Hi janneman
This is not supposed to be Active Sound Cancellation but active control of the generated sound versus the input signal !!
Regards
Charles
At 40 k$ a pair they are quite a bargain compared to some highend speaker/amp combinations 😉
This is not supposed to be Active Sound Cancellation but active control of the generated sound versus the input signal !!
Regards
Charles
At 40 k$ a pair they are quite a bargain compared to some highend speaker/amp combinations 😉
Hey Guys,
"Damping Factor" is a way of putting a number on a very dynamic characteristic of an amplifier. The output impedance of an amp is not purely resistive. It is a complex function that has a phase angle and amplitude that varies from instant to instant. The inductive reactance of the drivers voice coil moving through the magnetic gap is also a complex function with phase and amplitude. Energy from the driver will be disipated in the the resistive component of this complex impedance, this is true. But, this is not the only way that the amp will damp the motion of the drivers cone. The amp will absorb and store energy from the driver and use it in the next instant of time depending on the phase and amplitude (which can be negative) relationship between the Rg and the back EMF of the driver.
Rodd Yamashita
P.S. Sound travels 1in. in ~0.1ms, not 1ms.
"Damping Factor" is a way of putting a number on a very dynamic characteristic of an amplifier. The output impedance of an amp is not purely resistive. It is a complex function that has a phase angle and amplitude that varies from instant to instant. The inductive reactance of the drivers voice coil moving through the magnetic gap is also a complex function with phase and amplitude. Energy from the driver will be disipated in the the resistive component of this complex impedance, this is true. But, this is not the only way that the amp will damp the motion of the drivers cone. The amp will absorb and store energy from the driver and use it in the next instant of time depending on the phase and amplitude (which can be negative) relationship between the Rg and the back EMF of the driver.
Rodd Yamashita
P.S. Sound travels 1in. in ~0.1ms, not 1ms.
roddyama said:
Yes, I stand corrected.
Hey Rodd, this is an interesting concept. Have to think about that one. I can see that the energy could be stored, but I'm not sure about the re-use bit.
Cheers, Jan Didden
Jan,
The output impedance (Rg) is the Thevenin equivlent impedance of the amp looking back into the speaker terminals. What your seeing at any point in time is the sum of all the components (active or passive) that in some way affect the VI and phase at those output terminals.
In the same way, you can take any two points in the amp and the VI and phase across those two points will be dynamic, changing from instant to instant. As an example, the PS caps are constantly being charged and discharged changing the DC buss voltage. Depending on the topology of the amp, the current produced by the back EMF of the driver can go to bring the PS cap voltage back toward the DC supply value. This extra voltage can be used in the next instant because the out of phase feedback loop has just caught up with the VI conditions at the output terminals and are changing the voltage at the bases of the output devices.
Because Rg is so complex, and depends on the design of the amp in question, the damping presented to the driver is not just a function of "Damping Factor", as Mr. Pass points out in his post.
Hope that helps clear thing up.
Rodd Yamashita
The output impedance (Rg) is the Thevenin equivlent impedance of the amp looking back into the speaker terminals. What your seeing at any point in time is the sum of all the components (active or passive) that in some way affect the VI and phase at those output terminals.
In the same way, you can take any two points in the amp and the VI and phase across those two points will be dynamic, changing from instant to instant. As an example, the PS caps are constantly being charged and discharged changing the DC buss voltage. Depending on the topology of the amp, the current produced by the back EMF of the driver can go to bring the PS cap voltage back toward the DC supply value. This extra voltage can be used in the next instant because the out of phase feedback loop has just caught up with the VI conditions at the output terminals and are changing the voltage at the bases of the output devices.
Because Rg is so complex, and depends on the design of the amp in question, the damping presented to the driver is not just a function of "Damping Factor", as Mr. Pass points out in his post.
Hope that helps clear thing up.
Rodd Yamashita
ZZZZZZZZ.....
Huh? What? Somebody mention my name?
