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
Thread Tools Search this Thread
Old 3rd January 2007, 01:54 PM   #1
diyAudio Member
Join Date: Mar 2006
Location: sdf
Default Looking for EL34 PP Schematic Amp ? at least 35Watt

I'm looking for a schematic for Tube AMp using EL34 PP, which can create at least 35 Watt.

does anyone can reccomend me which Schematic ?
I'm looking for a simple Schematic less component to be use...

I done search but coudnl't found one.

be tube
  Reply With Quote
Old 3rd January 2007, 02:18 PM   #2
SY is offline SY  United States
diyAudio Moderator
SY's Avatar
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Work on those search skills- there's probably a hundred or two out there.

For low component count, it's hard to beat a Dynaco ST-70.
"It is difficult to get a man to understand something, when his salary depends upon his not understanding it." — Upton Sinclair
  Reply With Quote
Old 3rd January 2007, 02:35 PM   #3
kevinkr is offline kevinkr  United States
diyAudio Moderator
kevinkr's Avatar
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Take a look at my ST-70 mods page, configured for Ultralinear operation this circuit can do 40Wrms per channel with the right iron. Use the stock dyna power supply circuit design or upgrade choke and capacitors for a stiffer supply.


The schematics are in the old pcx format (I'll eventually get everything back up in pdf)

Use this great free graphics program to view, edit and print pcx, jpg, etc.


Note I have no affiliation with Faststone - just a happy user.

"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 3rd January 2007, 09:21 PM   #4
diyAudio Member
richwalters's Avatar
Join Date: Sep 2003
Location: Alps:Tube amp designs over 150W, SMPS guru.
As a start....... the standard Mullard 20 Watt amp with EL34's as it stands can be squeezed to give 30watts at 0.5% thd.

  Reply With Quote
Old 3rd January 2007, 10:01 PM   #5
AKN is offline AKN  Sweden
No snake oil
diyAudio Member
AKN's Avatar
Join Date: Aug 2005
Location: In the middle of Sweden
Send a message via MSN to AKN

Lundahl, well known maker of audiotransformers has one PP EL34 design presented on the companys web here.
/ Anders
  Reply With Quote
Old 4th January 2007, 01:11 AM   #6
diyAudio Member
Join Date: Mar 2006
Location: sdf
thanks for pointing the Dynaco, yes I agree this brand is my first look and the only simplest schematic I found.

I only download and see the schematic only not the power supply schematic.. I miss something ?

I wonder how to configure in linear and triode mode ?

actually I'm looking for the Triode mode that can do 35Watt at least.

I don't think I can found the Dynaco Output transformer here, can I use other like lundahl or tango ? which model ?

or what's the specification of that Output transformer ?

other questions, how can I modify the bias into auto bias ? possible ?

Kevin, I don;t think I can modify the schematic my self, all I can do is build base on the schematic, if you can show me the final schematic like Triode mode (can you modify to 35W plus ?), auto bias and PSU Schematic.

be tube
  Reply With Quote
Old 4th January 2007, 02:00 AM   #7
diyAudio Member
Join Date: Apr 2004
Location: Monroe Township, NJ
I'm looking for the Triode mode that can do 35Watt at least.

No way are you going to get 35 W. from a PP pair of triode wired EL34s. You'll be hard pressed to get 35 W. from a PP pair of triode wired KT88s. A near Class "B" operating point is necessary.

What sort of speakers are you planning on using? Honest 91 dB. efficient speakers need only 15 WPC, in most rooms.
Eli D.
  Reply With Quote
Old 4th January 2007, 02:36 AM   #8
diyAudio Moderator Emeritus
ray_moth's Avatar
Join Date: Jan 2004
Location: Jakarta
As Eli said. Even two pairs of EL34 in triode mode parallel PP probably wouldn't quite make it. 6550 or KT88 in triode mode parallel PP could do it, though.
  Reply With Quote
Old 4th January 2007, 06:53 AM   #9
diyAudio Member
Join Date: Mar 2006
Location: sdf
thanks guys,
I will use regular speaker like 80 Db sensitifity.

I guess I should look the schematic using 6550, KT88 is more expensive.

ok, ELI or anyone can suggest me TRIODE PP using 6550 at lest 35W ?

be tube
  Reply With Quote
Old 5th January 2007, 02:24 AM   #10
diyAudio Member
Join Date: Jan 2006
Location: SAO PAULO - SP
Hi Calico88 ,

If you are looking for a simple , cheap and good quality
unit ,and an excellent cost / benefit ratio , try the following :

1st option : DYNACO STEREO 70
Uses one 7199 and two EL34 per channel and can
deliver 35 W / ch .

2nd option : If you don’t want to use the expensive and
hard to find 7199 tube , I suggest the DYNACO MARK II
Uses one 6AN8 and two EL34 per channel and can
deliver 35 W / ch .

3rd option : The MULLARD’S 520
Uses one EF86 ( hard to find , only Svetlana manufactures
it nowadays ) , BUT with “minor” changes in the resistors
values you can use the 6AU6 ( cheap and easy to find ) ,
yet uses one ECC83 (12AX7) and two EL34 per channel
and can deliver ( squeezed ) 30 W / ch of good quality sound .

Obviously , there is many , many more circuits that can
attend your previously specified characteristics , BUT the
3 examples above are simple , relatively cheap , the TRANS-
FORMERS are very , very easy to find , easy to build , and the
final result will surprise you .
NOTE : The 3 options above are ULTRALINEAR circuits , that
means , they are a good compromise between the pentode
power and the triode linearity , exactly what you are looking for .

Regards ,

  Reply With Quote


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
SE EL34 schematic HELP: from two 6SL7's to One? ambience exists Tubes / Valves 13 14th March 2010 05:48 PM
Looking for Schematic 6550 tube amp triode mode more than 35Watt ? calico88 Tubes / Valves 26 10th August 2009 02:49 PM
Schematic for GU-50, EL34, 6J32P ??? Dxvideo Tubes / Valves 3 24th September 2007 10:51 AM
se 6c33c or se el34 schematic karma Tubes / Valves 10 2nd July 2005 05:40 PM
el34 se schematic opinion trancy Tubes / Valves 3 21st April 2004 03:52 PM

New To Site? Need Help?

All times are GMT. The time now is 07:32 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