OPT with cathode feedback

[tinitus]

hey, I remember a thread with members debating this
but can't find it

and that noone produce those trafos anymore

well, Amplimo makes them now
and holds the patent too

if some could link to that thread, I will remove this one

[Wavebourn]

You jay use an ordinary transformer with 4 and 16 Ohm secondaries for push-pull cathode feedback.
For SE cathode feedback any secondary may be used.

[Eli Duttman]

Cathode feedback windings are NOT new. Whatever patent Amplimo holds is not on that concept.

Amplimo and Plitron (Canada) are "joined at the hip". Plitron builds Vanderveen designed toroidal trafos. Descriptions of Plitron's tube O/P trafos, including those with CFB windings, can be found here

[LinuksGuru]

Its really not new, I have seen cathode feedback design in Russian magazine published back in 1958.

Vintage amps like Sansui AU-111 and Quad II are examples of cathode feedback. McIntosh unity coupled is actually a 50% cathode feedback (invented in 1936).

Below you can see draft assembly of PP amp with CFB trafos of my own design

[tinitus]

great, thanks

magic word, cathode feedback

hope you don't I 'corrected' the thread title

[tinitus]

how about this one ?

[tinitus]

oh, and with the 'desired' UL tap for driver tube
suddenly figured that out, after long osmosis
maybe

not sure about specs on trafos

well, lots of

[tinitus]

hmm, maybe anode phase splitter choke for driver tube

and 'added' trafo for cathode and garter bias
due to current, sutrely not an interstage
but how about a toroid power trafo
not a CT, but double symmetric windings
though all primary, wouldnt they also work ok as 2x primary and 2x secondary

[tinitus]

interesting Crowhurst amp

original DIY 'kit' from 1957-1960
curcuit and setup explained in detail

http://www.audioxpress.com/magsdirx/...0crowhurst.pdf

[smoking-amp]

Or just use a circlotron output stage. Two OTs for the Twin versus two power supplies for the Circlo.