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Old 16th August 2007, 12:48   #16
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lika all of us i am here to learn.its just that i had a doudbt so wantin to know.
lets take IDQ.probably amongst the best sounding woofers.hats off to the people of ID.one listen and i was blown away.absolute nirvana.imo all over the world it is considered as some of the BEST SQ subwoofers.for SQ-SQL i think its the mighty IDMAX which ranks amongst the best .idq has xmax of 13.8 and rms power handling of 350-400w.if supposing we increase the xmax of idq to 25mm what will happen to sound.
is there any TRUE SPL subwoofer with an xmax of 10-15mm.(12'ers).at the end of the day its the amount of mass OF AIR MOVED WHAT WE PERCIEVE AS sound.
sorry gurus for such stupid question.

Last edited by zucchero : 16th August 2007 at 12:50.
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Old 16th August 2007, 12:51   #17
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Can you feel the taste and quality of Movenpick peach melba by just reading the ingredients? I will ask for a sampling spoon rather than oogling and comparing.

I hope same thing works for ICE too. Any speaker it may be, ears are the best way to judge it's tonal quality.

OT,
What is watts and SQ/SPL doing here? Why confuse matters?
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Old 16th August 2007, 12:53   #18
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Quote:
Originally Posted by zucchero View Post
ok lets put up this way if its comparing each other.there are two subwoofers with almost same parameters,sensitivity,power handling...etc,etc the enclosure volume of both are same.the only difference is in the excursion.one has a xmax of say 15mm and the other 25mm.what and where will the difference be????
it will be close to impossible for 2 woofers to have all the same parameters and only different Xmax. Once the Xmax changes, the Cms will change, the Cms changes the Qms will change, etc....

Assuming ALL the parameters are the same (save Xmax) and that includes Bl, Cms, etc... (there are about 20 odd parameters that are usually measured) what Xmax states is really how far the cone can move. there is Linear Xmax and Max Xmax either of which can be stated as one way or peak to peak. So lets assume there are 2 woofers that have ALL the same parameters (almost impossible but but we are being hypothetical) same but one has a Linear one way Xmax of 15mm and the other has a linear one ay Xmax of 25mm. What this tells you is that the second woofer will move 60% more air and hence play a little louder (given adequate amplifier power) than the first woofer.

See if you can find old copies of "Voice Coil". It was an excellent mag (sub mag of Speaker Builder) and VC discusses a lot aout transducer design.
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Old 16th August 2007, 13:02   #19
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exactly navin ji this is what i am saying.the one with the greater xmax will platy louder.assuming that all the subs are 12 inchers USUALLY the one with greater xmax will be loud.
for pure SPL purposes would it be not advisable to go for higher xmax subwoofers as they will dislpace more air and hence sound.
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Old 16th August 2007, 13:06   #20
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2 different subwoofers (different brands, models) with the same Xmax will sound totally different. You cannot generalize sound reproduction.
If you could, then this entire ICE section is pointless.
All we would do, is post a bunch of parameters and lock the forum.
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Old 16th August 2007, 13:09   #21
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Hmmm..the Fi has there top model BTL which is a spl sub and the XMAX is 16 mm and the wattages is 2000 watts rms.

https://ssl.perfora.net/www.ficaraud...iew.shopscript

Also the IDMAX is a SQ sub which can do good SPL. No doubt in that..

firstly what is XMAX ?

Specified in millimeters (mm). In the simplest form, subtract the height of the voice coil winding from the height of the magnetic gap, taking the absolute value and dividing by 2. This technique was suggested by JBL's Mark Gander in a 1981 AES paper, as an indicator of a loudspeaker motor's linear range. Although easily determined, it ignores non-linearities and limitations introduced by the suspension. Subsequently, a combined mechanical/acoustical measure was suggested, in which a driver is progressively driven to high levels at low frequencies, with Xmax determined at 10% THD. This method better represents driver performance.

Taken from wiki. Thiele/Small - Wikipedia, the free encyclopedia

The Subwoofer Conundrum

Here is a graphic illustration of the same.

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Old 16th August 2007, 13:09   #22
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Quote:
Originally Posted by zucchero View Post
ok lets put up this way if its comparing each other.there are two subwoofers with almost same parameters,sensitivity,power handling...etc,etc the enclosure volume of both are same.the only difference is in the excursion.one has a xmax of say 15mm and the other 25mm.what and where will the difference be????
sorry if i am being stupid
The difference is a pointer to the peak handling without the voice coil hitting the limits and making slapping sounds of it's own!

Really not easy to predict when this happens and under what circumstances (depends on the music being played). Loosely, this will happen when
- either the power being pushed through the amp is at the limit of the rated power of the sub (better to power it with a lesser capability amp than the sub's rating - the distortion will make it painfully evident to the listener that things are not right)
- or the combination of the dynamics of the music and amp pushes current too fast for the sub to handle (similar to wheel spin; difficult to compute and control; generally a good sealed box would damp it because of the air behind the cone)

So, generally and loosely, the higher Xmax would be a pointer to less likelihood of things becoming unmusical (or unhealthy on the pocket) in extreme circumstances.

BUT, it is likely, as the others have pointed out, that even with the higher Xmax the sub may not be musical under normal circumstances - not everything can be explained using data sheet parameters.
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Old 16th August 2007, 13:09   #23
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sam sir,the xmax as you said is not the SAME.i suppose you are not gettin my point sir.
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Old 16th August 2007, 13:13   #24
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No baba, you are not getting my point. You cannot judge the sound of any subwoofer, no matter what you read.
Xmax or anything.

