All about Excursion.... - Page 2

Kryptonitewhite · 03-17-2008

So the solo really is only good up to 24.5mm? After that nothing? As the tutorial said, it's highly debated.

I had several S15L7's and 2 AA 15" Avalanches....both had an Xmech of 32mm, but the Avalanche had 27mm Xmax and the L7 only had 16.5mm.

1: the L7 moved just as far as the Avalanche, and sounded as good, but a little louder ( same excursion but more cone area)

2: 16.5mm Xmax is 1/2 it's 32 Xmech and you couldn't hear much change...more importantly..you couldn't suddenly hear it pass Xmax over 1/2 it's excursion. At full excursion, it sounded just as good as the Avalanche.

If I had the money, I'd love to have an 06' XXX 18 that's within Xmax at full excursion, 54mm... but for a fraction of the cost, and having experienced Kicker vs super Xmax subs...I would simply like to get the Xmech, bull**** and argument free, but I'd be more than glad to have a separate thread to debate the issue.

Funny when someone asks for any spec, at that given moment it's "why? what for? youre doing something wrong. you don't know what youre talking about" but then ask for a diff spec, same thing.

What I mea is I used to have this same argument about Xmax a year ago. When the HaVoc came out (Ascendant Audio) there was a huge fight that Xmax doesn't matter on that sub. Now it's Xmech doesnt matter on this sub. people get this idea that subs only work for 1 application. SPL sub. SQ sub. Bandpass or sealed cuz of EBP. Ported or 6th order.

A sub is a sub. they all have different characteristics that may make it easier to build a more efficient (as in box size or port lenght) box for desired output, but all subs can work in all boxes.

Specs are given for a reason. I want those specs. If I am interested in a motor, don't tell me I don't need to know displacement or torque or horse power. This is a place to go to get info. I want that info. Start a new thread on why, I'll be glad to go there and debate all day :P

Not tryin to be a dick, just never seem to get answers, only static and skepticism

almond · 03-17-2008

Quote:

Originally Posted by Kryptonitewhite

So the solo really is only good up to 24.5mm? After that nothing? As the tutorial said, it's highly debated.

I had several S15L7's and 2 AA 15" Avalanches....both had an Xmech of 32mm, but the Avalanche had 27mm Xmax and the L7 only had 16.5mm.

1: the L7 moved just as far as the Avalanche, and sounded as good, but a little louder ( same excursion but more cone area, and cuz distortion makes louder)
2: 16.5mm Xmax is 1/2 it's 32 Xmech and you couldn't hear much change...more importantly..you couldn't suddenly hear it pass Xmax over 1/2 it's excursion. At full excursion, it sounded just as good as the Avalanche.

If I had the money, I'd love to have an 06' XXX 18 that's within Xmax at full excursion, 54mm... but for a fraction of the cost, and having experienced Kicker vs super Xmax subs...I would simply like to get the Xmech, bull**** and argument free, but I'd be more than glad to have a separate thread to debate the issue.

Funny when someone asks for any spec, at that given moment it's "why? what for? youre doing something wrong. you don't know what youre talking about" but then ask for a diff spec, same thing.

What I mea is I used to have this same argument about Xmax a year ago. When the HaVoc came out (Ascendant Audio) there was a huge fight that Xmax doesn't matter on that sub. Now it's Xmech doesnt matter on this sub. people get this idea that subs only work for 1 application. SPL sub. SQ sub. Bandpass or sealed cuz of EBP. Ported or 6th order.

A sub is a sub. they all have different characteristics that may make it easier to build a more efficient (as in box size or port lenght) box for desired output, but all subs can work in all boxes.

Specs are given for a reason. I want those specs. If I am interested in a motor, don't tell me I don't need to know displacement or torque or horse power. This is a place to go to get info. I want that info. Start a new thread on why, I'll be glad to go there and debate all day :P

Not tryin to be a dick, just never seem to get answers, only static and skepticism

the ear is a very unreliable way of determining if sub A is louder or cleaner than sub B. with out any kind of mechanical meauserments it's hard to tell what was really happening.

Kryptonitewhite · 03-17-2008

Quote:

Originally Posted by almond

the ear is a very unreliable way of determining if sub A is louder or cleaner than sub B. with out any kind of mechanical meauserments it's hard to tell what was really happening.

