Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders.

---

[ Follow Ups ] [ Post Followup ] Thread: [ Display  All  Email ] [ Tube DIY Asylum ]

---

[ Alert Moderator ]

---

OPT Not Always the Case

Posted by Super_BQ (A) on October 6, 2007 at 17:49:41

In Reply to: RE: DIY 300b SET 10 Watt AMP posted by Eli Duttman on October 6, 2007 at 15:03:18:

Though I 100% agree that the quality of the output transformer is paramount (in SET design), do not get sucked into the belief that only good transformers come from western known manufactuers.

In a recent post of mine, I tested the $800 Plitron output transformer 3.5K for SET design against a rare chinese Zuoshi brand OPT. To my surprise the Plitron was NOT EVEN CLOSE to the quality sound of the Zuoshi. I'll give some credit to the Plitron that the sound may be suitable for many, to my ears, the sound was very analytical - removed all the sonic character of the 300B.

The Zuoshi was exotic alone. Weighing over 6.5kg each, it came potted in a (mu-metal? like square case) with OIL filled inside. 3.3Kohm primary. I won't mention prices on the Zuoshi but let's say that i'm sick of hearing people say China made stuff is rotten. The fact is the more you pay doesn't mean anything on the sound quality you like!

Why the poor performance or sound of the Plitron? I have 2 reason:

1) Toroidal design itself is not ideal for single ended. The idea of making a cut into the toroidal so it mimmicks an air gap of a conventional EI output transformer is not sonically good. After several decades, EI OPT have been the norm and why toroidal outputs are rarely used? Perhaps in practice it doesn't sound good, though many will find the odd high end makes do very well in marketing. "Mr. Vanderveen"

or

2) The quality of Plitron's output transformer is questionable. Just like certain Chinese made iron is questionable regardless of price.

This post is made possible by the generous support of people like you and our sponsors:

Signature Sound

[ Signature Sound Lounge ]

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2025, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---