TORROID OUTPUT TRANSFORMERS
My plan to knock the socks off of the audio industry in the late 1970s was clear and, I thought, a guarantee of success: I was going to manufacture my own version of a Marantz 8B-push/pull (2) EL 34 in triode mode, with a constant current diff amp driver/phase splitter, regulated power supplies, and the killer/diller was...... the torroid output transformers.
At the time, one of my prized possession was a Gotham Audio (Neuman) torroid output transformer tube cutting head amplifier, and I had top secret information about David Haflers ultimate weapon...A Dynaco MK IV with torroid output transformers...that he didnt make because he switched to transistors.
I was working with Avel-Lindberg to design the transformers and then Julius Futterman appeared in my life and you know the rest of the story.
When you read the fall issue of PF you will discover my deep exploration of Tamura transformers (Japan), and my comments to the effect that Americans are catching up with their Japanese bros in terms of caring about output transformer quality. And this is a good thing because paralleling the explosion of tube design creativity is an explosion of output transformer design creativity. While I have been noticing, for a number of year, Plitron Manufacturing advertisements in Glass Audio, I did not notice one tube amp company using torroid output transformers, and wondered why.
I emailed the brotherhood of thermionic techno-shamans all over the world, and in America, and asked if any had any experience using torroids. Not one had any experience, though they too were curious.
Brad Jolly of Plitron Manufacturing, the company that produces these torroids put me into contact with Menno van der veen, the designer of these rare devices, and he sent me a package of the books he wrote about his designs: Specialist Range Lab Report, and, Transformers and Tubes in Power Amplifiers.
As is the usual case Menno has taken push/pull design to a new dimension...according to him. He claims that torroids, the way he designs them, and the way Plitron manufactures them, produces a much higher quality transformer with a much wider bandwidth, that also offers a range of possibility with feedback loops that are unavailable in normal push/pull amplifiers.
Menno is also a tricky devil because he has also designed a torroid single-ended output transformer that he claims improves the quality of these transformer, meaning wider bandwidth, and lower distortion.
Those of you who love the thermionic arts, especially the push/pullphiles should get Mennos books and read them.
But let me remind you again...I am not endorsing these transformers...I have never heard them used in an amplifier, and until that happens, this is nothing more than a promise of expanding the thermionic envelop. I hope Menno and Plitron do the right thing and produces some amplifiers that demonstrate the truth of his theories. That would be way cool.
Check the Plitron web site for a description of these books: www.plitron.com (1-800-754-8766)
e-mail Dr. Harvey "Gizmo" Rosenberg: firstname.lastname@example.org
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