Can anyone comment on the subjective effects of “well-damped” speaker drivers… for example seas magnesium/Nextel?
What info I have gleaned indicates that ‘well-damped’ drivers tend to provide a smoother sound (potentially fuller sound?), as opposed to the more lively sound of, for example, Scanspeak revelator or Illuminator drivers that aren’t as ‘damped’, but use other methods (sliced cone, etc).
So just to be clear, I’m talking about the drivers only here, not the enclosure.
Would welcome discussion on what “Well-Damped” means to people.
Thanks
What info I have gleaned indicates that ‘well-damped’ drivers tend to provide a smoother sound (potentially fuller sound?), as opposed to the more lively sound of, for example, Scanspeak revelator or Illuminator drivers that aren’t as ‘damped’, but use other methods (sliced cone, etc).
So just to be clear, I’m talking about the drivers only here, not the enclosure.
Would welcome discussion on what “Well-Damped” means to people.
Thanks
There's not likely to be any real consistency here as there are far too many variables involved, both between driver design and implementation. However:
-Assuming you're talking about the cone, note that the Seas cast magnesium cones are the exact opposite of 'well-damped', at least as many would understand it, while the Nextel types are lurking somewhere in a mid-ground. In broad terms 'well-damped' in this sense usually means the cone has a significant amount of self-damping, either due to the material properties itself, a coating applied to all or parts of the substrate, or discontinuities in the substrate either through variable thickness, changes in material profile with glued slits, concentric rings etc. This usually (not invariably, but usually) means some kind of well-controlled TL modes being used to extend the upper BW limit. By contrast, something like the Seas cast magnesium cones have very little self-damping and are designed to have a single, or a small number of concentrated high Q breakup / bell modes toward the upper end of their response; there is little if any usable TL modes to extend the operating band, but good examples remain largely pistonic (i.e. use only front - rear oscillatory action) over their BW.*
-If it's T/S parameters we're talking about, it usually means a low Q drive unit; there isn't really a universal 'fixed' definition, but very roughly, something with a Qts < 0.3 could be described as progressively falling into that category.
*Metal cone full-range / wideband drive units e.g. Jordan's, many Markaudio, some TB units. are an exception, as although the cones are highly rigid, they are also designed to be highly resonant -it's how they produce a good portion of their BW; they attempt to varying degrees if success a reasonable degree of control over TL / resonant modes for their intended application via cone profile, suspension design, coil-coupling etc. (and sometimes additional damping).
-Assuming you're talking about the cone, note that the Seas cast magnesium cones are the exact opposite of 'well-damped', at least as many would understand it, while the Nextel types are lurking somewhere in a mid-ground. In broad terms 'well-damped' in this sense usually means the cone has a significant amount of self-damping, either due to the material properties itself, a coating applied to all or parts of the substrate, or discontinuities in the substrate either through variable thickness, changes in material profile with glued slits, concentric rings etc. This usually (not invariably, but usually) means some kind of well-controlled TL modes being used to extend the upper BW limit. By contrast, something like the Seas cast magnesium cones have very little self-damping and are designed to have a single, or a small number of concentrated high Q breakup / bell modes toward the upper end of their response; there is little if any usable TL modes to extend the operating band, but good examples remain largely pistonic (i.e. use only front - rear oscillatory action) over their BW.*
-If it's T/S parameters we're talking about, it usually means a low Q drive unit; there isn't really a universal 'fixed' definition, but very roughly, something with a Qts < 0.3 could be described as progressively falling into that category.
*Metal cone full-range / wideband drive units e.g. Jordan's, many Markaudio, some TB units. are an exception, as although the cones are highly rigid, they are also designed to be highly resonant -it's how they produce a good portion of their BW; they attempt to varying degrees if success a reasonable degree of control over TL / resonant modes for their intended application via cone profile, suspension design, coil-coupling etc. (and sometimes additional damping).
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Well, there is the usual two suspect resonances, the lower Fs and a "break-up" resonance. Resonances is what is in need to be damped. Need of damping is sign of resonances. What is damping and what is just structure can be hard to differentiate.
The lower one is described by the drivers Qts. For a "well damped" lower resonance you choose a driver with Qts 0,5. Lower value means even more damping and is not necessarily wanted. Higher means more and more undamped low frequency resonance.
