Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki 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

Matching tubes, what parameter to use?
Matching tubes, what parameter to use?
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 August 2019, 04:11 AM   #1
HarryY is offline HarryY  United States
diyAudio Member
 
HarryY's Avatar
 
Join Date: Aug 2017
Location: NY
Matching tubes, what parameter to use?
Default Matching tubes, what parameter to use?

It would seem that matching on their gain would be best? Is it? Or is there a better parameterto match them on?

Thank you
  Reply With Quote
Old 25th August 2019, 04:25 AM   #2
Tjj226 is offline Tjj226
diyAudio Member
 
Join Date: Dec 2012
I think THE best way to match tubes is to use a tube curve tracer and match tube curves. However its obviously unrealistic to test tubes this way. The more common approach is gm matching.
  Reply With Quote
Old 25th August 2019, 04:26 AM   #3
PRR is offline PRR  United States
diyAudio Member
 
PRR's Avatar
 
Join Date: Jun 2003
Location: Maine USA
What parameter *matters* in YOUR circuit?
  Reply With Quote
Old 25th August 2019, 07:54 AM   #4
gingertube is offline gingertube  Australia
diyAudio Member
 
Join Date: Oct 2004
Location: Adelaide South Oz
I don't match anything but output tubes.

With them I measure bias voltage and gm at the Valve tester manual suggested anode current value (and at the manual suggested anode and screen voltages) I collect up into different piles those which match gm within say 5% (if I have >10 tubes I might match tighter than this)

From each of those piles I then choose pairs with the closest bias voltage. So I match for gm first and then bias voltage second. Just my method. Others may do things differently.

Oh! I occasionally test twin triodes for balanced triode sections for Phase Splitter duty, again I match gm first and bias volts second.

Cheers,
Ian

Last edited by gingertube; 25th August 2019 at 07:57 AM.
  Reply With Quote
Old 25th August 2019, 02:29 PM   #5
HarryY is offline HarryY  United States
diyAudio Member
 
HarryY's Avatar
 
Join Date: Aug 2017
Location: NY
Matching tubes, what parameter to use?
Quote:
Originally Posted by Tjj226 View Post
I think THE best way to match tubes is to use a tube curve tracer and match tube curves. However its obviously unrealistic to test tubes this way. The more common approach is gm matching.
That's what brought this question up for me.

I was testing my tubes with a uTracer.

I have a pair of two year old Electro-Harmonix 12AU7 tubes that are so close that the plots from both sections as well as both tubes all overlay each other.

I have a second set of 12AU7 thats are labeled with only 'China" that are very nearly as good. That was a surprise since they came with a kit and I had just put them in my tube box to use a backup tubes.

Then I have a 'New" pair of Electro-Harmonix 12AU7 tubes that were bought as matched sections and matched against each other that are not matched either in sections or against each other.
  Reply With Quote
Old 25th August 2019, 09:32 PM   #6
Wavebourn is offline Wavebourn  United States
Anatoliy Lisovskiy
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Matching tubes, what parameter to use?
For SE amps I a first measure auto-bias on a resistor for a half of idle current, select closest tubes, then measure voltage drop on a resistor for intended idle current. Then select closest pairs from them.
__________________
!!!Warning!!!
Single Ended Class-A-Holism is addictive!!!
  Reply With Quote
Old 25th August 2019, 09:50 PM   #7
trobbins is offline trobbins  Australia
diyAudio Member
 
trobbins's Avatar
 
Join Date: Feb 2009
Location: Melbourne, Oz
Measure the distortion from your amplifying device - and tube roll (if lowest distortion is what you are finally after).
  Reply With Quote
Old 26th August 2019, 12:01 AM   #8
6A3sUMMER is online now 6A3sUMMER  United States
diyAudio Member
 
Join Date: Jun 2016
Matching a dual triode tube that is in a well designed 'LTP near perfect current sink' phase splitter might not be as important as . . . Matching a pair of very high transconductance output tubes in push pull output stage that uses a common cathode self bias resistor. Yes?

The application is often what determines the importance of a match.

For a pair of output tubes on SE mono-blocks that only use one output tube per amp, you might not need a close match as long as you have a good gain-balance control on the preamp.

Last edited by 6A3sUMMER; 26th August 2019 at 12:09 AM.
  Reply With Quote
Old 26th August 2019, 01:09 AM   #9
john_tracy is offline john_tracy  United States
diyAudio Member
 
Join Date: Apr 2008
Location: Columbia, Missouri
If your LTP pair is loaded with a CT inductor you'll need to match bias current within the DC offset tolerated by the inductor (I have a lot of those in my system).
__________________
"It is better to remain silent and thought a fool, then speak and remove all doubt." A. Lincoln
  Reply With Quote
Old 26th August 2019, 01:23 AM   #10
TonyTecson is offline TonyTecson  Philippines
diyAudio Moderator
 
TonyTecson's Avatar
 
Join Date: May 2003
Location: Maybunga, Pasig City
Matching tubes, what parameter to use?
i bought a quad of JJ 6L6GC tubes, in a circuit i used them in a pp amp that had individual cathode resistors, i was flabbergasted to find that bias was identical up to the first decimal point, how much more can you ask?...
__________________
planet10 needs your help: Let's help Ruth and Dave...http://www.diyaudio.com/forums/plane...ml#post5010547[B
  Reply With Quote

Reply


Matching tubes, what parameter to use?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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Matching 100 tubes ECC803S karsten21 Tubes / Valves 23 17th January 2017 01:10 PM
Help Matching RCA 5692 Tubes radiobarnhci Tubes / Valves 5 9th January 2016 11:21 PM
Matching tubes for PP h00hbt Tubes / Valves 3 19th May 2011 03:13 PM
pre-amp tubes: matching and care jadzuke Tubes / Valves 6 23rd January 2010 03:41 PM
Matching tubes pot in old Fenders slideman82 Instruments and Amps 2 27th October 2009 03:06 PM


New To Site? Need Help?

All times are GMT. The time now is 05:51 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki