GZ37 Substitution? - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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 2nd July 2005, 08:33 PM   #1
diyAudio Member
Join Date: Dec 2004
Location: LA
Question GZ37 Substitution?

I'm planning to build the Angela SE 6SL7->EL34 (triode strapped) amp. Their designs call for GZ37 rectifiers, but as this is to be a low-cost project, I don't want to chase NOS tubes down at high $$.

I'm thinking a 5AR4/GZ34 might be a decent replacement here-- draws 1A less current, but is rated for 160mA Irect compared to the GZ37's 250. So perhaps a 5U4G, rated for 225mA Irect would be preferable, and I have some of those around.

Thanks in advance for any advice.
  Reply With Quote
Old 2nd July 2005, 10:48 PM   #2
diyAudio Member
Join Date: Jan 2005
Location: S.C.
Hackensack , I have two GZ37's that I purchased from Ned at triode tubes in early 1990s when I was updating my Dynaco MK2s.
I did not use them because the top covers would not fit.
If your interested email me. Thanks
  Reply With Quote
Old 2nd July 2005, 10:52 PM   #3
diyAudio Member
Join Date: Apr 2004
Location: Monroe Township, NJ
Check the data sheets out. The 5AR4/GZ34 is rated for a 250 mA. draw. The GZ37 is rated at 275 mA. into a cap. I/P filter and 350 mA. into a choke I/P filter. Also, the GZ37 data sheet says 4 muF. max. for a cap. I/P filter.

The forward drop in a GZ37 is greater than that in a GZ34. So, the B+ rail voltage will be somewhat higher. Current production 5AR4s have improved significantly of late and that's what I'd use.
Eli D.
  Reply With Quote
Old 4th July 2005, 05:18 PM   #4
diyAudio Member
Join Date: Dec 2004
Location: LA
Thanks for the replies!
I will most likely follow Eli's advice, however, I would also consider Freddy's offer, but the diyaudio mail function is turned off for him.
  Reply With Quote
Old 4th July 2005, 07:18 PM   #5
EC8010 is offline EC8010  United Kingdom
diyAudio Moderator Emeritus
EC8010's Avatar
Join Date: Jan 2003
Location: Near London. UK
Originally posted by Eli Duttman
Also, the GZ37 data sheet says 4 muF. max. for a cap. I/P filter.
Which data sheet would that have been? My Mullard data sheet simply gives data using 4uF as a reservoir, but given that the data sheet was from 1958 (and probably an update of an earlier one), perhaps that's not indicative? The peak current ratings suggest that it ought to be equivalent to a GZ34 - it just uses more heater current.

Of course, you could always use a pair of 6CL3/6CK3 or 12CL3/12CK3, which are substantially beefier than GZ34, and in your neck of the woods, probably cheaper.
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
  Reply With Quote
Old 4th July 2005, 11:30 PM   #6
diyAudio Member
Join Date: Apr 2004
Location: Monroe Township, NJ
The 5R4 can deliver plenty of current too. 4 muF. is max. for that type too. Arc over at start up is NOT good.

There are reports about the GZ37 sounding mediocre when used as a substitute for the GZ34. My hunch is that the tube is stressed, even if it does not arc over with a substantial filter cap.

The data sheet I've seen was published by Chelmer Valve.
Eli D.
  Reply With Quote
Old 4th July 2005, 11:42 PM   #7
SHiFTY is offline SHiFTY  New Zealand
diyAudio Member
SHiFTY's Avatar
Join Date: Jul 2002
Location: New Zealand
If you want an even better sub get a mullard GZ33, that is the holy mother of god rectifier that is indestructible by conventional means.

But even a GZ34 should have a life of several decades used with 40 or 60uF input cap...
  Reply With Quote
Old 25th April 2014, 09:37 PM   #8
diyAudio Member
Join Date: Apr 2014
Location: Eugene,Or
Hi I have a Dynaco VTA ST-120 . It is a Bob Latino modified st-70 that Bob himself says you can run the GZ 37 as a drop in rep also it can run kt-88 kt 90 kt 120 tubes .It is 60 wpc . I run the kt 88 at .55volts but the kt 120 in this amp I run at .6volts nice
  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
Genuine Mullard CV378 (GZ37) rectifiers for sale x4 Fanuc Swap Meet 12 10th June 2009 02:10 PM
Fs: 6j5g, Gz37, 53ku (nos!!!) cartman Swap Meet 6 30th January 2008 05:34 AM
6N1/6N3 substitution woodturner-fran Tubes / Valves 7 31st January 2007 01:15 PM
GZ37 replacement? tomchaoda Tubes / Valves 4 20th April 2005 09:42 PM
Substitution MOS for Aleph 3 Miles Teg Pass Labs 7 19th September 2001 04:59 PM

New To Site? Need Help?

All times are GMT. The time now is 09:32 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2