The high frequency breakup has no standard value to be eyeballed so one have to read the frequency response scart. A straight line with the eventual drop indicated that there was no high frequency resonance i.e. either because there was no resonance and nothing to "damp" or some mechanisms that damped a resonance in a well made manner.
The you have everything between these two - undamped little resonances - they show up as peaks in the FR. The impedance trace also reveal some of them without a conclusive correspondence in the FR.
- But I think this is not the answer you where seeking really - you wonder about the cone material. But I tell you this - everything is in the FR and impedance trace. If these are ruler flat, there are no resonances. And it doesn't matter what the cone is made of. If resonances where dampen or not we will never know. But it doesn't matter - whats important is that they are not there.
Then of course manufactures tweak their presented measurement - thats one to look out for...
Good luck with your project!!
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The lower one is described by the drivers Qts. For a "well damped" lower resonance you choose a driver with Qts 0,5. Lower value means even more damping and is not necessarily wanted. Higher means more and more undamped low frequency resonance.
The high frequency breakup has no standard value to be eyeballed so one have to read the frequency response scart. A straight line with the eventual drop indicated that there was no high frequency resonance i.e. either because there was no resonance and nothing to "damp" or some mechanisms that damped a resonance in a well made manner.
The you have everything between these two - undamped little resonances - they show up as peaks in the FR. The impedance trace also reveal some of them without a conclusive correspondence in the FR.
- But I think this is not the answer you where seeking really - you wonder about the cone material. But I tell you this - everything is in the FR and impedance trace. If these are ruler flat, there are no resonances. And it doesn't matter what the cone is made of. If resonances where dampen or not we will never know. But it doesn't matter - whats important is that they are not there.
Then of course manufactures tweak their presented measurement - thats one to look out for...
Good luck with your project!!
//
Seas CA12, CA15, CA18
Monacor sph-145hq, sph-175hq, sph-220hq
Scan speak revelator (12M, 15W, 18W)
Monacor sph-145hq, sph-175hq, sph-220hq
Scan speak revelator (12M, 15W, 18W)
Very useful input - ok so look at the frequency response charts. Perhaps my question can’t yet be quantified - I guess a smooth sound is not fully related to driver cone material, or at least we might not be able to qualify it.
Perhaps it’s more about Qts then, with Qts 0.3 being very well damped. That said the uber (in every sense of the word) Ellipticor 18we has Qts 0.25, yet is reported to be a richer sounding driver than say an Illuminator. Could be it’s the super smooth FR, as a whole, and ignore the cone material type. Could even be the fact that it’s a bit richer in 2H. The variables are endless I guess.
Are you making a suggestion?
Perhaps it’s more about Qts then, with Qts 0.3 being very well damped. That said the uber (in every sense of the word) Ellipticor 18we has Qts 0.25, yet is reported to be a richer sounding driver than say an Illuminator. Could be it’s the super smooth FR, as a whole, and ignore the cone material type. Could even be the fact that it’s a bit richer in 2H. The variables are endless I guess.
Are you making a suggestion?
But remember, Its is only valid at the resonance frequency. All the rest is not described at all by Qts. One could have a Q 0,3 with a terribly resonant driver with a widely changing FR through the upper response. Qts and cone material has noting to do with eachother - here suspension stiffness and cone weight is the dominating factors.
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Amateur answer but I look for smooth waterfall plots.
If by well damped you mean minimal ringing
If by well damped you mean minimal ringing
Flat FR and flat impedance - with time... then direction is irrelevant because you cant do anything to it anyways. Polar plots follow EQ. One cant EQ only the 10 deg curve. Watch out for normalisation to 0 deg - this will tell you what you will achieve off axis when EQ straight on axis.
Impedance trace is a microscope of everything.... I'd like to see impedance waterfalls actually.
A drivers directivity is mostly given by its physical size. If it deviates from this physical fact, its most often due to bending wave modes which implies totally different directivity properties. Diffraction could be one other contributor for non linear FR for a driver (no box) but once mounted somehow that will dominate completely.
Balancing the answer to the question level might be useful for the audience...
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Impedance trace is a microscope of everything.... I'd like to see impedance waterfalls actually.
