An Ultra -linear question - 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 16th July 2004, 01:59 PM   #1
diyAudio Member
Join Date: Nov 2003
Location: Genova, Italy
Default An Ultra -linear question

Hi all,

I have a serious problem with the concept
of ultralinear characteristic curves.

Suppose I have to find the static working point
of an Ultralinear connected SE amplifier.

I'll simly use the triode-connected plate curves since
in static condition there is no difference between
plate voltage and G2 voltage (a part from the different
due to the DC loss in that part of the trafo).

Well, but in dynamic conditions the voltage at
g2 is a definite fraction (e.g. 40%) of that
at the anode so the behaviour of the tube is
very different and the triode curves become useless.

However, I always read that the Ultralinear curves
are traced by applying, in a slow variable way with
two different generators, two different voltage to
g2 and the anode respectively, being one 0.4 time
the other. but this is very different from the real
static case of trasformer loading where the
static voltages, a part from the fall in the primary,
are equal.

So, it appear that the ultralinear curves refer to
the dynamic case. Certainly, if one uses the UL curves
to find tha static point, he will go in troubles and
obtain wrong results.

It seem , may be, that we need a different
dynamic plot for every static work point.
But it is impossible.

I am very confused.

Can somebody help me ?

thak you in advance

Federico Scarpa
  Reply With Quote
Old 20th July 2004, 03:54 PM   #2
diyAudio Member
Join Date: Nov 2003
Location: Genova, Italy

Also your opinions on the subject are welcome.

  Reply With Quote
Old 21st July 2004, 09:40 AM   #3
316a is offline 316a  England
diyAudio Member
316a's Avatar
Join Date: Dec 2002
Location: West London
Default UL

Originally posted by fscarpa58

Also your opinions on the subject are welcome.

Hello ,
I have also been pondering on the same subject as I'm about to press a quad of EL38 into UL service . The EL38 datasheet only shows pentode curves and this type does not seem to be used often for audio so I have been using comparisons of other similar valves such as the 807 and EL34 . On the Audiomatica website there are characteristic curves for pentode , UL and triode for the EL34 and 807 , may be worth a look


  Reply With Quote
Old 21st July 2004, 04:53 PM   #4
diyAudio Member
Join Date: Nov 2003
Location: Genova, Italy
Hi 316a, thank you

I know those curves but I really
do not understand static versus
dynamic description of UL connected tubes.

It seems impossible to me to
represent both static and dynamic UL behavior
with the same curves.

I'll continue to scan the web.


  Reply With Quote
Old 29th July 2004, 12:12 PM   #5
diyAudio Member
Join Date: Nov 2003
Location: Genova, Italy
I don't find anything on the subject
clearly explaining UL plate curves.

any idea?

  Reply With Quote
Old 29th July 2004, 12:28 PM   #6
SY is offline SY  United States
diyAudio Moderator
SY's Avatar
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 2
I guess I'm confused by the confusion!

The static points need to be determined by static curves. Analysis of the dynamic operation requires dynamic curves. Remember, in the case of UL, the voltages are being applied via a transformer by definition. So they are different in that sense than pentodes or triodes, where there's really no difference between the AC and DC voltages.

As a side note, EL38s work very, very well with a 6600 ohm p-p, 43% UL taps, and about 490V on the plate. I got 45 watts out of this configuration.
"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
  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
Lundahl LL1620 SE-OPT : Ultra linear ? jim Tubes / Valves 1 14th May 2009 04:02 PM
Ultra-Linear Zen flg Pass Labs 9 12th December 2007 05:01 PM
EL 34 30W ultra linear GAK Tubes / Valves 70 24th November 2004 11:57 AM
Ultra linear g2-anode suppress richwalters Tubes / Valves 3 30th November 2003 05:49 PM

New To Site? Need Help?

All times are GMT. The time now is 09:36 PM.

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