I refer you to my patent for acoustic cancellation circuit
# 4,899,387, also known as the Phantom Acoustics Shadow.
On the original topic, there are some fairly easy techniques
for creating a negative impedance on the output of
an amplifier, so that the "damping factor" exceeds
infinity. This amounts to motional feedback, where the
amplifier actively mounts opposition to back EMF, reducing
the apparent series impedance of the amp/cable/speaker
loop.
This seems to help, but as before, doesn't quite deliver
without the heavier hardware resources.
Huh? What? Somebody mention my name?
I refer you to my patent for acoustic cancellation circuit
# 4,899,387, also known as the Phantom Acoustics Shadow.
On the original topic, there are some fairly easy techniques
for creating a negative impedance on the output of
an amplifier, so that the "damping factor" exceeds
infinity. This amounts to motional feedback, where the
amplifier actively mounts opposition to back EMF, reducing
the apparent series impedance of the amp/cable/speaker
loop.
This seems to help, but as before, doesn't quite deliver
without the heavier hardware resources.
Interesting read.
As I have been developing different coils for my planar headphone
transducers I have observed the bass control increasing as the
amount of turns increases.[thus far]
These things are very sensitive to lf signals at present but the
control is Ok.
Also regarding the need for brakes on big cones I note one approach is to use dual coils,one as a pure generator into a load,
or even an active control.
Seems this damping factor issue has many people quite unsure about its real effect.
This whole business is fairly new to me an quite facinating.
Setmenu🙂
As I have been developing different coils for my planar headphone
transducers I have observed the bass control increasing as the
amount of turns increases.[thus far]
These things are very sensitive to lf signals at present but the
control is Ok.
Also regarding the need for brakes on big cones I note one approach is to use dual coils,one as a pure generator into a load,
or even an active control.
Seems this damping factor issue has many people quite unsure about its real effect.
This whole business is fairly new to me an quite facinating.
Setmenu🙂
Shooting holes
I'm firmly of the opinion that damping factor, as normally quoted is almost irrelevant to the sound.
I've heard many amps with theoretically massive damping factors that sound flabby and soft in the bass, and others that have series resistors in their output (after the feedback tap point) that sound fast, tight and infinitely more musical and punchy.
Constant dynamic output impedance is what I'd aim for, across the widest BW possible.
Andy.
I'm firmly of the opinion that damping factor, as normally quoted is almost irrelevant to the sound.
I've heard many amps with theoretically massive damping factors that sound flabby and soft in the bass, and others that have series resistors in their output (after the feedback tap point) that sound fast, tight and infinitely more musical and punchy.
Constant dynamic output impedance is what I'd aim for, across the widest BW possible.
Andy.
Flabby / tight
For Flabby and unmusical listen to just about any far-eastern amp from the 80's and 90's.
Many of these claimed damping factors of 1000 or so and sounded execrable.
For the other case listen to a Naim power amp. There is a series resistor in the o/p of these that limits the maximum achievable damping factor. I've never heard a tighter, punchier power amp, from any manufacturer.
There's an argument that damping of the loudspeaker is something that should be accomplished within the loudspeaker design itself. If your speakers sound woolly, maybe they are at fault, rather than the amp?
It's always best to sort problems out at source, not later on.
Andy.
For Flabby and unmusical listen to just about any far-eastern amp from the 80's and 90's.
Many of these claimed damping factors of 1000 or so and sounded execrable.
For the other case listen to a Naim power amp. There is a series resistor in the o/p of these that limits the maximum achievable damping factor. I've never heard a tighter, punchier power amp, from any manufacturer.
There's an argument that damping of the loudspeaker is something that should be accomplished within the loudspeaker design itself. If your speakers sound woolly, maybe they are at fault, rather than the amp?
It's always best to sort problems out at source, not later on.
Andy.
My Conclusion.
I have listened to the different speakers on Damping Factors.
As this is for me a secondary issue,
I can not say I have more than very fast read over the texts.
I have however not found reason to change my first
Opening Statement. Not the basic message expressed.
