It’s all about the initial resistance, the amount of initial power that is needed to overcome the friction and start to accelerate. And no, this does not show up in frequency response measurements. We are talking miliwatt area here, the minimum signal changes in music and how a mass/spring system reacts to it. It has nothing to do with heat at home audio levels, especially with high efficiency drivers. Talk to any pro or semi pro roadbiker about tires, it’s the same thing. A better tire does not ride any faster but it does respons faster to minimum energy changes. Most people probably never dissipate more than a tenth of a watt most of the time. 1 watt continues is bloody loud with 95dB+ drivers. Thermal compression plays a role in very low efficiency loudspeaker and in PA systems
many thx for your input
I also use a 15" up to 300hz with a 1st order xo. I find the woofer silent enough after the xo as well as fast enough, OFF AXIS
I guess i could use the faital or B&C 18" and keep listen off axis. that would make the peak inaudible. I already listen with no toe in at all...
accelration factor is: mass/BL
the faital 18FH500 indeed seem super fast. its acceleration factor is: 7.2 (137g/19 BL)
a little faster then the 18pzpb100 acceleration factor is: 6.5 (170g/26)
im using right now the eminence omega pro 15a woofer which acceleration factor is around 5 and seem fast enough for the audax mid
The formula is the other way around
Acceleration is BL/Mms. Otherwise the acceleration would be lower with higher driving force and we would all invest in the smallest possible magnet with the shortest possible voice coils.
The 18FH500 has therefore an acceleration of 19/0,137=138
The acceleration factor is an important indicator of how high on up the driver is usable and how it will match up with the midrange (or how a midrange will match up to a tweeter) The frequency response alone does not tell the whole story
Acceleration is BL/Mms. Otherwise the acceleration would be lower with higher driving force and we would all invest in the smallest possible magnet with the shortest possible voice coils.
The 18FH500 has therefore an acceleration of 19/0,137=138
The acceleration factor is an important indicator of how high on up the driver is usable and how it will match up with the midrange (or how a midrange will match up to a tweeter) The frequency response alone does not tell the whole story
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Let record tone bursts at this low lewels and compare shape(s). I'm lazy or I don't have time or something else🙄
and compression driver is faster😀, it's acceleration factor is, let's say, ~0.2. Will head and ears hurt when listening to such a system? Will the musicality of the music be destroyed when listening to such a system?
Oleg @olegtern , I'm worried, how are you? And how musically Perfect Circle yellow slug sing and thump with so different force factors?
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Yes, right, mass in denominator and in kilograms. "Acceleration factor", not acceleration. Multiplying by the current will give the acceleration. Simply more current will give more acceleration.
Like few thousands force factor for driver. 10000 for dome tweeter, hundreds for 6" woofers.
You obviously don't have any understanding of the topic so please stop talking nonsense and keep it to the serious questions
It's all about system matching and what parameters play a role in this process other than buying hundreds of drivers and starting to combine them randomly before anything satisfying rolls out.
I don't have to measure anything because it is already measured by the manufacturer and right there translated into parameters in the datasheet. That's the whole point of parameters. Why else do you think they come up with and provide all these parameters to begin with? They do mean something, it’s up to you how to interpret them but you only seem to make a joke out of it.
It's all about system matching and what parameters play a role in this process other than buying hundreds of drivers and starting to combine them randomly before anything satisfying rolls out.
I don't have to measure anything because it is already measured by the manufacturer and right there translated into parameters in the datasheet. That's the whole point of parameters. Why else do you think they come up with and provide all these parameters to begin with? They do mean something, it’s up to you how to interpret them but you only seem to make a joke out of it.
This is not nonsense, but sarcasm. Perhaps a little more sarcasm than necessary; but I came here already tired from a local forum where the same thing was discussed, like 20 years ago ..
Rms in a theoretically ideal form is harmless, but in real materials there is no ideal linearity under viscoelastic deformation. If Rms is relatively small, a small effect of Rms nonlinearity can also be expected at low volume. I use subs with Rms 2.5 kg/s and midbasses 3.5 kg/s or 2* 1.1 kg/s
As you rightly said, measuring the frequency response does not prove or disprove just about anything. It would be more interesting to compare the shape of the tone bursts.
I can't imagine nonlinearity of B at about zero displacement and current, accordingly, I cannot seriously discuss the force factor in this context.
Rms in a theoretically ideal form is harmless, but in real materials there is no ideal linearity under viscoelastic deformation. If Rms is relatively small, a small effect of Rms nonlinearity can also be expected at low volume. I use subs with Rms 2.5 kg/s and midbasses 3.5 kg/s or 2* 1.1 kg/s
As you rightly said, measuring the frequency response does not prove or disprove just about anything. It would be more interesting to compare the shape of the tone bursts.
I can't imagine nonlinearity of B at about zero displacement and current, accordingly, I cannot seriously discuss the force factor in this context.
dont ask me! no clue
logically the best would be to match drivers together with similar speed?
The best way I can quantify low level linearity of a driver is by looking at FR sweeps way under the typical 2.83v/m standard of measurement. There are distinct differences in FR and TSP when a driver is being tested at 0.283v, 0.4v, 0.566v, etc IOW starting at a tenth of the typocal drive levels. One watt on a high efficiency pro driver is about how loud on average most people listen, so the stuff thats sitting 20dB below the peak levels of the recording are certainly going to be affected if the driver doesnt respond in a linear fashion. This whole issue is also why the TSP test voltage can and will yield significant differences in the measured TSPs of said driver. These non-linearities show up almost everywhere in data, which is why manufacturers will note on their spec sheets what drive levels have been used for their data. Even if you could bother to measure them at these lower drive levels, the SNR limitations and noise floor of the measurement system would have a negative affect on accuracy in their results. Its interesting to note that every one of my favorite drivers have lower Rms, Mms, high BL and Qms. I didn't used to pay attention to these specs, but when I did, most of my go to drivers fell into this category of specs.
Eminence Definimax 4018LF
high inductance and heavy cone.
smooth roll off.
high excursion, so trades off sensitivity.
high inductance and heavy cone.
smooth roll off.
high excursion, so trades off sensitivity.
Low sensitivity drivers can still have other specs that lend rhemselves to good low level performance. You just have to drive them harder for the same spl. The definimax 4018LF is a great driver. The Rms of 3.4 isn't that bad for a large sub and the.rest of its specs are spot on to make it a good sounding driver. It just needs a big cab.
i guess i should get the faital 18fh500 as its the most efficient of the lot, which i will prefer to have with my audax mid.
is that the best recommendation in this thread?
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18fh510 is 0.5%=0.7 dB more efficient))
Definitely it's good recommendation. But don't forget 400+ litres Vas. For comparison: 4018LF - 250 l and 18hw1070 - 150-170 l.
According https://audioxpress.com/article/test-bench-the-18hw1070-18-pro-sound-woofer-from-faitalpro 18fh500 was tested in Voice Coil, November 2011
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I'd use the 18pzb100. It has lower mid band distortion, higher EBP and higher BL to Mms, plus Qts is considerably lower. Its a snappy sounding driver for an 18 and calculated efficiency is also higher. The big bonus is the price. In the end its your choice.
Honest 98db efficiency in half space=4% eta zero.
Datashits curves usually smoothed, you may want real measurements.
Run simple calculator, winisd or so, and see what you may get with 150 l box.