Talk:Damping factor/Archive 1

message: This is not now accurate becuse to have damping factor, there must be something to damp - like an oscillatory system. No such system is described in the lede para! Therefore Im proposing a merge with the damping article --Light current 22:05, 22 April 2006 (UTC)
thread_title:  Definition/lede 

message: I have a real problem with this statement...
"A large damping factor is no advantage beyond a certain point, probably around 10." This is totally not true... and totally obvious to anyone who works in the professional audio field, as I do.  A large damping factor (100 or greater, preferably 400 - 1000) is highly desirable, and mandatory for quality bass reproduction, given the way that loudspeakers work.  Please read the referenced article from Crown Audio. Anyone who believes a large damping factor is no advantage is confusing the issue of feedback (and possible negative effects of feedback) with damping factor. Tvaughan1 22:33, 21 April 2006 (UTC)
thread_title:  Large Damping Factor is desirable for audio amplifiers 

message: Light Current... please read the "Description of damping factor" article referenced at the bottom of damping factor.  If you understand how a loudspeaker works, and I trust that you do, you will realize that the article is correct (due to mechanical factors... the spring effect of the diaphragm, the mass and inertia of the diaphragm...). Tvaughan1 
: Please sign your posts anon, then I know who Im talking to!--Light current 00:16, 22 April 2006 (UTC)
replies: text: THe article you reference is very badly written and inaccurate. Let me ask you a question: How well damped would a speaker be if the amplifier output could be represented as a pefect S/C. Would it be perfect - or less than perfect. Why?--Light current 03:11, 22 April 2006 (UTC)
thread_title:  Moved from [[User talk:Light current]] 

message: My JBL 2245H 18" subwoofers sound pretty darn good... flat response down to 30 Hz, and good response down to 20Hz.  But they sound horrible if they are driven with an amplifier with a damping factor of 10.  That is why I use a Crown DC-300A Series II.  The manual for this amplifier describes the following... 
"Your amplifier can provide an excellent damping factor of 750 or more from DC to 400 Hz in Dual mode with an 8 ohm load. In contrast, typical damping factors are 50 or lower. Higher damping factors yield lower distortion and greater motion control over the loudspeakers. A common damping factor for commercial applications is between 50 and 100. Higher damping factors may be desirable for live sound, but long cable lengths often limit the highest damping factor that can be achieved practically. (Under these circumstances, Crown’s IQ System® is often used with Crown’s premium Macro-Tech,® Com-Tech® and Reference series amplifiers for easy monitoring and control of units located very near the loudspeakers.) In recording studios and home hi-fi, a damping factor of 500 or more is desirable."
My ears tell me that the Crown Engineers are right, and that the statement "A large damping factor(greater than about 10) is no advantage" is totally incorrect.  I believe the Crown Audio engineers have done their homework, and are an authoritative reference on the subject.  I have worked in professional audio for 19 years.  I have designed, constructed and operated quality assurance studios for record companies and CD manufacturers.  Professional engineers in the recording studio industry and in the sound reinforcement business understand the difference that a high damping factor makes.  It's easy to understand if you use your ears.  It's also easy to understand from a mathmatical and a practical standpoint.  The lower the damping factor, the more you will have unwanted motion on your low frequency (high mass) drivers.  Unwanted motion of the cone means unwanted sound.  Unwanted sound is distortion... it does not represent the originally recorded signal, it is noise.  Arguing that "a large damping factor (greater than 10) is no advantage" is a disservice to those who would reference the article, looking for good advice when choosing an amplifier or building a sound system. Tvaughan1 15:45, 23 April 2006 (UTC)
replies: text: You seem to be missing my point!. Whilst your system may be able to reproduce anything down to sub sonic, most system cant. In these cases, low damping can enhance an inadequate bass response. THats all I'm saying. I cant see your argument against! BTW Youre ears, as are most people's, are unreliable! THats why we use test gear.--Light current 18:38, 23 April 2006 (UTC)
replies: text:  I get the point, you want "one note" bass.  Any bass frequencies all turn into the resonant frequency of the speaker.  It's intermodulation distortion.  Look, my ears have spent years being the reference standard for quality at a major record label.  I'm a musician, and I can hear more than most people can due to years of critical listening.  It's a blessing and a curse (as it is with video, by the way, as I see MPEG compression artifacts like the kid in the 6th sense sees dead people).  The point is, if ANYONE can hear a difference between system A and system B (in a valid, double-blind listening test), then there is a difference, and there must be an explanation.  Audio is an art and a science.  If the artist tells you there is a difference, the scientist better figure out how to explain it, measure it, and deal with it.  As I've pointed out, I've dealt with many situations where recording engineers and audiophiles would tell me there was a problem, and I would conduct tests to debunk the myth... always successfully.  It just seems as if you have never heard a bad sound system with low damping factor.  Why else would you argue that zero damping factor would be not only OK, but preferred?  Find a really cheap DJ with a really cheap sound system, and ask him to crank up the dance music.  Or listen to any teenager's car stereo system with 1000 watt bass drivers.  You'll hear what low damping factor is.  Muddy bass. Tvaughan1 22:44, 23 April 2006 (UTC)
replies: text:  No I dont want "one note" bass. Im suggesting that in a system with restricted bass response, like a small bass cab, or cheapo woofer, lowering the damping factor can give more o/p at the expense of flabbyness. But lots of people like a flabby bass. THis is well known in the bass amp business! Im surprised youve not heard of it! And wher on earth do you get the notion that it causes IM dist?--Light current 04:07, 24 April 2006 (UTC)
thread_title:  DF more critical for larger, more massive loudspeakers 

