Lets face it gents, we are the thermionic green
berets: a small group of dedicated fierce warriors ready to go anywhere and do anything to
accomplish our mission. Because we are the vanguard of the audio revolution we know more
about the edge of the audio arts for a good reason.... we are creating it. Because Karma
rules, we, the throbbing phallus of the audio arts, are rewarded for our work. It is our
job to question and challenge every conventional notion about design and continue to
experiment. I remind you of my experiments with making interconnects and speaker cables
with Radio Shack ultra-thin magnet wire and solid silver wire...which was exactly opposite
of what everyone else was doing. So it is our job to question and experiment.
According to audio orthodoxy torroid output transformers dont work well.
It is also well known that DHT SETs dont work well. I also want to suggest that all
vinyl systems dont work well. You might say that they only things that sound really
juicy are those things that dont work well....according to the bogus audio
orthodoxy. So let us be skeptical about torroid OPTs, but the only thing we can trust is
our heightened sense of music.
During the 1970s when I had to own every tube amplifier ever made, I bought a
pair of Gotham Audio cutting head amplifiers just because they had the rara avis...
torroid output transformers. Soon after that I was shown pictures of the David Hafler
never manufactured torroid OPT Dynaco MkIVs, and that is the last I heard
about torroid output transformers. Have you ever seen any tube amp with big round OPT?
Probably not, because the orthodoxy is that torroid OPTs have a family of
electrical problems that make them unsuitable for high quality audio.
Of course we all know how torroid power transformers and chokes have distinct
advantages and are much appreciated....and more and more SET triode bros are using
In December I was contacted by Menno van de Veen ( a serious Dutch thermionic
techno-shaman who has written a great book on tube amplifier design available from Plitron
and a dude I first made contact with at New York Audio Labs) who designs torroids of all
sorts for Plitron Manufacturing in Canada. Menno was surfing the Triode Guild web site and
wanted me to know that he had developed a new torroid OPT for single-ended circuits, and
claimed that he had overcome many of the limitations of the torroid OPT
orthodoxy and believed that his new design had significant performance
advantages. Was I interested? Which is like asking me if I would you like to take a shower
with Cameron Diaz? I suggested that he send me a pair of 5K models for 300Bs (Please
remember that my hunt, as Guildmeister, is for the musical shadows that surround notes,
and not power. My formula is 5K transformers, at about 360 Volts at 60 ma in SETs), and
was informed that it would be a few months before the first were available, so I waited.
The idea of being one of the first to hear a SET torroid output amp was potentially very
I then emailed my thermionic techno-shamans brothers around the world and asked
if anyone had any experience with single-ended torroid OPTs and no one had a clue...not
even the lofty Sir Scott Frankland. In other words, Menno had created the first of its
kind. By this time I received lots of technical papers from Menno explaining his
breakthrough which was so technical that I didnt understand most of it. According to
Howard Gladstone president of Plitron, this SET OPT has been a two year project.
What I find so interesting about Mennos design work is that he wrestles
with OUR essential artistic paradox: to a serious audio engineer DHT-SETs dont make
any sense, and from their oscilloscope point of view they are right. To those who live by
their ears, and not by their oscilloscope, DHT-SETs make profound sense because they
produce such rich triode cream, and we wonder why engineers love their push/pull
amplifiers. Dont they want to cream more economically and dance naked in the stars?
But Menno is a righteous cool dude, and he recognizes that something is going on
in the world wide craze for DHT-SETs, and is working to design a better OPT
meaning.... wider bandwidth, more linear and one with better transient response, and one
that interfaces with the speaker load with less variation.....recognizing the positively
prehistoric nature of the circuits we love. Never forget this: When it comes to musical
beauty YOU know best.
A QUICKIE SURPRISE
At 7:00 PM on December 14, 1999 I heated my soldering iron and put my custom
300B SET on the operating table, and in about fifteen minutes my normal output
transformer was disconnected the Plitron unit rigged. The other amp stayed stock. My
comparison was made with the KR 300BXL tubes.
I am so vain that I think this song is about me, but quite frankly it
doesnt take much on my system to discern differences in gizmos. After only listening
for 30 minutes my initial impression is that Menno and Plitron have been very successful
and.... the transformer hadnt aged in yet, and I didnt even experiment to find
its sweet spot.
These were my quickie responses: bass response like the Sun push/pull and the
tonal quality of the Tamura iron....but not quite. Better high frequency response and a
very wide soundstage than all of the other SET OPT I have in my collection.
After months of listening I am asserting that all of those who are insisting
that torroid OPTs, and especially the ones for SETs, dont work properly need a
serious attitude adjustment....at least the Plitron design. So let me make the point
plain: Mennos design creates a unique aural matrix that is extremely creamy, but it
is a completely different form of SET cream, and that is what is so exciting about it.
Dont ask me now to compare the micro to the macro cream or give you the details
about the torroid creams harmonic or how wide it is. The difference between torroids
and some of best American made iron is substantial, and you should own at least a pair of
Let me tell you the bad news: these are big round mothers and probably
cant be fitted to your existing amplifier which means you have to build a new
chassis to accommodate them.
Are torroid OPTs the answer to staying refined while using those higher current
DHTs? Are torroids the secret of getting more of those push/pull aural matrix benefits
without push/pulls aural discombobularities? And what happens when we use the 2A3,
and 45 with torroid OPTs? MY ANSWER IS THAT THESE ARE TRULY SIGNIFICANT ACHIEVEMENTS.
And what about REINVENTING PUSH/PULL? What about a push/pull 300B
amplifier with torroid OPTs? I dont know yet!
How do these compare in quality to the new SET OPT designs that I have received?
I prefer the Plitrons.
Are they as good as the the Japanese Masterpieces? They are very different. They
are more alive, bombastic, full of musical juice. They are not as refined harmonically,
and they dont have that magical inter note silence, but they do a magnificent dance.
They make the Western Electric 300Bs come to life, in a way that no other SET OPT has
I have asked Howard Gladstone, President of Plitron and Menno to put together a
new understandable information package about their torroid OPTs and that will
be available soon, so get on the waiting list.
For more information contact Plitron at their email address:
Web site: www.plitron.com