I'm in the brainstorming phase of a new speaker build which lead me to create an excel sheet with those accelleration factors including matching factor.
I thought i can share it to you.
Source of the Accelleration Factor:
Motor acceleration 'Γ' in moving coil loudspeakers
And here is the sheet
the prices are taken from soundimport , so you might get it cheaper somewhere.
Edit: i did filter it by the Sd value. so dont wonder why the manufacturers are mixed up
I thought i can share it to you.
Source of the Accelleration Factor:
Motor acceleration 'Γ' in moving coil loudspeakers
And here is the sheet
the prices are taken from soundimport , so you might get it cheaper somewhere.
Edit: i did filter it by the Sd value. so dont wonder why the manufacturers are mixed up
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Why is this acceleration factor of any importance when we have to measure the acoustic output anyway in order to design a reasonably linear loudspeaker system?
I certainly am. Places like these get so boring when everyone agrees and tries to p&@!$$ a little bit further than the other.
But do know I do understand. My work environment is full of social workers and psychologists. So trust me, the QUACK factor has no secrets to me whatsoever.
Are they slightly different, as sensitivity can be partly achieved by resonances. A resonent ported box can by more sensitive in the bass than an aperiodic enclosure, but have less acceleration.
Similarly, a large cone can have the same sensitivity as lots of small cones, but the small cones will be moving with pistonic motion, but the large cone will be rippling like a pond.
Similarly, a large cone can have the same sensitivity as lots of small cones, but the small cones will be moving with pistonic motion, but the large cone will be rippling like a pond.
Inductance (Le) governs woofer 'speed' and its upper mass corner (Fhm) governs its acceleration BW, ergo seems like Qts' governs its acceleration factor (whatever that is) or would it be a combination of Le & Qts'?
Fhm = 2*Fs/Qts'
Qts': 2*Fs/Fhm
Fs: Fhm*Qts'/2
(Qts'): (Qts) + any added series resistance (Rs)
Fhm = 2*Fs/Qts'
Qts': 2*Fs/Fhm
Fs: Fhm*Qts'/2
(Qts'): (Qts) + any added series resistance (Rs)
I know this article.
let me share my personal thoughts. (i dont claim that im right or correct with this)
inductance reduces frequency response, yes. you can simulate that in winisd in the advanced section.
what is maybe not noticed/overseen in this article that putting an coil in the path of the signal you also add resistance.
and a coil and a resistor is used as: contour network and has exactly the effect that happened in this article.
is it wrong ? is it correct ? i will not judge it because its not why i linked my excel.
the idea of my file was beneficial. i m asking and others here are spending their time to give answers which helps me build better speakers.
therefore i put my work as a small thx for that. who wants to used it should take it, who not -well then let it be.
the inital start for it was , that i found the accelleration factor on a datasheet of a driver. sadly, i cant remember which company it was.
To me the acceleration factor seems as useful as the color of the magnet. One better regards the usual suspects. Any (Klippel) driver test on the sites that come by here delivers better judging parameters. We all want a Lamborghini. But the thing is useless in everyday life of 99% of us normal people.
Acceleration factor is just another way of describing overall conversion efficiency (η0). As GM pointed out, transient response in the mass-controlled region of the driver's response is a function of BW & the HF limit, with behaviour below that a function of the driver's electromechanical resonance / damping and the alignment used. Γ might make a quick & dirty assessment of the possible mechanical efficiency of a driver designed to use TL modes to extend its HF response -but since it can't account for the progressive decoupling of portions of the cone (or all of it) at higher frequencies, it's limited even there. I do an auto-calculation of it in my Excel 'sheet of many things' which I put together to cross-check various data, since it only took me about 10 seconds to enter the equation (and Ergle's conversion from ms^2 into G) but I usually don't bother with it. Still, since it's there, not entirely without interest as it may help you spot possible anomolies elsewhere for e.g. & it's 'another point of reference' even if in itself it doesn't tell you much.
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Sort of. The point of Dan's article & what GM was showing is that transient response in the mass-controlled region is ultimately a function of bandwidth, which is ultimately limited by coil inductance since the driver's voice coil itself is an inductor & ultimately acts as a 1st order LP filter. So coil inductance Le & the driver's nominal impedance Re gives you the resistive portion, albeit in practice it's frequency varient, the extent of which depending on the motor design.
Where it can get interesting is in situations where the nominal electrical corner doesn't match the acoustic / mechanical (not uncommon), either because the cone has gone into chaotic breakup before the coil inductance starts to roll things off, or controlled TL modes in the cone & / or a direct-coupled cap or sub-cone are used to extend the response above its nominal mechanical piston range, in which case you'll probably be in a 'how long is a piece of string' scenario as this is an operating condition that can't be accurately predicted from the fundamental parameters.
Audiotechnology / Skaaning ususally states it in they're datasheets.
Also BL and mms by itself is not enough either way.
A drivers Re, and inductance Le also comes into play.
The resistive area of the acoustic impedance on the cone might be of interest too… but all in all it’s not that smart to isolate such a simple parameter as motor force divided by cone mass. What is cone mass by the way? If one really persists, use such derived parameters in conjunction with other, more relevant ones.
By far, Le is more important than BL. The problem with a higher Le is it can mask some FR issues and it causes higher IMD with increasing cone excursion. You may think your driver has smooth FR, but the modulating Le causes all sorts of side band distortion which your stuck with. In the case of a low Le driver, you can always add series inductance to cross it lower. Also, BL changes with impedance on same model drivers of different impedances, so its dependent on the amount of VC windings on each specific impedance version. The more windings, the higher the BL and Le.
The formula at the site linked above doesn't really help that much 🙂.
Qts' is calculated as follows, given the driver T-S parameters and series resistance Rs:
Qes' = Qes * (1 + Rs / Re)
Qts' = Qes' * Qms / (Qes' + Qms)
ok, hat is a lot of information that leads me to the following question:
how can i see in the tsp if a driver will produce better transient responses than an other driver before i buy the driver.
maybe you can show me at an example: 12MU/8731T00 vs L19RNX1
how can i see in the tsp if a driver will produce better transient responses than an other driver before i buy the driver.
maybe you can show me at an example: 12MU/8731T00 vs L19RNX1
Perfect transient response is only possible with a system with unlimited bandwidth and perfect linearity. So there you go. You pick a midrange driver and a bass midrange. Both have unique transient responses and none of them is arguably better than the other. The midrange lacks in low frequency reproduction and the bass-mid can't keep up with the high frequency reproduction.
And you haven't even specified the required sound pressure level of the transient. As a side story: KEF started long ago testing real transient responses in order to perform Fourier analysis. IIRC they had trouble reaching enough level to make the measurements useable, as the drivers found themselves quickly overloaded and distorted big time.
But: the moment you throw these drivers into an equation with multiple drivers, enclosure and crossover, literally everything changes. At that moment both systems, in which both drivers have found their application, can have an equal transient response.
And you haven't even specified the required sound pressure level of the transient. As a side story: KEF started long ago testing real transient responses in order to perform Fourier analysis. IIRC they had trouble reaching enough level to make the measurements useable, as the drivers found themselves quickly overloaded and distorted big time.
But: the moment you throw these drivers into an equation with multiple drivers, enclosure and crossover, literally everything changes. At that moment both systems, in which both drivers have found their application, can have an equal transient response.