message: BTW you dont tell us how your 18" JBLs are mounted. Are they in a sealed cab, reflex or TL structure.And why do you need TWO? I think this may have some bearing on DF--Light current 04:25, 24 April 2006 (UTC)
replies: text: They are in a ported enclosure.  Tvaughan1 03:20, 25 April 2006 (UTC)

text: "Flabbyness"?  You concede that a lower damping factor is audible.  Tvaughan1 21:00, 24 April 2006 (UTC)

text: The frequency response of both amplifiers is excellent... flat from 20 to 20,000 Hz.  It's not a factor.  Tvaughan1 16:44, 25 April 2006 (UTC)

text: Unless you are working with elephants (and specially designed speakers), infrasonic or subsonic signals are undesirable, as they will just waste power, distort your audio and possibly burn out your speakers.  The frequency response of even the best subwoofers falls very steeply as you go below 20 Hz (for most speakers it starts to fall off much higher... at 30, 40, or 50 Hz... the vast majority of consumer speaker systems can't reproduce the lowest octave in the human hearing range with any accuracy).  Most audio systems that provide the signal (tuners, pre-amplifiers, CD players, etc.) have high-pass filters to prevent subsonic signals from being passed to the amplifier.  If you suspect that your system doesn't have this (for instance, for a live sound reinforcement system with microphones and a mixing console), amplifier manufacturers such as Crown recommend that you add a high-pass filter to remove subsonic or DC signal components. Tvaughan1 13:14, 26 April 2006 (UTC)
thread_title:  Mounting method and possible effect on DF 

message: Ahh, now you tell us that you have Golden Ears! We used to have someone over here who said he had golden ears. He was blind and his name was Angus something (I think it was McKenzie). He could hear a pin dropping on the moons surface-- but no one else could. It's true that you can train your brain to hear things that others can't. Maybe you can hear differences in DF - that doesnt mean that everyone can. And it means therefore that its generally not important to most people if they can't hear it. I think that's what the article says. If it doesnt - it soon will.--Light current 01:33, 24 April 2006 (UTC)
replies: text: Don't misquote me.  I told you I have good hearing, and I told you that I have some training in music and critical listening.  I told you a little bit about my professional background and job responsibilities.  I think you've hit the nail on the head, however, when you say that maybe I can hear differences in DF that not everyone can... that is almost certainly true.  That doesn't mean that a high damping factor isn't important.  Look, the majority of consumers don't know how audio systems work, and they don't know how to measure their performance (objectively or subjectively).  They don't know how to interpret the manufacturer's specifications.  That doesn't mean that they wouldn't benefit from one system versus another.  All things being equal, they would benefit from a system with more accurate sound reproduction.  Some of these consumers may be coming to Wikipedia to look up damping factor.  Let's give them the facts.  Tvaughan1 03:24, 24 April 2006 (UTC)

text: It should be fairly obvious why this setup won't work... you propose changing the volume level along with the damping factor.  Tvaughan1 20:47, 23 April 2006 (UTC)

text: Going from 0 to 10 ohms changes the impedance from 8 to 18 ohms.  That's more than a fraction of a dB.  The point is, if the volume changes, it kills the validity of a double-blind listening test, as the subject could easily hear the volume difference and reliably identify setup A from setup B when presented with 10 random samples.  You wouldn't know if the subject was hearing the difference in damping factor or the difference in volume. Tvaughan1 22:33, 23 April 2006 (UTC)
thread_title:  Personal Experience / Expertise 

