Yes but it also has electrical implications, because a dynamic loudspeaker is an electro-mechanical device. The lower the Q of the mechanical resonance, the voice coil becomes less reactive and more resistive (as we can see on the impedance curve), which means more heat is absorbed by the voice coil.
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well, Qms is only related to resonance, by definition at resonance the mechanical resistance is lowest (that's why you have the resonance, otherwise will be a flat curve). so what you saying its good that we have resonance because the resistance is lower there and there is less heat? neglecting the fact that the membrane operates also at other frequencies where there is no resonance and the resistance is much higher than at the resonance.
Quite so - I believe there's a lot to be said for elliptical cones. EMI used to make a (cheap) 13"x9" driver, and it was put to good use by Peter Baxandall in the late '60s:
https://keith-snook.info/wireless-w...ld-1968/Low-cost High-quality Loudspeaker.pdf
Maybe they went out of fashion because of how they look, plus the fact that they were associated with cheap drivers for the TVs of the day...
Yes, because if we can control the resonance via electricity (low Qes), then the resonance could become advantageous.
Also a low Qes means stronger motor in general, which means higher efficiency in the region where there is no resonance. So still less heat to the voice coil, than with a higher Qes driver.
I suppose you are talking about Rms? it is same as for the other woofers mentioned above, because the Md is about 1.5 times less then the mentioned peers and Rms is proportional to Md and invert to Qms, i.e. 1.5 times lower Qms and 1.5 times lower Md would result in same Rms.
Great, so there is consensus, lower Qts is good thing (a perfect woofer would have zero Qts) and this woofer is superior to peers. it has lower moving membrane mass , thus allows to have same Rms and resulting in lower Qm. The low mass and strong BL also result in low Qe and the combined together result in low Qts.
Not completely, because high Rms can result not only from high moving mass and low moving mass doesn't necessarily mean low Qms. It also matters how we achieve low Qts, because if extremely low Qms led us there (and not the low Qes), then it would mean such a degree of mechanical resistance that our speaker would not be able to move adequately. Welcome to the region of panel speakers, like electrostatics, planars etc., they are good, except for bass, where they should move more and more towards lower frequencies but can't because their mechanical resistance is so high, look at their impedance, they show almost zero Qms-like curves.
Too low Qes is almost the same, but if combined with high enough Qms, we just need more power and our dynamic woofer will move and not fry like an electrostatic or planar.
Too low Qes is almost the same, but if combined with high enough Qms, we just need more power and our dynamic woofer will move and not fry like an electrostatic or planar.
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The mechanical part, i.e. Qm has nothing to do with the electrical part. Qm=2xPi*f*(Mds+Mair)/Rms, wehre do you see electrical part in this equation? One can remove the coil and the amplifier and still will have the same Qm (well as long as the moving mass is the same, which means to add some mass to compensate for the missing coil. Also, I wander how the higher impedance at the resonance would increase the heat, i think it is just the opposite, when the impedance is higher the load is lesser. can you show a formula that proves the opposite.
"The mechanical part, i.e. Qm has nothing to do with the electrical part."
This is not true, because a lower Qms driver have lower electrical impedance peak at and around resonance than a higher Qms driver. The lower the Qms, the lower will be the impedance peak, which means the speaker as a whole is more resistive, which means they need to absorb more heat from the electrical driving, that's happens with planar speakers or with dynamic drivers much below their resonance (where their efficiency is low and the electrical impedance shows more resistive behaviour and they need more excursion for the same SPL) for example.
In an electro-mechanical device, you can't change the mechanical properties without affecting the electrical properties.
Just imagine a zero Qms driver. Of course zero mass or infinite high mechanical resistance doesn't exist but the closest real world example from speakers is a panel speaker, where the electrical impedance is almost fully resistive in the whole band. This resistive impedance is not there "just because", it is resistive, because the mechanical properties of this speaker is very resistive, in other words they don't really want to move much due to their high mechanical resistance, that's why they need to be big if we want lower frequency extensions from them at reasonable level and they heat up and/or fry relatively easy.
Sorry, I don't have formulas, this is just simple logic and observation on how speakers works in real world.
