6973 VS 6CZ5 substitute - 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 25th October 2010, 12:04 AM   #1
diyAudio Member
 
Join Date: Oct 2010
Default 6973 VS 6CZ5 substitute

The 6CZ5 is supposed to be a good substitute for the 6973 tube. I tried this substitution in an old AMI jukebox amplifier, and the 6CZ5s over heated and turned cherry red. Can any one spot the problem using them in this circuit? (The pin voltages are in the table.)


Click the image to open in full size.

BTW, I bought a set of Electro-Harmonix 6973s, and they work fine. (Funny, they don't look anything like the RCA 6973s.)

Retired EE who never played with tubes before, that's how long SS has been out!

Bobby Dipole
  Reply With Quote
Old 25th October 2010, 01:29 AM   #2
diyAudio Member
 
leadbelly's Avatar
 
Join Date: Dec 2002
Location: Calgary, Alberta
Who told you it was a sub? Lower dissipation & voltage ratings, and different pinout. I can't see what you tried to attach.
__________________
Aerodynamics are for people who can't build engines. Enzo Ferrari
  Reply With Quote
Old 25th October 2010, 06:25 AM   #3
diyAudio Member
 
Join Date: Oct 2010
Quote:
Originally Posted by Bobby Dipole View Post
The 6CZ5 is supposed to be a good substitute for the 6973 tube. I tried this substitution in an old AMI jukebox amplifier, and the 6CZ5s over heated and turned cherry red. Can any one spot the problem using them in this circuit? (The pin voltages are in the table.)

BTW, I bought a set of Electro-Harmonix 6973s, and they work fine. (Funny, they don't look anything like the RCA 6973s.)

Bobby Dipole
Oh, I forgot to mention that I tied pins 1 & 8 together at the sockets so the 6CZ5 screen grid was taken care of.

Bobby Dipole
  Reply With Quote
Old 25th October 2010, 11:33 AM   #4
45 is offline 45  Italy
diyAudio Member
 
45's Avatar
 
Join Date: Dec 2008
Location: UK
Quote:
Originally Posted by leadbelly View Post
Who told you it was a sub? Lower dissipation & voltage ratings, and different pinout. I can't see what you tried to attach.

For istance, many sellers try to sell 6CZ5's as substitutes to increase outrageously the selling price.....

45
  Reply With Quote
Old 25th October 2010, 06:44 PM   #5
diyAudio Member
 
smoking-amp's Avatar
 
Join Date: Dec 2001
Location: Hickory, NC
http://scottbecker.net/tube/sheets/137/6/6CZ5.pdf

http://scottbecker.net/tube/sheets/049/6/6973.pdf

I see the 6CZ5 is rated for 12 Watts for class A1 audio, and 10 Watts Vertical Sweep.

6973 audio rating 12 watts in class AB1, pin 8 is different in base diagram, although 6CZ5 shows an unspecified internal connection for pin 8. Curves virtually identical. Voltage ratings on the 6973 are higher (440V plate, 330V g2), but are specified as design maximum ratings, whereas the 6CZ5 are specified as design center ratings (350V, 285V). 6CZ5 gives a 2200V peak plate voltage rating, so I would guess that the 440V design max plate V of the 6973 can be met OK.

Sure do look like the same tube except possibly pin 8. Maybe you just have a defective tube, a corroded g1 pin maybe.

I suggest checking pin 8 on the 6CZ5 to see if it really does connect to g2 and to pin 1. Easy to check visually and also with an Ohm meter. Tying pins 1 and 8 together will only work if pin 8 really is connected to g2 (or nothing), otherwise "smoke and flames" likely.
__________________
Without MS, how would we live without all those hackers?

Last edited by smoking-amp; 25th October 2010 at 07:11 PM.
  Reply With Quote
Old 25th October 2010, 10:00 PM   #6
45 is offline 45  Italy
diyAudio Member
 
45's Avatar
 
Join Date: Dec 2008
Location: UK
Quote:
Originally Posted by smoking-amp View Post
so I would guess that the 440V design max plate V of the 6973 can be met OK.
Possibly you can do that and not only with these tubes. For example I can tell you that a 6V6GT can easily take up to 420V anode voltage. However it is "approximately possible".......that sooner or later the tube will fail and when it survives its life is shorter than average.

45
  Reply With Quote
Old 26th October 2010, 01:01 AM   #7
diyAudio Member
 
smoking-amp's Avatar
 
Join Date: Dec 2001
Location: Hickory, NC
45:
"However it is "approximately possible".......that sooner or later the tube will fail and when it survives its life is shorter than average."

Almost certainly likely, beyond any doubt!

Maybe the original poster could tell us what screen voltage it is actually running at?
I notice that 6CM6 has the same specs too, and the similar base pinout with NC on pin 8. What gives with all these 9 pin 6V6s? Maybe they just sorted them into bins: sloppy, good, excellent.
Let's see: 6CM6 $5, 6CZ5 $7, 6973 $35, Ah Hah!
__________________
Without MS, how would we live without all those hackers?

Last edited by smoking-amp; 26th October 2010 at 01:24 AM.
  Reply With Quote
Old 26th October 2010, 03:17 AM   #8
diyAudio Member
 
smoking-amp's Avatar
 
Join Date: Dec 2001
Location: Hickory, NC
and 12AB5 for $3. Maybe had to do with how microphonic?
__________________
Without MS, how would we live without all those hackers?
  Reply With Quote
Old 26th October 2010, 06:47 AM   #9
45 is offline 45  Italy
diyAudio Member
 
45's Avatar
 
Join Date: Dec 2008
Location: UK
Quote:
Originally Posted by smoking-amp View Post
Let's see: 6CM6 $5, 6CZ5 $7, 6973 $35, Ah Hah!
Are these your prices or real prices? I have not been able to find 6cz5's for 7$...

45
  Reply With Quote
Old 26th October 2010, 03:28 PM   #10
diyAudio Member
 
Tom Bavis's Avatar
 
Join Date: Jun 2002
Location: Macedon NY
Findatube.com: $5, $9, $21. AES: $6, $10, $50. Vacuumtubesinc: $5.50, $8, "Call". ESRC: $5, $7, $35.
  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
2SC5198 substitute gruni Solid State 5 1st October 2010 01:49 PM
SqueezBox substitute jkeny Digital Source 123 13th December 2009 02:05 AM
2SD873 substitute ? garnet Parts 1 27th September 2007 10:32 AM
Substitute for mosfet darkm4n Parts 2 23rd April 2007 11:57 AM
Substitute to 2N5484 Ryssen Parts 1 18th April 2007 01:58 AM


New To Site? Need Help?

All times are GMT. The time now is 06:02 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