message: For Damping factors between 50 and 2000 there is less than 1ms diff in decay time. There is 1 ms diff between DF of 20 and DF of 50.
Can TV1 hear 1ms difference?
--Light current 22:27, 23 April 2006 (UTC)
replies: text: Please sign your posts.  This is an interesting reference... I added it to damping factor.  Did you read the rest of the article?  The tables in this article were made using certain assumptions (speaker with a Q of 3, etc.).  In any case, the audibility higher damping factors is certainly an open question.  I don't claim to have the ability to hear the difference between a DF of 50 and 2000, nor even 20 and 50.  I'm reasonably sure I could hear the difference between 10 and 100... but I'd have to conduct a valid experiment, and such and experiment would take some careful set-up (especially if you are using a series resistor, which changes the volume, and if compensated by increasing the amplifier's gain it increases the noise... although in most cases by a trivial amount). Tvaughan1 22:20, 23 April 2006 (UTC)
thread_title:  Interesting table from one of the links 

message: * No — Omegatron 01:12, 23 April 2006 (UTC)
thread_title:  Merge 

message: This page is overdue for archiving. As replies and posats have been interleaved somewhat, does anyone want me to put the posts now into logical order unser separate hdgs (refactoring) . Or do you want to leave them in this (rather unsatisfactory) order before archiving? See WP:REFACTOR--Light current 03:38, 24 April 2006 (UTC)
replies: text: It is not.  Leave it until a few weeks after discussion has died down. — Omegatron 13:45, 24 April 2006 (UTC)
replies: text:  What about the page size limit?--Light current 14:43, 24 April 2006 (UTC)
replies: text:  What about it? It's archaic, and only a recommendation. Any decent browser that is less than five years old can handle much more than 32K text. Graham 14:46, 24 April 2006 (UTC)
replies: text:  Yes Ive heard that, and Ive also heard the other argument that pages should not exceed 32k for readability etc. THe policy is uncertain. However, I do beieve that a page longer than 32k can be difficult to navigate and follow esp with multiple respondents.--Light current 15:15, 24 April 2006 (UTC)
thread_title:  Archiving 

message: * fs: 	20 Hz
* Re: 	5.8 ohms
* Qts: 	0.27
* Qms: 	2.2
* Qes: 	0.31
* Vas: 	820 L (29 ft3)
* Sd: 	0.130 m2 (200 in2)
* Xmax: 	9.5 mm (3/8 in)
* Vd: 	1,230 cm3 (75 in3)
* Le: 	1.4 mH
* no (Half space): 	2.1%
* Pe (Max): 	300 W Continuous Sine Wave
--Light current 23:17, 25 April 2006 (UTC)
thread_title:  THIELE - SMALL PARAMETERS: for JBL 2245H 

message: I think Im right in saying that what is required from a low frequency speaker system is critical damping. That is, not underdamping (where you get hangover) or over damping (where the cone just wont move fast enough in response to a step voltage input). Now it is my contention that a speaker is a mechanical system with a mechanical to electrical transformer (the voice coil) attached and this transformer is driven by an amplifier of usually very low output impedance.
=== Transformation analysis ===
Since the mechanical force on the coil, fm is given by:
fM=Bli
and the emf developed by the moving coil is
e= Bl dx/dt
It is therefore evident that:
ZEM = (Bl)^2/ZM
where ZEM is the electrical impedance due to motion, and is termed the 'motional electrical impedance'. The mechanical to electrical transformation ratio for impedances is therefore (Bl)^2 and is determined solely by the voice coil/magnet assembly.
Now in analysing such a system, one may choose to convert the mechanical components (mass, compliance, acoustic resistive or reactive loading etc) into electrical components or vice versa by referring the elements to one side or the other of the 'transformer'. It is usually easier to do the former and analyse the performance in the electrical domain. The mechanical/electrical transformer is of course an electric motor/generator. 
The transformation constant (Bl)^2 is a scalar and therefore does not change the phase angle of the impedance when transformed, only its magnitude. Therefore inductive components (masses) transform to inductances, and capacitive (compliances) transform to capacitors, whilst resistors (mechanical dampers) transform to resistors. 
The total electrical impedance seen at the voice coil by the amplifier, Zen, is given by the sum of the damped electrical impedance and the motional electrical impedance ie:
Zen =Ze1 +Zem
Now Zen can be represented as a series combination of R,L and C. The L represents the transformed mass of the cone in the mechanical cct, and the C represents the total transformed compliance of the driver. The R represents the sum of the transformed motional resistance plus the electrical (DC) resistance of the voice coil.
: This analysis appears to be original work.  Wikipedia is not the place to publish original work.  Tvaughan1 00:47, 15 October 2006 (UTC)
replies: text: Yes.  We do.  Across the full frequency range of the speaker.  But the article is about damping factor, so it needs to focus on how you design or evaluate an amplifier (which may have any speaker connected... cheap or well designed... in various configurations (alone, series, parallel), through wires with unknown length or resistance. Tvaughan1 22:38, 26 April 2006 (UTC)
thread_title:  Critical damping 

