have to play around with the biasing of the EL34, increase the current, to get the maximum power out of them. The TFA 204 transformers that I used saturate at 60mA. I don't think I have ever seen a DC coupled EL34 amp but I think you could do it with a triode strapped el84 as your input tube.
Attached Images
File Type: gif se el34.gif (8.3 KB, 858 views)
__________________
Gavin
  Reply With Quote
Old 15th January 2008, 11:21 PM   #12
Ipanema is offline Ipanema  Malaysia
diyAudio Member
 
Ipanema's Avatar
 
Join Date: Jun 2004
Location: KL
Default CD player to EL34 direct drive

THis is a noob question. Is it possible to ommit the tube driver stage and drive it directly from CD player output? How much voltage swing should present at the input of EL34 in order to drive it to full power in SE mode? Can you help to explain?

Thanks.
  Reply With Quote
Old 16th January 2008, 01:12 AM   #13
diyAudio Member
 
Join Date: Nov 2003
Location: NY
simple way of looking at it is to see the el34's bias voltage. if the grid is biased -30V at idle, it will take 30V peak input to drive it to 0V (maximum, for this discussion), which will also generate max. power (ignoring loading).

so a 2Vrms CD player output needs some additional voltage gain to drive it to full power.
  Reply With Quote
Old 16th January 2008, 01:19 AM   #14
Ipanema is offline Ipanema  Malaysia
diyAudio Member
 
Ipanema's Avatar
 
Join Date: Jun 2004
Location: KL
Hi zarniwoop,

Got you point. Thank you. 30Vpeak = 60Vpp. That would be impossible with most opamp. :-(

Thanks.
  Reply With Quote
Old 16th January 2008, 01:33 AM   #15
jnb is offline jnb  Australia
diyAudio Member
 
Join Date: Dec 2006
Furthermore, when the grid goes positive it will draw current and become a very difficult load. Not to say that an op-amp will drive it there but the stage before the output generally needs to be tough, preferrably with a low output impedance.

Quite often, a driver with gain followed by an output stage with an output transformer will have a net gain somewhere near one, anyway.
  Reply With Quote
Old 16th January 2008, 09:26 PM   #16
Empee is offline Empee  Netherlands
diyAudio Member
 
Empee's Avatar
 
Join Date: Sep 2006
Quote:
Originally posted by G
I don't think I have ever seen a DC coupled EL34 amp but I think you could do it with a triode strapped el84 as your input tube.
That's a nice idea !
I always liked the sound of an EL84...

...I wish I knew how to design that


But by the way,
does anybody have the schematic of the EL34 version of Alex Kitic's RH84 for me ? (RH34SE)

Elsewhere on this site there's multiple mentions of its existence,
but the schematic is nowhere to be found...


Cheers,

Empee
__________________
In the end, all is good
If it's not good, it's not the end
  Reply With Quote
Old 20th January 2008, 10:24 AM   #17
nesha is offline nesha  Serbia
diyAudio Member
 
Join Date: Jan 2007
Location: Beograd, Serbia
Hi, I m happy to see this topic got new attention and pulled out new interesting schematics, thanks. EL34 can probablly be coupled to the driver tube without cap by interstage transformer, like KT90 set ( Andrea Ciufolli).Is it better solution?
  Reply With Quote
Old 20th January 2008, 12:40 PM   #18
diyAudio Member
 
Shoog's Avatar
 
Join Date: Aug 2002
Location: Eire
There is a direct coupled version of Alex kitic's RH6550/RH88 which would be just what your looking for. Unfortunately it uses a huge wasteful cathode cap on the 6550.

I was just searching for the schematic, but it looks like Mr Kitic has taken down the site. He always struck me as a rather diagreeable fellow so he's probably taken his toys home.

How about this for the KT66.

http://www.diyaudio.com/forums/showt...472#post730472

Shoog
  Reply With Quote
Old 20th January 2008, 02:21 PM   #19
Empee is offline Empee  Netherlands
diyAudio Member
 
Empee's Avatar
 
Join Date: Sep 2006
Hi Shoog,

I understand and follow your feelings regarding Mr. K.

However, his RH84 design is very nice indeed and I've been
listening to that one for a loooooong time and still convinces me

By the way, was it you who did a PP-version of the RH84 ?
I like the idea behind that....


But anyway, back on-topic;
I think (although I cannot "calculate tubes" very much),
that a EL84 as drivertube would be a solution to the
difficultly-driven '34 question.

I seem to recall reading somewhere about EL84-driving-EL84
but don't know where ?!

wait....

wasn't it somewhere in the Meta Gizmo files.... ?
I'll have a look....
__________________
In the end, all is good
If it's not good, it's not the end
  Reply With Quote
Old 20th January 2008, 02:33 PM   #20
Empee is offline Empee  Netherlands
diyAudio Member
 
Empee's Avatar
 
Join Date: Sep 2006
nope,
it was diyparadise.com (and I ask you; what's in a name ?)

http://diyparadise.com/variation.html
__________________
In the end, all is good
If it's not good, it's not the end
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
capacitor coupled vs. direct coupled ouput hugobross Solid State 11 21st January 2011 01:56 AM
6sn7 direct coupled and transformer coupled neazoi Tubes / Valves 3 23rd May 2008 03:30 PM
6922 direct coupled to 2A3 gabriel611 Tubes / Valves 16 15th March 2006 09:25 AM
My first amp - a direct coupled 2A3 Wardsweb Tubes / Valves 51 3rd August 2003 04:22 AM
Can someone explain parafeed & direct coupled & a.c. coupled? mwmitchell Tubes / Valves 2 11th September 2002 01:10 PM


New To Site? Need Help?

All times are GMT. The time now is 11:39 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2