[sdiy] OPT Driver Circuit?

[Michael Ruberto]

After reverse engineering the line-amp module from my Toa console some more, 
I can see it's topology is very similar to this:

http://www.tnt-audio.com/clinica/dynamicopamp_e.html

But without the zener regulator. I will use this circuit as a model for my 
replacement module. The main benefit of this design is op-amp choice. I can 
use any device here without the +/- 22V requirement. Where I am coming into 
some confusion though is with the OPT driver. Some designs just connect 
directly to the primary or with a 10 Ohm resistor to the primary. Others use 
a very high value bipolar electrolytic cap. Then there's the load isolator 
method which is explained here:

http://waltjung.org/PDFs/ADI_2002_Seminar_Ch6_Audio_Drivers_I.pdf

More info on the load isolator is available from the Jensen website.

So which is the best (most practical) driver for a single-ended transformer 
coupled output?

I've never worked with line OPTs before so any wisdom will be very helpful.

Thanks

M. A. Ruberto

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