I can show you a woofer with low Xmax that sounds like crap and one with high Xmax and it still sounds like crap. So what good are you spec sheets going to do?

Spec sheets serve as a GUIDE only. A guide to building enclosures etc. They do not represent the sound quality of a speaker.
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Old 16th August 2007, 13:17   #25
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Quote:
Originally Posted by zucchero View Post
exactly navin ji this is what i am saying.the one with the greater xmax will platy louder.assuming that all the subs are 12 inchers USUALLY the one with greater xmax will be loud.
for pure SPL purposes would it be not advisable to go for higher xmax subwoofers as they will dislpace more air and hence sound.
Let us take this example...

BTL12 (SPL MODEL)

DUAL 1 | DUAL 2 Fs: 40.7 Hz | 39.8 Hz Re: 0.7 Ohms/coil | 1.5 Ohms/coil Qms: 4.91 | 5.03 Qes: .22 | .21 Qts: .21 | .20 Mms: 191g | 201g Cms: 0.80mm/N | 0.80mm/N Sd: 480cm^2 | 480cm^2 Vas: 25.7 l | 25.7 l Spl: 90.7dB 1W/1m | 90.7dB 1W/1m Bl: 17.5 N/A | 26.9 N/A Xmax: 16mm * | 16mm Rms: 2000W * | 2000W * Sealed box: N/A cuft | N/A cuft Ported box: 1.75-3cuft | 1.75-3cuft Sub OD: 12.500” | 12.500” Cut ID: 11.125” | 11.125” Mounting depth: 6.750” * | 6.750” * Displacement: 0.18cuft * | 0.18cuft *

and this one...

Q12 (SQ MODEL)

DUAL 1 | DUAL 2 Fs: 28.4 Hz | 27.1 Hz Re: 0.7 Ohms/coil | 1.4 Ohms/coil Qms: 05.39 | 5.63 Qes: .49 | .48 Qts: .45 | .44 Mms: 211g | 231g Cms: 0.15mm/N | 0.15mm/N Sd: 481cm^2 | 481cm^2 Vas: 48.3 l | 48.3 l Spl: 85.4dB 1W/1m | 84.8dB 1W/1m Bl: 10.4 N/A | 15.1 N/A Xmax:27mm Rms: 1000W Sealed box:.8-1.5 cuft Ported box:1.8-2.5 cuft @ 28-33Hz Sub OD: 12.500” Cut ID:11.125” Mounting depth: 7.000” Displacement: 0.16cuft

Now check the senstivity and the xmax and thermal handing of the two subs and tell which one can go loud.

Last edited by low_bass_makker : 16th August 2007 at 13:19.
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Old 16th August 2007, 13:24   #26
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Quote:
Originally Posted by DerAlte View Post
The difference is a pointer to the peak handling without the voice coil hitting the limits and making slapping sounds of it's own!
Not really. Xmax of a driver is no indication of how much power it can take.It just indicates a motor design for higher excursion, i.e. more bass without a larger radiating area.
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Old 16th August 2007, 13:37   #27
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Quote:
Originally Posted by Bass&Trouble View Post
Not really. Xmax of a driver is no indication of how much power it can take.It just indicates a motor design for higher excursion, i.e. more bass without a larger radiating area.
The allusion to "Peak" (maximum excursion; Xmax is the "safe" value, but the physical limit is higher?) was relative to "whatever is the declared power" of the sub, not to *how much absolute power*.

Also, isn't the actual displacement not proportional to di/dt of the current going through the VC? I had read somewhere JBL licked that problem in SPL subs by going 'servo'.
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Old 16th August 2007, 13:52   #28
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Quote:
Originally Posted by DerAlte View Post
The allusion to "Peak" (maximum excursion; Xmax is the "safe" value, but the physical limit is higher?) was relative to "whatever is the declared power" of the sub, not to *how much absolute power*.

Also, isn't the actual displacement not proportional to di/dt of the current going through the VC? I had read somewhere JBL licked that problem in SPL subs by going 'servo'.
Your posts have started to bear an uncanny resemblance to Navin's in the sense that they have me miserably confused due to my own shortcomings.

Navin, can you please run an IP check to confirm that you are not posting under this assumed handle.

I meant to say that even though a sub may have a linear Xmax of 50mm, it may travel peak to peak with as low as 10 watts and as much as 1000 watts. I hope that is what you were trying to explain.
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Old 16th August 2007, 13:57   #29
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Quote:
Originally Posted by navin View Post
one has a Linear one way Xmax of 15mm and the other has a linear one ay Xmax of 25mm. What this tells you is that the second woofer will move 60% more air and hence play a little louder (given adequate amplifier power) than the first woofer.
Quote:
Originally Posted by zucchero View Post
exactly navin ji this is what i am saying.the one with the greater xmax will platy louder.assuming that all the subs are 12 inchers USUALLY the one with greater xmax will be loud.
for pure SPL purposes would it be not advisable to go for higher xmax subwoofers as they will dislpace more air and hence sound.

Not necessary..I agree that sub with larger xmax will be louder one, But it does not mean it will change the SQ or tonal quality of the sub..

here is one more SPL sub with 10 mm Xmax which is also a world record holder.. Pioneer 5000 spl.



Pioneer Electronics - Sound. Vision. Soul
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Old 16th August 2007, 14:01   #30
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is it possible to know that wether a woofer is an SQ or SPL going by the xmax is what i wanted to know??
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