Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki 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

Best use of S-265 opt?
Best use of S-265 opt?
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 8th November 2007, 02:29 AM   #1
Don Ericksen is offline Don Ericksen  United States
diyAudio Member
Join Date: Nov 2007
Default Best use of S-265 opt?

Recently I was given a pair of S-265-Q replica transformers that a friend had ordered and decided against using. These are the old Peerles transformers that were used in US versions of the Williamson amplifier. It can be used as a 10K unit with 50% screen taps or a 2K5 unit. They weigh over ten pounds apiece and are good supposedly for about 30 watts apiece.

The Williamson is said to not be unconditionally stable and uses cathode bias. I want an amp that I can use with Quad electrostats as well as other speakers (Williamsons supposedly are a poor choice with these). Can I just use, say, the various ST70 upgrade boards to drive these instead of the Williamson circuit? Or is there some thing about the Williamson fromnt end and driver that makes it work with this high plate load for the output tubes?

If I use it as a 2500 0hm transformer by paralleling the primaries, is this workable with some triode tube for reasonable power?

Finally, is there a reason these can't be used in a unity coupled type circuit with one in the cathode and one in the plate circuit, like the Mcintosh?
  Reply With Quote
Old 8th November 2007, 09:39 PM   #2
Bandersnatch is offline Bandersnatch  United States
diyAudio Member
Join Date: Jul 2003
Location: Ann Arbor, MI
I also have some modern build S265's. I had them assembled with extra U-L taps in 10% increments from 20% to 40% and deleted the 50% tap and split CT which allowed a parallel connection at 2k5 a-a. I have always used it in the 10k connection. I've built with 807, HY69 and 1269, 1619 and 1624 and finally the 4E27 running nearly 140 mA per leg including the front end stage.

I absolutely love them, and have plans to build more amps with them. It is more of a revelation to discover just how many tubes can be used with the 10k load and still stay Class A. 813's are to be next...

Who wound yours? I got mine from Heyboer for $86 each!

ps. they're rated for 40W and with M6 it is probably colser to 60W.
the Tnuctipun will return
  Reply With Quote


Best use of S-265 opt?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

Forum Jump

New To Site? Need Help?

All times are GMT. The time now is 01:58 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 16.67%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio