Some speaker driver measurements...

People always seem to get this wrong. Just like the amplifier brings the cone into motion it also brings it to a stop. The amplifier and motor are continuously moving the cone back and forth through the zero crossing. It can easily bring it to a stop at the zero crossing if that's what the music dictates.

And yes, when a transient occurs within the music the decay of said transient, either down to nothing, or to quieter parts is actually part of the music.

In theory it should be that way. If this was entirely true, we wouldn't have to look at the waterfall other than ridges of resonance and all drivers would shut down at the same time. In practise, inertia as a product of high mass in motion, is quite observable. I gave good example of Revelator 18w and 18m shown here on the forum compared waterfall side by side. Part of good waterfall is the ability of spring system to do it's job.
 
Last edited:
..Part of good waterfall is the ability of spring system to do it's job.

Compliance-wise a lot of this is down to the damping of the surround (..which is usually a small part of the compliance of the driver)..

The PPT is not only interesting in non-linear, it's also interesting in linear decay (waterfall) in-part due to the surround which seems to do 3 special things (..none of which are particularly special on their own, but are when combined):

1. High (relatively) linear excursion (though this is usually a spider issue, the surround can be a limiting factor when trying to achieve the next two things).
2. Removes (or at least "distributes" or "averages") the anti-phase resonance to where it's basically not there.
3. Sufficiently "dampen's" the outer-edge of the diaphragm relative to the driver's structure.

Diaphragm material and most notably the physical structure is predominate.

In fact its the structure that is the most important: diaphragm shape (geometry/profile), "dust" cone, pole-piece structure/diameter/material, etc..

Targeted cutting into (and re-adhering with a lossy glue) the diaphragm (and dust caps) of drivers with materials where you can do that: can vastly improve the linear decay of the driver.
 
Last edited:
There are other methods to achieve high internal loss/damping factor of the cabinet by utilizing a shear layer or viscoelastic layer, aka Constraint Layer Damping (CLD) in combination with dissimilar material. It could be a very attractive solution compared to relying on one material to have all the properties one are looking for. While Tank wood (like Panzerholtz) have attractive attributes and work well, it is an expensive solution.
 
I think the price must be so shocking that people are finding it challenging interpretting the data

Third comparison

Here's it again, @11.2V input
vs Satori MW16P-4 @2.83V input

In lay terms-
During rolling crescendos (eg. 32W input), this driver is cleaner than the Satori at 2W input!
Taking into account the difference in SPL sensitivity, at 10dB louder- it's still cleaner.

Incredible midrange
Incredible bass
Incredible dynamics

Two can play that game of course. This is my point of view:

Satori WO24P-4 vs Purifi PTT up to 300Hz distortion at 94dB (since that is maximum measured for PTT):

WO24P4 vs PTT.png

As seen from the pic, somewhat higher 2nd order in WO24P but everything else is better.

SB17NBAC35-8 vs Purifi PTT 300Hz-4kHz at 100dB loudness

SB17NBAC8 vs PTT.png

WO24P-4 and SB17NBAC35-8 combined cost is 265 euros. Throw in Peerless DA25TX and you are at 340 euros, still bellow 450 euros which is a price for one PTT midwoofer. That doesn't mean that you get lesser of a result of course. Three way mentioned would do more SPL with same (or better) distortion and for less money. At the expense od 50 liters enclosure, true.
 
Last edited:
And that is why SB Acoustics is difficult to beat!

Damn you're logic and Zvu are snapping me back to reality if you want insane high quality output buy JBL M2 OR 4367 building a system with 8 to 10 PTT is not too far off 4367 . SB TEXTRENE and other drivers are going to offer a compelling high end build and those 13.5 inch are coming, that will be trouser flapping bass
 
I do not disagree, however.... when it comes to the observed acoustic event, we are not dealing with magic.

Determining factors:
On- and off axis response.
Impedance response.
Harmonic content.
Inter Modulation Distortion.
Transient response, Impulse Response (Step respons) & Energy Time Curve

The party trick is to mate the driver to the "right" cabinet and properly deal with internal reflection as well as diffraction. Basically, the cleaner everything is in terms of low distortion the better. I am aware of the subjective aspects which apply to every engineer/listener (no exceptions). As I mentioned earlier: An acoustic instrument produce music while a loudspeaker REPRODUCE music - The complex part (if you like) is the subjective aspects of what sounds good or not and the issue with that is, its subjective. Its virtually impossible to agree, but sometimes, you will find camps were they mostly agree but never fully. So in a way, subjectively talking about which driver(s) or loudspeaker(s) that is excellent or stellar is meaningless. The hope and real endeavors are achieved in the objective aspects because it is non subjective.
 

Attachments

  • 75557516_1326162300920037_8638390675026477056_o.jpg
    75557516_1326162300920037_8638390675026477056_o.jpg
    222.7 KB · Views: 383
Determining factors:
On- and off axis response.
Impedance response.
Harmonic content.
Inter Modulation Distortion.
Transient response, Impulse Response (Step respons) & Energy Time Curve

Impedance is one of those things that mostly affects how you get to the desired acoustical result, since we are usually more concerned with the pressure level some distance from the speaker.
Harmonic and modulation products stem from the fundamental nonlinearity of the test system. Putting in one or several tones is just an easily quantified means of probing its characteristics.
Step response, spectral decay, ETC, and so on amount to alternative representations of the information provided by the impulse/frequency response. I do have to ask what behavior is made apparent that you couldn't clearly see under the existing representations.

Did SBA ever mention they were going to sell the 13.5 inch driver? I saw that they had prototypes that were shelved from a lack of perceived market interest.
 
Last edited:
I do not disagree, however.... when it comes to the observed acoustic event, we are not dealing with magic.

Determining factors:
On- and off axis response.
Impedance response.
Harmonic content.
Inter Modulation Distortion.
Transient response, Impulse Response (Step respons) & Energy Time Curve

The party trick is to mate the driver to the "right" cabinet and properly deal with internal reflection as well as diffraction. Basically, the cleaner everything is in terms of low distortion the better. I am aware of the subjective aspects which apply to every engineer/listener (no exceptions). As I mentioned earlier: An acoustic instrument produce music while a loudspeaker REPRODUCE music - The complex part (if you like) is the subjective aspects of what sounds good or not and the issue with that is, its subjective. Its virtually impossible to agree, but sometimes, you will find camps were they mostly agree but never fully. So in a way, subjectively talking about which driver(s) or loudspeaker(s) that is excellent or stellar is meaningless. The hope and real endeavors are achieved in the objective aspects because it is non subjective.

And it can be done even without dsp and multichannel - with a little knowledge and effort involved. I really enjoyed John Darko's comparison between Kii3 vs Kef Reference 1 + Hegel H590 amp - active DSP vs passive system. Kinda new before watching who will win but it was fun watching nevertheless.
 
Last edited:
I do have to ask what behavior is made apparent that you couldn't clearly see under the existing representations.

Did SBA ever mention they were going to sell the 13.5 inch driver? I saw that they had prototypes that were shelved from a lack of perceived market interest.
In terms of behavior, the more pistonic or linear motion the driver has with lower internal resonance, the cleaner it will reproduce the signal, so in terms of what splendid drivers need to have or do, its fairly obvious. Achieving it IRL is.. well, challenging to say the least. Pistonic and linear behavior is and has to be monitored or measured in several ways. Plotting the Bl curve is another nice way to add to the complexity. SBA might have found a very nice material and implementation through the TeXtreme. But we need impartial 3rd parties to test the driver(s) to avoid to much biased results.

What we know so far is that the 13.5" exist as a prototype and that me among others have expressed and interest. Until and if Ulrik (USXX) provide more info or updates, what will happen is uncertain. I for one hope it will be released under the TX line.
 
The cone material that they need to use is hardened steel. Its stiffness to weight ratio is significantly better than aluminum, and the breakup frequency would be extremely high. It's also extremely consistent material.