This is not true, because a lower Qms driver have lower electrical impedance peak at and around resonance than a higher Qms driver. The lower the Qms, the lower will be the impedance peak, which means the speaker as a whole is more resistive, which means they need to absorb more heat from the electrical driving, that's happens with planar speakers or with dynamic drivers much below their resonance (where their efficiency is low and the electrical impedance shows more resistive behaviour and they need more excursion for the same SPL) for example.
In an electro-mechanical device, you can't change the mechanical properties without affecting the electrical properties.
Just imagine a zero Qms driver. Of course zero mass or infinite high mechanical resistance doesn't exist but the closest real world example from speakers is a panel speaker, where the electrical impedance is almost fully resistive in the whole band. This resistive impedance is not there "just because", it is resistive, because the mechanical properties of this speaker is very resistive, in other words they don't really want to move much due to their high mechanical resistance, that's why they need to be big if we want lower frequency extensions from them at reasonable level and they heat up and/or fry relatively easy.
Sorry, I don't have formulas, this is just simple logic and observation on how speakers works in real world.
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Or just read what Audio Technology says about alu voice coil formers.
Drivers with alu VC formers shows lower Qms and higher Rms than drivers with non-conductive formers. This is because the electrically conductive formers acts as a brake against the moving of the driver and not because they are mechanically resistive but because they are electrically conductive and eddy currents in them acts as a brake which manifests as a mechanical property (lower Qms) of the driver.
https://audiotechnology.dk/faq/
Drivers with alu VC formers shows lower Qms and higher Rms than drivers with non-conductive formers. This is because the electrically conductive formers acts as a brake against the moving of the driver and not because they are mechanically resistive but because they are electrically conductive and eddy currents in them acts as a brake which manifests as a mechanical property (lower Qms) of the driver.
https://audiotechnology.dk/faq/
'Can be a good thing' for the first part, but it depends on context & implementation. 'No' for the second part, since Q is simply a mathematical construct derived from electrical filter theory, and you can't take it independently of all other factors in this context. A woofer with an Fs of, say, 40Hz and an infinite quantity of electromechanical damping (i.e. Qts = 0) would have no usable LF output. The equations have singularity with a 0 value, but if we make up the following fake parameters:
Fs = 40Hz
Qes = 0.001
Qms = 5
Qts = 0.001 [nearly]
Vas = 30 litres
Then:
-3dB mass corner frequency Fhm (take as 2Fs/Qts) = 80KHz.
Halve Fs: Fhm = 40KHz
Halve Fs again: Fhm = 20KHz
Halve it again: Fhm = 10KHz
Even if the Fs was 1Hz, with to all intents and purposes an infinite amount of electromechanical damping, you'd still have an Fhm of 2KHz, which isn't much use for a woofer.
To add to what @Scottmoose said - I would not agree that lower Qts is a good thing. The most useful woofers tend to have Qts from 0.28 to 0.42 ... and the most usable woofers are between 0.32 and 0.4 . So there is an optimum range of Qts, and it is very application dependent.
A woofer with a Qts that is lower than 0.28 is harder to use in a real world cabinet.
you are so wrong , Q applies to any resonance , electrical or mechanical, perhaps the mechanical has been studied much before the discovery of the electricity ...
Do you actually know where Q came from in loudspeaker enclosure & driver design? It was first used for practical purposes in Albert Thuras's work, which he derived from electrical filter theory, and was subesquently refined, using the same, by Novak, then Thiele, then Small. I suspect most people here are aware of its long-standing origins in mathematics. However, since we are dealing with driver characteristics as described in its fundamental properties, small & large-signal parameters etc. (usually now lumped for brevity under the T/S parameter handle), we stick to its functional origins within the subject. The fact that you have casually ignored the entire point of my post above, instead chosing to dispute the mathematical origins of Q as a descriptive concept (irrelevant to the subject) is -interesting.
