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Old 23rd August 2011, 06:40 AM   #1
Stee is offline Stee  Italy
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Default Shunt Current Feedback

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
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Last edited by Stee; 23rd August 2011 at 06:43 AM.
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Old 23rd August 2011, 10:15 AM   #2
DF96 is offline DF96  England
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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.
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Old 23rd August 2011, 10:22 AM   #3
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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.
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Old 23rd August 2011, 11:07 AM   #4
DF96 is offline DF96  England
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But only when the speaker was designed to be driven that way. Most speakers are not. They require electrical damping of their mechanical resonance.
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Old 23rd August 2011, 12:43 PM   #5
Stee is offline Stee  Italy
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Default yes of course

my loudspeakers are unfiltered
I don't know what happens with cross-over
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Old 23rd August 2011, 12:51 PM   #6
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Quote:
Originally Posted by Stee View Post
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?

Last edited by analog_sa; 23rd August 2011 at 12:56 PM.
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Old 23rd August 2011, 01:58 PM   #7
DF96 is offline DF96  England
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Quote:
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?
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Old 23rd August 2011, 05:47 PM   #8
Stee is offline Stee  Italy
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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
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Old 23rd August 2011, 06:00 PM   #9
forr is offline forr  France
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Were the amp not inverting, using some precautions, it could give a negative output impedance to lower the electrical damping of a driver.
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Old 23rd August 2011, 06:25 PM   #10
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Quote:
Originally Posted by Stee View Post
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?
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