Shunt Current Feedback

[Stee]

is important to know that the differential stage introduces emphasis
the correct method to apply the subtraction is the potentiometer

so it takes an inverting amplifier
preferably with high input impedance

is also good solution
take the feedback current
able to equalize the performance of the speaker

this is my configuration happier
provides a dynamic scene (XLR source indispensable)
detailed and intensive

[DF96]

This senses the output current. It will therefore raise the output impedance, which will create an 'interesting' frequency response with almost all speakers (which are usually designed for a low output impedance). For example, you will get a bass boost at the bass resonance. It may sound like a cheap ghetto blaster.

[Ouroboros]

There are some good arguments for driving a speaker unit from a high impedance, made by Malcolm Hawksford among others. I am not wholly convinced though, except for increasing Qts in open-baffle loudspeakers.

[DF96]

But only when the speaker was designed to be driven that way. Most speakers are not. They require electrical damping of their mechanical resonance.

[Stee]

my loudspeakers are unfiltered
I don't know what happens with cross-over

[analog_sa]

Originally Posted by Stee

detailed and intensive

Have you actually built an M-9 clone?

Do you think the input fet buffer will actually work into a dead short?

[DF96]

Originally Posted by stee

my loudspeakers are unfiltered
I don't know what happens with cross-over

Not a matter of filtering or crossovers, but driver and cabinet design. What controls the resonances, electrical or mechanical damping?

[Stee]

actually there is a problem with the resonance
the system oscillates in the radio frequency
when the gain control is very close to returning from shunt

I have 4 pieces of M9 with Motorola power Bjt
but I wanted to edit an A100
the model that was born before
http://www.diygene.com/schemas/a-100sch.pdf

I deleted two input resistances and OP-Amp
to bring the next sequence M9
The PSU is made with 4X12V batteries with relais
and 2 switching PSU 24V

I have never heard better
a connection has been lucky
probably because it's rare to have an inverting amplifier

[forr]

Were the amp not inverting, using some precautions, it could give a negative output impedance to lower the electrical damping of a driver.

[analog_sa]

Originally Posted by Stee

I have never heard better

I don't doubt this for a sec. Still, can you say into what impedance is the input buffer working? What kind of distortion can you expect from it alone?