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indeed , i have ignored the rest of what you said because it is irrelevant. I said a perfect sound tranduser will have a Qts of zero because there is no resonance and what you came with was an example where BL is infinite and there is resonance Fs. as Q is only relevant to resonance and a perfect sound transducer will not have resonance. and if it has no resonance then Q is zero, no?
and by the way i didn't want to offend anyone , i have the feeling i did somehow, sorry about that. my point was very simple and everything started from single observation that SS managed to reduce the cone breakup by changing the form to elliptical , that allowed them to make the moving mass lower and that led to lower Qms, keeping almost the same Rms as in the smaller size 32W and increasing the cone acceleration by 26pct. so well done!!!
"keeping almost the same Rms as in the smaller size 32W and increasing the cone acceleration by 26pct. so well done"
And the result is: F3 with a Qtc = 0.71 closed box loading is 76 Hz, with the factory recommended BR box is 54 Hz, whereas with a 32W, closed box F3 is 54 Hz and BR box F3 is 37 Hz, the other 32W goes even lower. Of course the 15" Ellipticor have higher sensitivity upper in the spectrum than the 32Ws.
And the result is: F3 with a Qtc = 0.71 closed box loading is 76 Hz, with the factory recommended BR box is 54 Hz, whereas with a 32W, closed box F3 is 54 Hz and BR box F3 is 37 Hz, the other 32W goes even lower. Of course the 15" Ellipticor have higher sensitivity upper in the spectrum than the 32Ws.
These new SS drivers with elliptical VC are needlesslly completely over engineered. The VC geometry is a weakness in design and will likely be a QC nightmare for them, along with consumers. The tolerances required to make this design work are needlessly tight and complex. I just don't see a point with this and can't imagine how high the failure rate will be. Considering the price of these new gems, they are out of reach for most diy people. Its just a total needless over-complication in design and looks to be a conversation piece at most. The design complexity is completely unnecessary for similar performance with a round VC former of equal materials. The price is ridiculous too. Who will spend this kind of money on drivers? I just don't get it.
Agree, you can get two BMS 18N862 on the price of one 15" Ellipticor for example, and the BMS will eat the SS for breakfast. At least in the bass range for sure.
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ScanSpeak makes beautiful stuff, but these ellipticores are just pointlessly over-engineered, not in a good way.
Despite my Bliesma incident, I still believe their drivers are far better than SS in terms of midranges and tweeters, for a fraction of the price. Bliesma makes the best Be drivers currently sold and they're competitively priced. Nobody else makes a 3" Be dome for a reasonable price. T34Bs are half the price of the equivalent SS Be dome.
I mostly buy the SS discovery line. Those drivers are worth the money and very well engineered. The 18W8542 is one of my favorite paper cone bass-mids. Likely the best paper cone driver in its class aside from the unobtainable Peerless NE123W, NE149W, NE180W and NE315W. The Ti VC formers they use are not in any other similarly prices driver.
BMS is a great company. They make beautiful stuff. Thats why JBL had to use them for diaphragm asys on the original 2407 driver, which is likely one of the best sounding 1" drivers in terms of HF quality. It exceeds the performance of many hifi domes on the right WG.
BMS LF drivers are second to none. Far better than anything in the same price range. Nothing else has the low THD capability while having that amount of dynamic range.
Despite my Bliesma incident, I still believe their drivers are far better than SS in terms of midranges and tweeters, for a fraction of the price. Bliesma makes the best Be drivers currently sold and they're competitively priced. Nobody else makes a 3" Be dome for a reasonable price. T34Bs are half the price of the equivalent SS Be dome.
I mostly buy the SS discovery line. Those drivers are worth the money and very well engineered. The 18W8542 is one of my favorite paper cone bass-mids. Likely the best paper cone driver in its class aside from the unobtainable Peerless NE123W, NE149W, NE180W and NE315W. The Ti VC formers they use are not in any other similarly prices driver.
BMS is a great company. They make beautiful stuff. Thats why JBL had to use them for diaphragm asys on the original 2407 driver, which is likely one of the best sounding 1" drivers in terms of HF quality. It exceeds the performance of many hifi domes on the right WG.
BMS LF drivers are second to none. Far better than anything in the same price range. Nothing else has the low THD capability while having that amount of dynamic range.