so, i had this idea......

[AKHeathen]

so, i've been thinking about this amp output design, and wondering if it's been done before. the main thing involved is using a torroid off the output transistors, and looping back. any info appreciated.

[Perry Babin]

Tube amps and many of the old EQ/boosters used transformers as the output stage.

[AKHeathen]

how were they used? to convert low voltage to high? high to low? i wasn't sure, but i've seen torroids on a couple newer mono amps, but i assumed they were low noise chokes.

[Perry Babin]

In tube amps, they reduce the voltage and increase the current (tubes aren't capable of passing much current). In the EQ/boosters, they did the opposite. The following is from an amp like they used in the EQ/boosters.
http://www.bcae1.com/temp/majesticma200hd01.gif

[AKHeathen]

ah, yes, i see. kind of the same thing i was thinking. actually thinking on applying it to a class d output to run something like the irf b31n20d fets up close to the 200v and a matching a p-channel through a torroid and rectifiers to boost the current at 100vac output on the other side. essentially, would run 400vac to a high current capable 100v channel.... aand thank you

[Perry Babin]

I think the Kicker Warhorse is a class D variation that has transformers on the output but I've never seen a diagram or worked on one. If I'm not mistaken (I may well be), there are no output transistors, the power supply FETs serve to drive the transformer and the output of the transformers is modulated to produce the audio signal.

[AKHeathen]

oh, so single stage, then? large 12v stage driving high current through the transformer to high voltage? never thought about that...

[Perry Babin]

I don't know. A few years ago, I built something similar that used two transformers. One for positive voltage and one for negative. The power supplies were switched on and off depending on whether the output was positive or negative. I never refined it but it worked. If they're using a single supply, they may use FETs to select positive or negative output voltage.

[AKHeathen]

hmm, i would like to try this on a real simple scale, no mosfets, or anything else, just a simple power supply section, drivers, etc, possibly with tip 35/36c outputs which i have on hand, and run it to 90-100v per side in the 500w range and see how it acts. then, tackle something bigger in class d. off-hand, do you remember if there is a genaric home-made class-d driver card completed for me to build? iirc, somone was trying to map and make one, but not sure if it was finished. would be nice if i could find a simple switching ps driver i could build, too

[Perry Babin]

I don't know of any driver boards. I started to make both types of driver boards but after the overwhelming lack of interest in the power supply boards that I had, I didn't think it would be worth the effort.