I was sure I had heard of people building single ended push pull (or series push pull) power amps but I can't seem to locate any examples. I presume they would be either OTL or parafeed. Was I dreaming?
mike
mike
Single ended push-pull can be OTL such as the futterman or totem design.
I’m assuming single ended input and single ended ouput are possible.
I’m assuming single ended input and single ended ouput are possible.
The relatively new Western Electric 91E amplifier is a SEPP (totem pole) design. You can read John Broskie's Article about it.
I also remember years ago the Japanese were building some that did use a regular push pull OPT but was not a para feed design. I saw it in one of the popular "Mu Sen To Zi Ken" (or MJ) magazines from the late 80s or early 90s.
I also remember years ago the Japanese were building some that did use a regular push pull OPT but was not a para feed design. I saw it in one of the popular "Mu Sen To Zi Ken" (or MJ) magazines from the late 80s or early 90s.
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Philips produced them in their thousands. Employed an 800 ohm impedance speaker, no opt.
https://www.diyaudio.com/community/threads/sepp-for-philips-800-ohm-loudspeaker.10904/
https://www.diyaudio.com/community/threads/sepp-for-philips-800-ohm-loudspeaker.10904/
https://audioxpress.com/article/The-SPP-Amplifier
I like the trick with the PT as dual choke. Used it myself in an OTL and in a power SRPP. I used the Triad FP230 series, with one secondary and one primary in series for each leg, ensuring equal DC resistance. As the four windings are all isolated from each other in different chambers, no problems with highish delta V over the windings.
I like the trick with the PT as dual choke. Used it myself in an OTL and in a power SRPP. I used the Triad FP230 series, with one secondary and one primary in series for each leg, ensuring equal DC resistance. As the four windings are all isolated from each other in different chambers, no problems with highish delta V over the windings.
Hi ErikdeBest,
Interesting, I drew what I think you are describing, so you wired a secondary and primary in +/- series, then wired each of those pairs "back to back"? Here is a photo, do my polarities and wiring look correct? The article did not offer a detailed schematic on how they actually wired the coils to do this.
Hi Windcrest,
This is how I used them. It should be a dual choke with similar DC current, that flow in opposite direction, therefore cancelling, just like in a PP OPT.
Here is the OTL where I use this. Started unstable, but is now running fine in the main system.
https://www.diyaudio.com/community/threads/beam-power-pentode-otl.391888/
I also tested this Trafo as a center tapped PP audio choke (same schema, connecting pin 4 and 6 to B+, 1 and 7 to the plates) obtaining frequency response beyound 20kHz, so want to try that in an actual amp, once.
This is how I used them. It should be a dual choke with similar DC current, that flow in opposite direction, therefore cancelling, just like in a PP OPT.
Here is the OTL where I use this. Started unstable, but is now running fine in the main system.
https://www.diyaudio.com/community/threads/beam-power-pentode-otl.391888/
I also tested this Trafo as a center tapped PP audio choke (same schema, connecting pin 4 and 6 to B+, 1 and 7 to the plates) obtaining frequency response beyound 20kHz, so want to try that in an actual amp, once.
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