Hello,
I have some informations about the Damping factor but i still need more.
If i have 6 Class d Amps and a pair of 3 way speaker. I use active crossover in the system. For the bass, i prefer the High DF what the D-class amp can produce.
But if i like to make the midrange and the treble make more softer. How can i make it?
Can i attach a stepped attenuator after the amp and before the midrange driver? Can i manually change the Damping factor this way?
I am not an electronic expert yet, i am kind of a student.
Please give me advice how can i reduce damping factor for the midrange and the treble from 1000 to 20-30 or lower? And i like to make it on a switcheable way.
Thanks
I have some informations about the Damping factor but i still need more.
If i have 6 Class d Amps and a pair of 3 way speaker. I use active crossover in the system. For the bass, i prefer the High DF what the D-class amp can produce.
But if i like to make the midrange and the treble make more softer. How can i make it?
Can i attach a stepped attenuator after the amp and before the midrange driver? Can i manually change the Damping factor this way?
I am not an electronic expert yet, i am kind of a student.
Please give me advice how can i reduce damping factor for the midrange and the treble from 1000 to 20-30 or lower? And i like to make it on a switcheable way.
Thanks
Hi,
A variable resistor in series with the driver, or more
advanced, modifying the amplifiers feedback loop,
will change the effective damping factor.
It won't make it any softer though, in any real sense.
The mid and treble will peak up at at the resonant
Fs and any inductance rise will raise levels.
rgds, sreten.
Also note class D treble flatness depends on impedance matching.
A series resistor of 0.27R/0.33R will reduce DF to 20 to 30.
A variable resistor in series with the driver, or more
advanced, modifying the amplifiers feedback loop,
will change the effective damping factor.
It won't make it any softer though, in any real sense.
The mid and treble will peak up at at the resonant
Fs and any inductance rise will raise levels.
rgds, sreten.
Also note class D treble flatness depends on impedance matching.
A series resistor of 0.27R/0.33R will reduce DF to 20 to 30.
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It is class D. Either the transistor top and bottom is on or off. The time they are held on or off gives the audio output through the choke to the loud speaker. It is not a class B or A.
What is the point in reducing the damping factor from 1000 to 20~30 when the voice coil of the speaker has a resistance of several ohms?
Rayma, yes i doesn't speak about the loudness of the channels, just the harsness,
and "edged" sound.
and "edged" sound.
Is there serious difference to use L-pads or this:
http://diyaudioprojects.com/Misc/DIY-Stepped-Attenuator/Stereo-Stepped-Attenuator.jpg
Please be patient with me. 🙂
I read in a lot of article that a speaker good for Jazz, but not good for rock. I like to make switcheable the "caracteristic" of my system
to make the midrange smoother, or sharper. Depending the music i listening.
http://diyaudioprojects.com/Misc/DIY-Stepped-Attenuator/Stereo-Stepped-Attenuator.jpg
Please be patient with me. 🙂
I read in a lot of article that a speaker good for Jazz, but not good for rock. I like to make switcheable the "caracteristic" of my system
to make the midrange smoother, or sharper. Depending the music i listening.
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Some information about amps which uses varieable damping control.
Accuphase E-202
A guy wrote the following: "Using it with the E-202 has made a dramatic difference with some speakers, no doubt about it. It also lets you tailor the sound characteristic to change the character of the amp itself quite a bit."
Bogen tube amplifier has variable damping option too.
Accuphase power amp P-250 too
An othe guy wrote it: "The system which changes the dumping factor of amplifier is adopted so that the speaker designed by the Tube amplifier age may also be matched.
It can be possible to choose three, 20 (NORMAL) or more, and 5 (MEDIUM) and 1 (SOFT), in the time of 8-ohm load, and, thereby, sound quality peculiar to tube amplifier can also be enjoyed now. (NB: the bad translation from the Japanese is not mine!) "
VTL Signature monoblock tube amp:
"
1. LOW -- Lowest damping factor, good loudspeaker control, most natural sound.
2. MED -- Better loudspeaker control, with some impact on sound quality.
3. HI -- Best loudspeaker control, with a little more impact on sound quality, but on speakers that need the control the sonic improvement is clear.
