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Purifi PTT6.5W04-01A 6.5" midwoofer

VintageFlanker

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Sorry if I offended someone, but I use my (pretty good) ears to listen, not theories. We still don't know everything about sound reproduction.
My personal experience with JBL123A proves that. I built the sealed 120l cabinets for them and all who listen agree that it is the most realistic bass they ever heard.
"Uh-Uh"

Welcome, anyway!;)
 
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Neither of them are dragsters.
We don't have many traffic lights here nor many straight roads so "fast" has never had any relationship to standing start acceleration.
Sorry, I was too cryptic, Frank.

My point is that a dynamic driver accelerates in a straight line. IOW, is the higher mass a problem in this context? Especially up to 2-3kHz, not 20?
 
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IOW, is the higher mass a problem in this context?
The upper bandwidth of a cone is limited by motor inductance which forces lowpass behavior, as well as the geometry. A massive piston has no intrinsic upper limit on the central axis, although a rigid cone would be expected to slope off eventually.
Acoustic efficiency in the zone above Fs, the mass-controlled range, is decreased. The motor expends most of its force accelerating the cone mass and not on its coupling to the air load.
 
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What do you mean by both?
Purifi's woofer has a modest midband sensitivity for 4-ohm nominal driver with a fairly high BL product.
 
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Lowpass behavior and decreasing acoustic efficiency.

Not trying to be a smart-ass. Just want to learn something :)

teddy27 seems to claim that the shortcomings of this driver won't be evident in measurements.
Series inductance limits high-frequency response by a first-order LP. There's much more to the driver's stationary impedance than a simple RL, and the impedance trace of the driver will reflect that. Iron exhibits a strong skin effect even in the bass range, which reduces effective inductance at higher frequencies and leads to a shallower slope. This also suggests that the low-frequency inductance may be much higher than naively expected of a simple air coil. The shorting rings counteract the induced magnetic fields, which partially checks the bandwidth limiting and nonlinearity of inductance.
The loss of midrange efficiency reflects the increased mass by F=ma. Axial SPL is directly tied to the acceleration of the driver, so more mass equals less acceleration per unit force when the driver is mass bound. These are all visible in measurements, although characterizing the frequency-dependent inductance neatly is difficult.

I would share the dismissive attitudes taken to that post. I am not enamored with direct-radiating pistons and think that audio should try to get away from them, but the reasons teddy27 gave do not follow.

Edit: Additional reading.
 
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Track times tell a different story.

Where even the cheapie Caterham beats the regular EB version, and the Dodge Viper beats the Super Sport.

The Veyron EB ranks #30.

https://fastestlaps.com/tracks/top-gear-track
H
So, let's see- appeal to emotion, bad car analogy, dismissal of physics with the obligatory ignorance of Fourier, irrelevant anecdote, dismissal of physics again, then the usual "we don't know everything" fallacy. Very nice first post! You managed to pack it all in.
Hi there, SIY, you don't understand what I am talking about. It happens to be that I am an automotive engineer with long experience and few acoustic patents. Veyron has 1000 horses, not 140 like old Elise. Give Elise 500 horses and compare the response. The car comparison is very good. I am talking about handling, not acceleration numbers.
Anyway, to answer to your insult, yes emotions are very important in music. Music is about emotions. Sorry, I can't communicate with people who don't have emotions. I am still a human, not a machine which use only numbers, very often applied to the wrong places. I am not against mathematics. It is the language of Universal Creation. My advice: keep your EGO for yourself. Mocking doesn't answer anything and only creates unnecessary tension. Do you like it? I don't

Important is what we measure. So far, nobody, for example was able to measure loudspeaker's timing alignment. If you know it, please let me know. What theory do you apply? I am doing it according to my listening and it works. Cheers
 

Julf

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So far, nobody, for example was able to measure loudspeaker timing alignment.
What exactly do you mean by "timing alignment". There is a fair bit of software out there for measuring phase response.
 

Ilkless

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H


Hi there, SIY, you don't understand what I am talking about. It happens to be that I am an automotive engineer with long experience and few acoustic patents. Veyron has 1000 horses, not 140 like old Elise. Give Elise 500 horses and compare the response. The car comparison is very good. I am talking about handling, not acceleration numbers.
Anyway, to answer to your insult, yes emotions are very important in music. Music is about emotions. Sorry, I can't communicate with people who don't have emotions. I am still a human, not a machine which use only numbers, very often applied to the wrong places. I am not against mathematics. It is the language of Universal Creation. My advice: keep your EGO for yourself. Mocking doesn't answer anything and only creates unnecessary tension. Do you like it? I don't

Important is what we measure. So far, nobody, for example was able to measure loudspeaker's timing alignment. If you know it, please let me know. What theory do you apply? I am doing it according to my listening and it works. Cheers
https://adireaudio.com/wp-content/uploads/2018/12/Adire-Audio-Woofer-Speed-by-Dan-Wiggins.pdf

Here's a white paper by Dan Wiggins, an esteemed driver designer "with long experience" who has made foundational innovations in transducer design (with a "few acoustic patents"). He shows why your intuition that moving mass is related to speed does not match up with the mathematics, something alluded to by previous posters already. Moving mass affects sensitivity (experiment here verifies Wiggins' math with extensive direct measurements of "speed").
 

Julf

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VintageFlanker

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Anyway, to answer to your insult, yes emotions are very important in music. Music is about emotions.
Nobody here said otherwise.
Sorry, I can't communicate with people who don't have emotions.
You mean robots? There isn't any on ASR to my knowledge.:p
More seriously, about the Emotions vs Measurements:
The major problem is: audiophiles seem to do not understand this very simple point:
First : Emotion/communication/inspiration/soul or whatever are in the music itself, not in the gear.
Second: that is the music reproduction abilities which are measured, not the music itself. Then, you cannot distinguish music reproduction (fidelity) from measurements.
As a new member, I suggest you take a look at the Beta-ASR Manifesto.

Welcome aboard!;)
 
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There will be an active and passive version. The passive market is too big to ignore. I was trying to get a prototype ready for the Melbourne show but Purifi didnt have the drivers available in time.

I use the Mudorf AMT in my main speakers, active 3 way and its excellent there, but for a 2 way you have got to start making compromises on the crossover point (how low you can go.)

Probably not going to say too much else at this moment. ;)
Looking forward to new developments on the subject, I will buy a passive pair as soon as you have them ready.
 

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