I hope that's a joke. Steel would be constantly attracted to the magnet, and eventually ruin the suspension.
Wolf
 
I hope that's a joke. Steel would be constantly attracted to the magnet, and eventually ruin the suspension.
Wolf
Can't beat science those so called aluminium billet cones from YG Acoustic are supposed to be terrific but somehow I cannot see the boss allowing Wolf to take apart his $5000 drivers only to discover there from a secret HiVi Swan factory in Guangdong 😁
 
Can't beat science those so called aluminium billet cones from YG Acoustic are supposed to be terrific but somehow I cannot see the boss allowing Wolf to take apart his $5000 drivers only to discover there from a secret HiVi Swan factory in Guangdong 😁
How is that possible ? The motor comes from ScanSpeak Illuminator series and the cone is produced in house or by a neighbor facility. There is nothing secret about the YG Acoustics BilletCore Cone. I have personally held the cone in my hands and inspected it.
 
In terms of behavior, the more pistonic or linear motion the driver has with lower internal resonance, the cleaner it will reproduce the signal, so in terms of what splendid drivers need to have or do, its fairly obvious. Achieving it IRL is.. well, challenging to say the least. Pistonic and linear behavior is and has to be monitored or measured in several ways. Plotting the Bl curve is another nice way to add to the complexity. SBA might have found a very nice material and implementation through the TeXtreme. But we need impartial 3rd parties to test the driver(s) to avoid to much biased results.
The membrane as a surface with a uniform velocity and the complete driver's nonlinear behavior are not so strictly related. Modes, higher orders and otherwise, are normally tackled in the linear limit, even though certain types of modes can set up interesting types of distortion. But what relation are you trying to draw between rigidity and the measurement?
 
But what relation are you trying to draw between rigidity and the measurement?
Straight forward, rigidity mean stiffness or compliance (how much an object yield or confirm to an external force). This is strictly applied to the cone in this instance. Low compliance mean that an external force have low influence on the structure and high compliance mean it has a high influence. Untreated paper has high compliance and diamond has low compliance. But material is only one aspect. Rigidity can also come from the shape or how material is distributed, but, to keep things simple. The stiffer the cone is the less it will deform and hence less nodes and anti-nodes.

https%3A%2F%2Fwww.audioxpress.com%2Fassets%2Fupload%2Fimages%2F1%2F20190425104919_Figure1-TeXtremeDiaphragm.jpg


As seen in the picture above (Titanium to the left and thin ply carbon diaphragm on the right (TeXtreme)), the node or cone breakup behavior is very different between the solid Titanium cone and carbon weave. The construction is also very different. The former cone rely on one material while the weave rely on at least 2, the weave + resin or glue (bonding agent). The weave create an interference pattern while the Titanium does not, the weave has resonance canceling properties similar to a sandwich cone which use at least two different material properties, like what Vandersteen does.

“Pistonic” refers to the motion of the driver cone in response to the audio signal from the driver’s voice coil. If the driver cone stays rigid and moves in and out in truly pistonic fashion, distortion is avoided and the purest replica possible of the signal from the amplifer is produced by the speaker. If any part of the cone flexes or bends in the opposite direction of the signal, part of the cone is out of phase, and distortion is output from the loudspeaker.
A loudspeaker driver has one job, to induce vibrations that propagates as an audible wave of pressure, through a transmission medium (air) and is translated to sound in our brain. So, we could be here all day talking about material, shape, size etc. but that would be very limiting. That is why, if we include the 3 Octave Rule, things might not be as cumbersome.

Most drivers have a specific area or frequency band they like to operate in and this is very much related to surface are (or Sd as we like to call it :)). The larger the area the less you can control outside its happy frequency range, typically its 3-4 octaves which is evident in the linear region. Once resonance, cone breakup, nodes and anti-nodes (areas out of phase irregularly distributed in the cone) the more noise it will produce, evident in the irregular and erratic behavior we see, evident in, typically, the higher frequency range of the driver, in the harmonic content and IMD.

To be fair, all drivers have an area of pistonic and linear region, the ideal is to have that for as long as possible. The other chapters of the perfect pistonic driver is down to how well the suspension and motor can control the cone motion. But I will say that in 2019, that is not so much of an issue.

I am not an engineer, so if some of the wording is off or I am missing to include a definition, please excuse me.

Link 1: The Truth About Pistonic Driver Cones | Vandersteen Audio
Link 2; UltraAudio.com Feature Article - Searching for the Extreme: Richard Vandersteen of Vandersteen Audio: Part One (9/2009)