4. MAX -- Maximum damping factor, but sonic impact is noticeable"
SES RM-245 amplifier
http://www.ramlabs-musicreference.com/SES_Series.html
"Damping factor: The 245 and 245.1 have adjustable damping from 1 to 8 selected by the rotary switch in the center. All our amps have deep, well defined, solid bass with good pitch resolution."
"Acrosound Ultralinear IIs have adjustable damping. I believe that Peavey Classic 50/50 EL84 amps have variable damping but they call it something else."
Technics SE-9600
Accuphase P-20 poweramp
Accuphase E-202
A guy wrote the following: "Using it with the E-202 has made a dramatic difference with some speakers, no doubt about it. It also lets you tailor the sound characteristic to change the character of the amp itself quite a bit."
Bogen tube amplifier has variable damping option too.
Accuphase power amp P-250 too
An othe guy wrote it: "The system which changes the dumping factor of amplifier is adopted so that the speaker designed by the Tube amplifier age may also be matched.
It can be possible to choose three, 20 (NORMAL) or more, and 5 (MEDIUM) and 1 (SOFT), in the time of 8-ohm load, and, thereby, sound quality peculiar to tube amplifier can also be enjoyed now. (NB: the bad translation from the Japanese is not mine!) "
VTL Signature monoblock tube amp:
"
1. LOW -- Lowest damping factor, good loudspeaker control, most natural sound.
2. MED -- Better loudspeaker control, with some impact on sound quality.
3. HI -- Best loudspeaker control, with a little more impact on sound quality, but on speakers that need the control the sonic improvement is clear.
4. MAX -- Maximum damping factor, but sonic impact is noticeable"
SES RM-245 amplifier
http://www.ramlabs-musicreference.com/SES_Series.html
"Damping factor: The 245 and 245.1 have adjustable damping from 1 to 8 selected by the rotary switch in the center. All our amps have deep, well defined, solid bass with good pitch resolution."
"Acrosound Ultralinear IIs have adjustable damping. I believe that Peavey Classic 50/50 EL84 amps have variable damping but they call it something else."
Technics SE-9600
Accuphase P-20 poweramp
In the special case of full range speaker and highly
damped zero impedance amp with perfect cables.
And not saying this case describes any real case.
Any resistance in placed in parallel with that speaker
would be indistinguishable from resistance placed in
parallel with the amplifier.
Any resistance in parallel with zero is zero.
----
Once you add any series resistance, or reduce the
damping factor, or add a crossover: only then may
parallel resistance have an effect.
----
Switching cycles are not limited to simple ON or OFF,
but may include significant periods of Open Resonance
and Closed Freewheeling, especially when zero voltage
switching of one or more edges is a desired objective.
Its not one switch with two simple states, but mutiple
switches all working together, and rarely simultaneous.
Not relevant to audio frequency damping or impedance,
just setting the record straight about switches.
----
As for damping factor, this is not determined by amplifier
class, but by feedback. Class D is perfectly capable to play
music open loop, with near infinite output impedance over
the audio frequency range.
As with any class, this impedance may be further reduced
by controlled feedback of less than 90 degrees phase shift.
Achieving actual zero output impedance is impossible due
to rules that define an oscillator, but some amps get close.
Not saying that doing so is always the best approach.
----
Loudspeakers are less affected by mechanical resonance
when driven by a low impedance. Particularly so around Fs.
Loudspeakers without shorting rings are less affected by
roll-off when driven from a high impedance source. The
force delivered at the coil is now same for all frequencies,
but at the full uncorrected mercy of mechanical effects.
That may be OK, since mid and high frequency mechanical
effects may occur far from the coil and beyond the 90 deg
of phase shift we could attempt to control.
An amplifier with damping that varies over frequency, to
give damping only for frequencies where correction of a
mechanical problem is actually possible, might be a very
interesting project.
----
Feedback loops affect not only damping, but also gain.
