[J-Pak]

Anyone have any preferences for OPTs? I am looking for a push-pull OPT to be used for 300B with about 6k primary. Lundahl is at the top of my list right now since it looks like they measure well and are reasonably priced.

[Freo-1]

I would check out Edcor.  They are well made, and reasonably priced.  I recently bought a pair of 60 W 6.6K output transformers for a push pull 55 WPC amp that uses 1625 output tubes.  They sound GREAT!!

Also ordered custom made power transformers with four output taps to run the amp.  The amp is perhaps the quietest tube amp I've ever owned, even quieter than most sand amps.
 

 

[J-Pak]

Those are great looking amps!

I'm also interested in seeing measurements for any OPTs if you guys have links. I haven't found much out there.

[FullRangeMan]

The good: some tests from SAC-Thailand:
http://www.sacthailand.com/Transformer_TestOutput.html

Various brands comparative test:
http://www.sacthailand.com/Transformer_SilkWinding.html

Specs/Prices:
http://www.sacthailand.com/Transformer_Output.html

Some theory:
http://www.turneraudio.com.au/output-trans-theory.htm

http://www.turneraudio.com.au/education+diy.html

[FullRangeMan]

The bad, (maybe manufactured for guitar).
Bad winding: E I core + thick wire and spaced turns

http://diy-rbt3.tripod.com/dcts/index.album/enrolamento-primario?i=1
Final result: crap (200Hz).

http://diy-rbt3.tripod.com/dcts/index.album/enrolamento-primario?i=1
Below a proper wind from other manufacturer intend for audio use:

[J-Pak]

Thanks very much FULLRANGEMAN!

Gary Pimm's transformer measurements (unfortunately no OPTs): http://www.pimmlabs.com/web/transfomer_measurements.htm