ETM connected EL/PL509 in T8 OTL-OCL amplifier - how? - 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 15th January 2004, 10:54 PM   #1
diyAudio Member
 
aparatusonitus's Avatar
 
Join Date: Jan 2004
Location: Split, Croatia
Default ETM connected EL/PL509 in T8 OTL-OCL amplifier - how?

Hy all,

I am planing to build T8 OTL-OCL from Rozenblit, but I would like to know how to connect EL/PL509 (EL/PL519) output tubes alla Tim de Paravacini ie in Enhanced Triode Mode (ETM)? Would this
particular amplifier benefit from such connection, and how to bias output tubes if everything else is the same as in original design?

Thanks, Ivo
  Reply With Quote
Old 17th January 2004, 12:07 AM   #2
diyAudio Senior Member
 
fdegrove's Avatar
 
Join Date: Aug 2002
Location: Belgium
Hi,

Not that I've actually double tested this but from what I read, ETM augments Zo.

Not something you look forward to in an OTL amp....

Cheers,
__________________
Frank
  Reply With Quote
Old 17th January 2004, 07:04 PM   #3
diyAudio Member
 
aparatusonitus's Avatar
 
Join Date: Jan 2004
Location: Split, Croatia
Hi Frank,

Thanks, I presumed there is a catch somewhere. Anyway, do you know how to connect those tubes in ETM or maybe know where I can get more information about EMT (except in this forum of course).

Ivo
  Reply With Quote
Old 17th January 2004, 11:38 PM   #4
diyAudio Senior Member
 
fdegrove's Avatar
 
Join Date: Aug 2002
Location: Belgium
Hi,

Conventional triode connected pentodes have the second grid tied to the anode, which results in a halfway compromise between a pentode and a triode. This neither has the efficiency of the pentode, nor the linearity of the triode. Tim de Paraviciniís Enhanced Triode Mode (ETM) goes one step further, and creates a true, highly linear triode from a robust pentode tube.

Instead of driving the normal Grid One with signal, this is tied down to the cathode, and thus becomes an invisible, transparent element, and part of the cathode. Signal is fed into the tubeís Grid Two, and in this configuration, Grid Three has no effect - it can either be connected to earth, or left floating. The ETM behaves like a true triode and is in fact more linear than the majority of directly heated triodes. Compared with the latter, it has the additional advantage of being a tough, more robust tube, capable of much longer operational life.


********************************
Dixit Edouardo De Lima:

Enhanced triode mode uses the grids of a pentode in a different manner. When compared to conventional triode connection, the final result usually behaves as a triode with lower levels of distortion but much increased plate resistance and naturally much higher output impedance. The plate resistance in this connection is just about the same as regular pentode operation.

**********************************
Dixit Andrea Ciuffoli:

Enhanced Triode mode, big names (Tim de Parravicini) adopted this kind of topology. It has a good output swing, but the inverted usage of the grids generates a very high output impedance. such a situation forces the usage of a power tetrode/penthode for driving the output. Furthermore the stage linearity is pretty questionable.

**********************************
Svetlana document re. ETM

http://www.svetlana.com/docs/TechBul...hnoteNo33.html

Note that G1 is grounded and G3 is tied to the cathode.

***********************************

Dixit FDG:

So, the disadvantage seems to be the higher Zo when connected as per TDP.
But, what happens to the Zo if we were to connect G3 to the anode?

This + my comments is what I found...

As I never plotted such valve the way I suggest, I am at a loss.

My logic is only a guess, so don't build on it...

Cheers ,
__________________
Frank
  Reply With Quote
Old 18th January 2004, 10:03 AM   #5
diyAudio Member
 
aparatusonitus's Avatar
 
Join Date: Jan 2004
Location: Split, Croatia
Thanks Frank, this is quite helpfull!
BTW, could someone elaborate Frank's idea:

But, what happens to the Zo if we were to connect G3 to the anode?

Ivo
  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
More Grunt from Aikido Needed to drive PL509's Philwait Tubes / Valves 5 6th July 2009 08:49 AM
Not connected yet Andy G Multi-Way 2 14th October 2006 09:20 AM
Never-connected clone? analog_sa Solid State 39 17th May 2004 11:31 AM
Must I have a TV connected? Timn8ter Digital Source 2 16th March 2004 06:27 PM
Would I know if my caps are not connected? sounder Chip Amps 4 24th September 2003 08:29 PM


New To Site? Need Help?

All times are GMT. The time now is 12:42 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