Would require equalization if damping were variable.
Equalization shifts phase of arrival, and not entirely sure
weather that might correct or aggrivate the final result.
damped zero impedance amp with perfect cables.
And not saying this case describes any real case.
Any resistance in placed in parallel with that speaker
would be indistinguishable from resistance placed in
parallel with the amplifier.
Any resistance in parallel with zero is zero.
----
Once you add any series resistance, or reduce the
damping factor, or add a crossover: only then may
parallel resistance have an effect.
----
Switching cycles are not limited to simple ON or OFF,
but may include significant periods of Open Resonance
and Closed Freewheeling, especially when zero voltage
switching of one or more edges is a desired objective.
Its not one switch with two simple states, but mutiple
switches all working together, and rarely simultaneous.
Not relevant to audio frequency damping or impedance,
just setting the record straight about switches.
----
As for damping factor, this is not determined by amplifier
class, but by feedback. Class D is perfectly capable to play
music open loop, with near infinite output impedance over
the audio frequency range.
As with any class, this impedance may be further reduced
by controlled feedback of less than 90 degrees phase shift.
Achieving actual zero output impedance is impossible due
to rules that define an oscillator, but some amps get close.
Not saying that doing so is always the best approach.
----
Loudspeakers are less affected by mechanical resonance
when driven by a low impedance. Particularly so around Fs.
Loudspeakers without shorting rings are less affected by
roll-off when driven from a high impedance source. The
force delivered at the coil is now same for all frequencies,
but at the full uncorrected mercy of mechanical effects.
That may be OK, since mid and high frequency mechanical
effects may occur far from the coil and beyond the 90 deg
of phase shift we could attempt to control.
An amplifier with damping that varies over frequency, to
give damping only for frequencies where correction of a
mechanical problem is actually possible, might be a very
interesting project.
----
Feedback loops affect not only damping, but also gain.
Would require equalization if damping were variable.
Equalization shifts phase of arrival, and not entirely sure
weather that might correct or aggrivate the final result.
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Thanks for the lot of information Kenpeter.
Yes, you just defined my goal: to
give damping only for frequencies where correction of a
mechanical problem is actually possible, might be a very
interesting project.
This is why i go active, it is easier to correct the system weak points
if i separately drive the drivers.
Have you an exact idea how can i solve this problem.
All i want/need is to make varieable the output impedance of an amplifier.
If it is possible i like to make it the best soundng way. / Or the easier way. 🙂
Yes, you just defined my goal: to
give damping only for frequencies where correction of a
mechanical problem is actually possible, might be a very
interesting project.
This is why i go active, it is easier to correct the system weak points
if i separately drive the drivers.
Have you an exact idea how can i solve this problem.
All i want/need is to make varieable the output impedance of an amplifier.
If it is possible i like to make it the best soundng way. / Or the easier way. 🙂
A simple series resistor, a few tenths of an ohm or so, maybe 5W rated, in line with the driver will do what you ask. Higher resistance-->less damping.
"Tubelike" is variable bandwidth that depends on transformer saturation.
I don't think you will get there with just a series resistor, and will make
the low end performance very under-damped.
You might try a ((low pass iron core choke in parallel with a resistor) in
series with your loudspeaker). But will have bass boost at that pole, you
might excuse this imperfection as a "baffle step correction".
I don't think you will get there with just a series resistor, and will make
the low end performance very under-damped.
You might try a ((low pass iron core choke in parallel with a resistor) in
series with your loudspeaker). But will have bass boost at that pole, you
might excuse this imperfection as a "baffle step correction".
Forget I said iron. A core'd choke is going to pass highs when saturated,
completely opposite what a "tubelike" output transformer does... An air
core choke (that cannot saturate) in parallel with a resistor (sometimes
wound on the ceramic body of that resistor) used to be a fairly common
feature of solid state audio amps. Something like that would be OK.
Still valid that you might hide the transition from overdamped to not-so-
damped and slight attenuation by the resistor at a frequency where you
may need baffle step Eq anyway. Kill two birds with one filter...
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