Autoformer output stage

[dave slagle]

Hmm...

1/2mm offset might cause me a problm with my lowthers and their 1mm Xmax

don't get me wrong, i really wanted to try this idea SE, but feared the worst so i am quite interested in your results. A multiway speaker would go a long way to making this problem a non-issue.

dave

 

[Fuling]

lowthers and their 1mm Xmax

Ah, I see!

 

[woody]

What about nulling the offset by injecting -300 ma? Wouldn`t
-30 v and a 100 ohm resistor solve this.

 

[Fuling]

I ditched the autoformer idea because of the output DC issues and made myself a pair of "ordinary" OPT´s instead.
These are 500:8 ohms units intended for a PSE amp with 3xPL504.
The 27% CFB windning should give slightly more than 6dB feedback, a little more than in my smaller prototype (which sounded darn good).

Primary windings are 1100 turns, 300 of them are separated for the CFB and divided into three sections spread out amongst the the three primary sections.
Secondarys are 136 turns, two sections. Core size= EI96, which is 85VA.

 

[Fuling]

And here´s how the windings are interleaved.
Text is in swedish, but it´s mostly numbers anyway.