Thank you. So for me personally, I can't "hear" the difference so I will be perfectly happy.

However, overall output, is simply air moved. If a XXX 18 at full excursion and a SOLOX 18 at full excursion both sound the same TO ME, and I am perfectly happy with either....but mathmatically if I take Sd X 2(Xmech) I get total p-p Vd. If the SOLO has 54mm as well, then the Sd makes it louder, and TO ME, sounds the same, just louder. Then I'll spend the $750 for the SOLO cuz it will make ME happy, though I'd still rather the $2500 XXX (making that up...but if you know about how much, I would like to know too!) if I were rich cuz in my mind I KNOW its better...or is it? LOL :P

Cap'n'Crunch · 03-17-2008

why did you dig this up just to be wrong?

Kryptonitewhite · 03-17-2008

what you mean?

trd-gt · 06-07-2009

can a sub get excursion at a high frequency? i have only seen it at low hz,sorry if its a newb question

Solid_State13 · 06-07-2009

by "get excursion" im guessing you mean that you can visibly see the sub moving in and out. excursion is how speakers make sound, so all speakers have excursion as long as they are making noise.

yes it is possible, but you need a lot of power and a sub that can take it. I'm assuming you have seen a sin wave before? if not just google image it. that is essentially what the subwoofer is doing as its playing (with music, its more complex, but for a simple tone, thats it). so as the wave goes up, the subwoofer is moving out then back in to the neutral and then in. so on lower notes, the wavelengths are longer, giving the sub more time to move in either direction. with higher notes, its the opposite: less time to move in either direction. so to make a sub reach full excursion at a high frequency, you need the sub to move the same distance in half the time (for, say 30Hz vs 60Hz).

Eagle · 06-07-2009

30hz's is 30 times per sec.,40hz's is 40 times per sec. and so on! That is why the sub moves more at lower hz's

GTR-34 · 12-13-2009

informative indeed
what role does a sensitivity play ? is it always important ?

welcome2hell1 · 04-12-2010

So more clearly...let's say my pioneer champion series ts-w307d4 is listed at 11 mm (half an inch xmax), does it mean the maximum movement is half an inch? or does it mean the movement in one way is half an inch, so the total movement is a complete inch??

nx04gt · 04-24-2010

sony xplod ftw from wal mart

Kryptonitewhite · 04-24-2010

Quote:

Originally Posted by DevilDriver

Excursion is a large contributor to high output in any driver on the market. Typically, larger excursion (seen visually as how far the cone moves in and out) means more sonic output. However, with excursion come challenges.

As the driver moves outward, the voice coil begins to move out of the gap. This causes a drop in the magnetic force (or BL) and results in a few negative effects, including a large theile/small parameter shift, lower efficiency (magnetic flux decreases), less control over the voice coil (transient response increases, making the driver sound sloppy), and introduces distortion into the output.

Knowing these effects, there was a need to design a parameter to describe the limit of excursion while still remaining “linear”. The idea here was to define a point at which all other parameters remain the same and also consider the limits at which disortion becomes audible. This parameter is referred to as Xmax and, although extremely valuable, is highly controversial. The issue comes back to the actual definition.

Overhang
Traditionally, Xmax has been defined by the overhang method. Overhang is the length of coil in mm that extends past either side of the top plate and is determined by the formula:
Xmax = gap height – [voice coil length/2]
The theory here is that this measurement considers the maximum amount of travel the driver is capable of with the same number of windings (of the voice coil’s wire) in the gap. Once the number of windings decreases, the effects listed above will begin to occur. This is still one of the most commonly used definitions and does work fairly well, but it does not consider several factors, including the behaviour of the magnetic fringe field, any suspension compliance non-linearities, any inductance non-linearities, or InterModulation Distortion. From this lack of refinement, several other definitions have come about.

8mm In the Gap
Digital Designs Audio, famous for their high SPL drivers, use an "8mm in the gap" method. In their opinion, the percentage of coil still in the gap is what matters, rather than the overhang. For DD Audio, this is an important method to consider. They typically use tall top plates and, as such, have very long magnetic gaps that cannot be considered by the traditional overhang method of measurement. Using the overhang method has consistently given DD Audio very low numbers, although most newer and more accurate methods do as well. The issue here is that once the coil begins to move out of the gap, there is a drop in BL, whether there are 8mm of coil in the gap or not. Using DD’s measurement method, this drop in BL would not be accounted for. Due to the large gap that DD uses, this drop is not as drastic as others, but it is a drop in BL regardless. This measurement method also does not cover any of the other issues mentioned with the overhang method.