A drivers directivity is mostly given by its physical size. If it deviates from this physical fact, its most often due to bending wave modes which implies totally different directivity properties. Diffraction could be one other contributor for non linear FR for a driver (no box) but once mounted somehow that will dominate completely.
Balancing the answer to the question level might be useful for the audience...
//
The cone material does affect the sound and how one goes about designing a speaker. Hard stiff cones (e.g. SEAS magnesium) have large lightly damped resonances at relatively high frequencies above the passband of the driver. The cone moves essentially rigidly within the passband. If the resonances are driven even slightly they tend sound harsh and unpleasant. Soft less stiff cones are significantly damped because they contain resonances within the passband of the driver. These resonances are driven but they are small and benign. At the high frequency end of their passband the centre of the cone and the outside of the cone are moving differently and this changes the sound radiation pattern. It is this change in radiation pattern rather than the resonant motion that tends to be main cause of the different sound at least in well designed drivers.
Hardware priced and marketed like the Ellipticor drivers are aimed at the "ultra-fi" sector of the audiophile market where normal engineering considerations are relatively unimportant. What is important is that they are attractive to wealthy nontechnical people and that tends to be reflected in the marketing material. This doesn't mean they are technically poor drivers but that you shouldn't assume they are technically the best because they are way above the price where anyone primarily guided by engineering principles would be interested.
To me 'well damped' mean free of breakups. I worked with few drivers which came pretty close to be called well damped.
Here is example of two mids, but woofers and tweeters apply as well.
Vifa 13wh-00-08 is one, peerless tpy05w08 is other.
Attachments
It isn't precisely related to cone material; they can be connected but there isn't a black / white situation as it heavily depends on implementation. That said, a 'smooth sound' typically refers to a linear axial frequency response through intended operating region (aka the passband and transition band), and preferably maintaining that linear behaviour off axis to, say, 30 degrees, & preferably a bit more depending on the driver size etc. 'Smooth' also implies reasonably low levels of harmonic distortion, or in certain cases, possibly (possibly) some elevated 2nd order.
As has been alluded to, Thiele / Small parameters peter out above the driver's mass corner frequency (take 2Fs/Qes) where it moves into (theoretically) the mass-controlled band up to the point-source limit governed by voice coil diameter. Theoretically. This starts to vary if its designed to use TL modes (resonant or bending) to extend the band, and if it employs any measures to progressively decouple parts of the cone as frequency rises. But yes, the variables are more or less infinite.
I think this might be the answer…
Some of it is semantics I guess - some people have said to me, for example, that Nextel is ‘over-damped’ and smooth, and undynamic in comparison to revelator for example.
You can kinda hear the difference tonally (don’t chastise me for this!) on two YouTube videos by Mark84:
- Seas Nextel
- Scanspeak Revelator 18w mid.
Yes completely different song, but with headphones you can discern the tonal differences (and the Fusion, with the Revelator mid does have the same sound signature as the Illuminator I had).
Waterfall or step response probably isn’t the answer, and the relative drivers are being used in there passbands. Probably what Scott says then.
Some of it is semantics I guess - some people have said to me, for example, that Nextel is ‘over-damped’ and smooth, and undynamic in comparison to revelator for example.
You can kinda hear the difference tonally (don’t chastise me for this!) on two YouTube videos by Mark84:
Yes completely different song, but with headphones you can discern the tonal differences (and the Fusion, with the Revelator mid does have the same sound signature as the Illuminator I had).
Waterfall or step response probably isn’t the answer, and the relative drivers are being used in there passbands. Probably what Scott says then.
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Elevated HF will tend to be perceived as clearer and more dynamic than "lab-measured-ruler-flat". Even more so, considering the listening angles/distance/loudness/age which all diminish HF considerably. My phone suggests age-compensation HF boost, even for young people.
added: listening report
https://www.diyaudio.com/community/...-project-questions.391819/page-4#post-7166899
added: listening report
https://www.diyaudio.com/community/...-project-questions.391819/page-4#post-7166899
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We are listening to two different youtubes of two different speakers, in different rooms, playing different music, recorded by different microphones. There are so many uncontrolled variables involved here that it is impossible to determine what is causing any of the differences in sound. It could be driver differences, but it could also be a hundred other things.