replace EL34 with EL37 !? - 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 24th December 2011, 08:04 PM   #1
athode is offline athode  Canada
diyAudio Member
 
Join Date: Dec 2011
Location: Terrebonne,QC
Default replace EL34 with EL37 !?

Hi! I want to know if I can replace the EL34 output tube on my eico HF-89 with EL37 tube and if I need to do some modification on resistor value on the circuit.
  Reply With Quote
Old 24th December 2011, 08:40 PM   #2
diyAudio Member
 
Join Date: Aug 2010
Location: Near Eindhoven, the sanctum of the pentode. and among that other things.
Send a message via Skype™ to v4lve lover
why would you EL37 are pretty rare classics . simmilair to 6l6
el34 can be had much easier
  Reply With Quote
Old 24th December 2011, 08:54 PM   #3
athode is offline athode  Canada
diyAudio Member
 
Join Date: Dec 2011
Location: Terrebonne,QC
It's because I have 4 mullard EL37 and I want to hear it!
  Reply With Quote
Old 24th December 2011, 09:24 PM   #4
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
You may need to reduce the plate voltage significantly, and the grid bias voltage probably needs to be increased into 6L6 territory, -40V or more.

The Mullard EL37 is reputed to be an excellent performer, and I can understand your curiosity, just make sure that you are operating them inside of acceptable plate dissipation, voltage and current values. Since they are yours obviously you can do anything you want with them, and were I you I would try them and if I liked the results would use them. Museum pieces are fine, but...
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 24th December 2011, 09:33 PM   #5
diyAudio Member
 
vinylkid58's Avatar
 
Join Date: May 2005
Location: Victoria, B.C.
Quote:
Originally Posted by athode View Post
It's because I have 4 mullard EL37 and I want to hear it!
Luckeeeee!

jeff
  Reply With Quote
Old 24th December 2011, 09:50 PM   #6
athode is offline athode  Canada
diyAudio Member
 
Join Date: Dec 2011
Location: Terrebonne,QC
With the original configuration of the eico HF-89 (EL34) plate voltage is 487v and bias voltage is -46v
  Reply With Quote
Old 25th December 2011, 03:58 AM   #7
diyAudio Member
 
Join Date: Jun 2011
ok, swap the 15k and 10 resistor in bias

change B+ supply to full wave bridge type

Bias at approx -15V @ 275 V B+
-13.5@ 250 VB+

depends where the B+ lies when you change the power.
Attached Images
File Type: jpg hf89wEL37.jpg (851.2 KB, 538 views)

Last edited by DavesNotHere; 25th December 2011 at 04:06 AM. Reason: bias correction
  Reply With Quote
Old 25th December 2011, 10:22 AM   #8
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
I did the swap in an HF87 (which had previously been modified for fixed bias). The EL37s performed spectacularly well. 45 watts at midband.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 25th December 2011, 10:42 AM   #9
diyAudio Member
 
h00hbt's Avatar
 
Join Date: Jun 2007
Quote:
Originally Posted by DavesNotHere View Post
ok, swap the 15k and 10 resistor in bias

change B+ supply to full wave bridge type

Bias at approx -15V @ 275 V B+
-13.5@ 250 VB+

depends where the B+ lies when you change the power.
Just curious, what would the primary of the OPT be?

Cheers
__________________
/H
  Reply With Quote
Old 25th December 2011, 02:42 PM   #10
diyAudio Member
 
Join Date: Sep 2011
Does EL34 really same as 6L6 in plate supply and the grids cause, i am still thinking to change El34 into 6L6> In case i had read the data sheet from the wed and i saw the class a voltage supply is really the same but the output power is little bit different> Could any one taught me < Thanks A Lot~
  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
FS: Matched Quad E.H. EL37 Tubes Bengali Swap Meet 2 16th March 2010 10:21 PM
El34 PP Vs. El34 PSE alexmoose Tubes / Valves 47 6th September 2006 05:44 PM
Replace el34 with 6p3s ampere Tubes / Valves 1 28th March 2006 12:50 PM
EL37 ebay auction draget Swap Meet 0 9th August 2005 12:42 PM
what do I replace...? 9am53 Tubes / Valves 10 5th May 2005 02:20 AM


New To Site? Need Help?

All times are GMT. The time now is 09:24 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