So I quote this:
Damping Factor;
nothing to pay any greater notice
Damping factor is something I never
understood either.
A welldesigned amplifier doesn't have to worry
about damp factor.
As most expressions is this a "market slogan"
mostly used to get you into A BUY!
gro
I have listened to the different speakers on Damping Factors.
As this is for me a secondary issue,
I can not say I have more than very fast read over the texts.
I have however not found reason to change my first
Opening Statement. Not the basic message expressed.
So I quote this:
Damping Factor;
nothing to pay any greater notice
Damping factor is something I never
understood either.
A welldesigned amplifier doesn't have to worry
about damp factor.
As most expressions is this a "market slogan"
mostly used to get you into A BUY!
gro
fotenote
for my view on other things that can relate
to similar subjects,
see my views presented in my posts
in this thread
and in all my posting
might be WORTH
while to study
humbly
gro
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so i agromaan from the icecold north
WELCOME, REALLY welcome 😛
japanese indians(red or black) argentinians
israelis chinese scandinavians
English Gentlemen ........
not to mention my african friends
living in africa
or elsewhere
Do not care aboot tham yankeemaan, Jamaicans!
serbians
run out of space
for my view on other things that can relate
to similar subjects,
see my views presented in my posts
in this thread
and in all my posting
might be WORTH
while to study
humbly
gro
* is written in a simple language
*I do not care aboot them yankees
so i agromaan from the icecold north
WELCOME, REALLY welcome 😛
japanese indians(red or black) argentinians
israelis chinese scandinavians
English Gentlemen ........
not to mention my african friends
living in africa
or elsewhere
Do not care aboot tham yankeemaan, Jamaicans!
serbians
run out of space
PS. My homepage.DS
http://www.geocities.com/gromanswe/
do not tell so many!
my server may Crash!
lot of peoples on our world
http://www.geocities.com/gromanswe/
do not tell so many!
my server may Crash!
lot of peoples on our world
Thanks for visiting my website.
Sorry, abobut the bad function, at geocities,
but it is a free webspace.
Limited bandwidth--
So you have to be patient--
wait some hours
or days
And things will have calmed down.
Thanks again! people
groman
webmaster at gromanaudio@swipnet.se
Sorry, abobut the bad function, at geocities,
but it is a free webspace.
Limited bandwidth--
So you have to be patient--
wait some hours
or days
And things will have calmed down.
Thanks again! people
groman
webmaster at gromanaudio@swipnet.se
You are even posting the same thing twice
What he hell does this blather have to do with damping factor?
What he hell does this blather have to do with damping factor?
interesting implication for class A
Well, IF a super high damping factor is not that important, bridge tied lead (BTL) class A deserves another consideration.
One could stay differential all the way from the DAC to the speaker terminals.
Advantages:+ EMI rejection
+ partial distortion cancellation
+ doubled efficiency in class A mode!!!
+ halved supply voltages for same power
Disadvanges:
- halved damping factor
- higher parts count
Well, IF a super high damping factor is not that important, bridge tied lead (BTL) class A deserves another consideration.
One could stay differential all the way from the DAC to the speaker terminals.
Advantages:+ EMI rejection
+ partial distortion cancellation
+ doubled efficiency in class A mode!!!
+ halved supply voltages for same power
Disadvanges:
- halved damping factor
- higher parts count
Damping factor is a secondary issue like THD or maximum watts and so on.
Its all numbers used to sell.
Who ever has the biggest numbers (or smallest in some cases) sells more.
Don´t even believe the numbers at all, they are usually measured in totaly different ways anyway.
What you have to see is the design and hear the quality of the sound it reproduces.
Its all numbers used to sell.
Who ever has the biggest numbers (or smallest in some cases) sells more.
Don´t even believe the numbers at all, they are usually measured in totaly different ways anyway.
What you have to see is the design and hear the quality of the sound it reproduces.
Re: You are even posting the same thing twice
Yeah, can someone send Groman some Prozac or something.
Eric.
Variac said:
Yeah, can someone send Groman some Prozac or something.
Eric.