message: Since the mechanical force on the coil, fm is given by:
fM=Bli
and the emf developed by the moving coil is
e= Bl dx/dt
It is therefore evident that:
ZEM = (Bl)^2/ZM
where ZEM is the electrical impedance due to motion, and is termed the 'motional electrical impedance'. The mechanical to electrical transformation ratio for impedances is therefore (Bl)^2 and is determined solely by the voice coil/magnet assembly.
Now in analysing such a system, one may choose to convert the mechanical components (mass, compliance, acoustic resistive or reactive loading etc) into electrical components or vice versa by referring the elements to one side or the other of the 'transformer'. It is usually easier to do the former and analyse the performance in the electrical domain. The mechanical/electrical transformer is of course an electric motor/generator. 
The transformation constant (Bl)^2 is a scalar and therefore does not change the phase angle of the impedance when transformed, only its magnitude. Therefore inductive components (masses) transform to inductances, and capacitive (compliances) transform to capacitors, whilst resistors (mechanical dampers) transform to resistors. 
The total electrical impedance seen at the voice coil by the amplifier, Zen, is given by the sum of the damped electrical impedance and the motional electrical impedance ie:
Zen =Ze1 +Zem
Now Zen can be represented as a series combination of R,L and C. The L represents the transformed mass of the cone in the mechanical cct, and the C represents the total transformed compliance of the driver. The R represents the sum of the transformed motional resistance plus the electrical (DC) resistance of the voice coil.
: This analysis appears to be original work.  Wikipedia is not the place to publish original work.  Tvaughan1 00:47, 15 October 2006 (UTC)
thread_title:  Transformation analysis 

message: It should be evident that damping of this (essentially second order) system can be accomplished either by mechanical means or by electrical means or by a combination of the two. There is however an inherent limitation in the 'electrical only' damping method. That is the finite resistance and inductance of the voice coil. This can only be reduced by the use of a 'negative' resistance in the amplifier and this is usually not employed for stability reasons (ie it tends to turn the system into an oscillator)
The complete electrical equivalent circuit of a loudspeaker in a cabinet is shown in the figure. 
For the system to be critically damped, we can see that in the electrical equivalent circuit, R must be of a certain (critical value.
To be continued... Please do not interrupt this post >:-{
--Light current 17:02, 26 April 2006 (UTC)
replies: text: Yes.  We do.  Across the full frequency range of the speaker.  But the article is about damping factor, so it needs to focus on how you design or evaluate an amplifier (which may have any speaker connected... cheap or well designed... in various configurations (alone, series, parallel), through wires with unknown length or resistance. Tvaughan1 22:38, 26 April 2006 (UTC)
thread_title:  Damping methods 

message: I can't believe this page! Its like 5 times as long as the article. Does anyone think this talk page needs some cleaning/archiving or something? Fresheneesz 04:17, 19 May 2006 (UTC)
replies: text: Ive archived about 40k s worth but we're still in the middle of a heated discussion so I think the rest should stay for a while. Just having a cool off between rounds!--Light current 13:22, 19 May 2006 (UTC)
thread_title:  Holy bejesus, cleanup? 

message: Is this page only applicable to audio amplifiers? Comming to a page on the damping factor, I would expect a more general treatment. For example, I was looking for the definition of the damping factor in terms of any general circuit. Does the definition of source impedance vs load impedance work in general, or just for audio amplifiers? Fresheneesz 00:22, 5 June 2006 (UTC)
replies: text: No, its not restricted to audio amps ATM! It should be a very general treatment.We could put a note at the top of the page saying this page only applies to audio and redirecting others to damping? The definition  'source impedance vs load impedance' is specifically reserved for audio amps and is not the general  defn of damping factor. Please see damping 8-)--Light current 00:30, 5 June 2006 (UTC)
thread_title:  audio only? 

message: I propose this page is called Loudspeaker damping factor to differentiate it from the other sort related to the detailed issue of damping.--Light current 15:46, 27 June 2006 (UTC)
replies: text: Damping has a section about loudspeakers, too.  Definitely need to either merge or disambiguate, depending on whether they're related enough — Omegatron 15:51, 27 June 2006 (UTC)
thread_title:  Page name 

message: I believe that critical damping of a loudseaker cone by electrical methods is, in almost all cases, impossible due to the non zero resistance of the voice coil.--Light current 10:30, 28 June 2006 (UTC)
replies: text: it is possible.  the poles are in the left half plane and can be canceled.  many speakers have a Qts < 0.5, and will be overdamped unless put in a box that is not "large" compared to Vas. —The preceding unsigned comment was added by 68.75.154.192 (talk) 01:39, 9 February 2007 (UTC)
thread_title:  Critical damping of loudspeakers