In article ,
Chuck wrote:
On Mon, 11 Jun 2018 06:56:43 -0700 (PDT), wrote:
Those darn things would break into spurious oscillation driving a
resistive load. I came up with a mod that made them stable enough that
a local rock band used them as their main amps.
so what was the mod?
I did these mods back in the 1970s and then I had a near photographic
memory so I didn't document it. It consisted of installing pico value
caps in various locations. I can't remeber the locations or values of
the caps.
I think there's only one global feedback loop and then local feedback on
the finals, so there are a limited number of poles in the system for you
to move around. Should not be too hard to figure out how to make it stable
especially with modern test equipment.
BUT.... you'll never fix the horrible crossover distortion on those things.
Well, maybe you could by redesigning the output stage, but then you might
as well just get a good amp.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."