parallel tubes - 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 26th November 2014, 02:30 AM   #1
diyAudio Member
 
mr2racer's Avatar
 
Join Date: Jul 2009
Default parallel tubes

Is it possible to parallel tubes? This was a post to find older posts. But nothing came up. I would like to drive a SE 6550 using 6CG7. I was wondering if you could use the triode halves in paralell using a common plate resistor and a common cathode resistor? Would it be a bad idea?

Yes, even when I was six I asked a million questions.

Kevin
__________________
Artificial intelligence is no match for natural stupidity- Red Green

Last edited by mr2racer; 26th November 2014 at 03:00 AM.
  Reply With Quote
Old 26th November 2014, 02:30 AM   #2
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Yes...
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 26th November 2014, 02:31 AM   #3
rayma is offline rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Location: Upper midwest
Quote:
Originally Posted by mr2racer View Post
Is it possible to parallel tubes
Sure, with separate cathode resistors.
  Reply With Quote
Old 26th November 2014, 03:12 AM   #4
diyAudio Member
 
mr2racer's Avatar
 
Join Date: Jul 2009
Why separate cathode resistors?
__________________
Artificial intelligence is no match for natural stupidity- Red Green
  Reply With Quote
Old 26th November 2014, 03:46 AM   #5
diyAudio Member
 
azazello's Avatar
 
Join Date: Aug 2008
Location: Bulgaria
......to make the same tube currents......
__________________
Projects: OTL-OCL 6AS7 Gen. Electric, SEs 2A3 RCA, 300B JJ, 6S4S, 4P1L, EL11 Telefunken, 6AS7 RCA, 6S33S, 6S41S, 6S19P, E84L Siemens, E236L Telefunken, headphone ampl. OTL Loftin White 6AS7 RCA,... PPs 6005 Gen. Electric, EL34 Mullard, 6L6....
  Reply With Quote
Old 26th November 2014, 07:51 AM   #6
Keit is offline Keit  Australia
diyAudio Member
 
Join Date: Feb 2014
Location: Australia
With parallel power tubes, the modes for HF or VHF parasitic oscillation abound. This is usually easily dealt with though. Feed paralleled screens via individual screen stopper resistors installed right at the sockets. A few hundred ohms is typical. In stubborn cases connect to anodes via chokes in parallel with resistors like transmitter practice.

Resistors in series with the control grid should ALWAYS be installed individually for each paralleled tube.

If you don't have a CRO with which to detect HF or VHF oscillation, parasitic oscillation shows up as unexpectedly bad distortion much worse than the circuit should provide. If the distortion gets noticeably worse or better with a plastic coated meatl plate brought near the tube or tube socket in question, you've got parasitic oscillation. Or you can use a scanner radio to pick it up.


If you are not talking about power tubes, but small triodes in driver stages or preamps (eg 12AU7, 6CG7) there should be no problem, as their gm is low - paralleling with common load resistors is often done. It's ok to use a common cathode bias resistor if the two triodes are in the same twin triode.

Last edited by Keit; 26th November 2014 at 07:57 AM.
  Reply With Quote
Old 26th November 2014, 10:13 AM   #7
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
There's no problem doing that for the application you're talking about.
__________________
"Pity, wrath, heroism, filled them, but the power of putting two and two together was annihilated."- EM Forster
  Reply With Quote
Old 26th November 2014, 10:35 AM   #8
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
what is your take on the conrad johnson ART? ten plates in parallel using 5 6dj8 tubes...
or they must have a lot of these tubes to get rid of?

Click the image to open in full size.
__________________
the best advertisement for a good audio design is the number of diy'ers wanting to build it after all the years....never the say so of so called gurus....
  Reply With Quote
Old 26th November 2014, 02:56 PM   #9
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Nice low source impedance.. lol
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 26th November 2014, 10:12 PM   #10
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
when paralleling tubes, which is more important?
a. tubes are of same plate current, or
b. tubes are of same plate voltage...
__________________
the best advertisement for a good audio design is the number of diy'ers wanting to build it after all the years....never the say so of so called gurus....
  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
Parallel Driver Tubes? oldschooltube Tubes / Valves 11 11th June 2014 11:32 AM
Driving Parallel Tubes CV6045 Tubes / Valves 10 30th July 2013 10:38 AM
parallel tubes Nikon1975 Tubes / Valves 15 12th February 2010 05:36 PM
Parallel output tubes Klimon Tubes / Valves 22 11th February 2007 02:18 PM
Parallel Two Tubes jwatts Tubes / Valves 1 24th March 2006 12:56 PM


New To Site? Need Help?

All times are GMT. The time now is 01:16 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright 1999-2015 diyAudio

Content Relevant URLs by vBSEO 3.3.2