DUMAX and Klippel
There are two revolutionary measurement systems now available: the DUMAX from Dave Clark and DLC Designs, as well as the Klippel, developed by Dr. Wolfgang Klippel. These measurement systems compare BL with respect to x(mm of excursion). They also consider suspension compliance (Cms) as this will create many of the same issues that a shift in BL will. This is done as 1/Cms (which=Kms) with respect to x(mm of excursion). Both of these demonstrate through a graph the measurement of BL and Cms through both the positive and negative strokes. An example of each graph can be found below:
BL from Klippel
Kms (1/Cms) from Klippel
BL and Kms from DUMAX (scroll down to the graph section)

DLC defines Xmax as the smaller of 1: half of the peak to peak excursion over which BL retains 70.7% of it’s rest position value or 2: half of the peak to peak excursion over which Cms retains 25% of it’s rest position value. These values represent approximately 10% distortion, which is often considered the point of audibility. By using this method, we consider the full flux field as well as the suspension’s limits. Xmag is considered half of the peak to peak excursion of the 70.7% limit for BL, Xsus is considered half of the peak to peak excursion of the 25% limit for Cms, and Xmech is considered half of the peak to peak excursion of the absolute limit of the chassis. The smallest of these 3 values is considered Xmax.

Considering these points is imperative, as BL and Cms distortion accounts for roughly 80-85% of all distortion present in any given driver.

When is linear truly linear?
Dr. Klippel has made a push to consider other factors as well, primarily measuring inductance with respect to x(mm of excursion). This has more to do with how far the driver can be pushed before compromising some level of sound quality, rather than how far the driver can be pushed before compromising excursion. This opens up a possibility to consider cone break up, lead slap, any mechanical noise, air rushing around the basket or pole vent.

The definition of Xmax as defined by the Audio Engineering Society as:
“The voice-coil peak displacement at which the “linearity” of the motor deviates by 10%. Linearity may be measured by percent distortion of the input current or by percent deviation of displacement versus input current.”

On the other hand, Dr. Klippel defines Xmax as such:
“The voice-coil peak displacement Xmax at which either the total harmonic distortion dt or the nth-order modulation distortion (where n=2 or 3) exceeds 10% in the sound pressure radiated by the driver in free air excited by the linear superposition of a first tone at the resonance frequency f1=fs and a second tone f2=8.5 fs with an amplitude ratio of 4:1.
The total harmonic distortion dt assesses the harmonics of f1 and the modulation distortion are measured by the modulation components f2± nf1 according to IEC 60268.”

Summary
With all that said, I personally agree with Dr. Klippel’s definition of Xmax. It considers Total Harmonic Distortion and, as such, seems to closely represent the sonic qualities over excursion. The issue here is that it does not consider Inter-Modulation Distortion and does not necessarily match hearing perception across the board.

To summarize, looking at Xmax can describe potential output while remaining linear, but it is important to understand the application of Xmax and how it is measured. If you see a graph from the DUMAX or Klippel measurement systems, I would be much more inclined to believe the parameters posted. Remember to look deeply into all information provided and that with any audio driver, the whole is greater than the sum of it's parts.

Cheers,
Neil

i only scanned the 1st line or 2 and im gonna say **** this is what ive been sayin for years

the main thing I look at when making driver chocies is Xmax. it is the main reason why I run IB3 drivers. 30mm Xmax 18" for $200, plus a low Fs. I'm not gonna pay more $$$$ for more BL and stiffer spyders when I dont need it. I build my boxes big and tune them low for lower extention, higher efficiency (lower power REQUIRMENT) and smoother wider responce.

I am after the mad infrasonic lows, not the 30Hz-40Hz "lows". This requires excursion. Xmax costs you. If an 06' XXX 18 were $400 I'd run 6 of them instead of the 6 IB3's I have now. If RL-p's were $200, or Maelstrom-X's... those too. But $450 for them gains me nothing at all. On the other end of the spectrum, the IXL Mach 5 18... $200, low Fs.. but only 22mm... not gonna happen either.