then mustang what do u supose gives a subwoofer a different frequencie and dont say box size cuz every sub has a different box size to max performance so there for it is a combo of cone materal and size
Many different variables actually.
Vas
Fs
Qts
Bl
are just some of the things that effect frequency response...
Fs - Free air resonance
Qts - Overall "Q" of the driver
BL - Force in tm (tesla meters) that is exerted on the coil
Vas - Suspension compliance in Liters
Ok...so you have a subwoofer like a MTX RFL with an FS of 62Hz, a Q that is rather low (around .28 if i recall correctly) and a response that just peaks from high hell. This woofer has about the same radiating area of a JL 13w7, but yet it does not have the same frequency response? How's that so...they are the same size right? The RFL Peaks from high hell due to the way it is designed, It is known as a Midbass driver on crack. It is NOT made to play below 60Hz. It's a little bit bigger then the 13w7..why won't it play lower then it????
Ok. A mid Q driver (.35-.55 normally is what i use as a rule of thumb, others may differ but that's their opinions) (like the w7) has a milder Bl curve, and is typically parabolic in nature. These are typically the best all around woofers in my opinion. Generally a well designed driver has a Q of around .35ish and a Fs that is reasonable in/or around the Upper 20's to low 30's. This is just something that i like personally, and is bascially personal taste.
Ok now..time for education.
Take a 18" Kicker Solo X - Here's the parameters
Manufacturer: Kicker
Model: Solo X 18" dvc 1 ohm
Filename: SOLOXD1.UNT
Speaker type: Bass
Sd: 1426.00 cm^2
Vas: 185.64 l
Cms: 6.52e-05 m/N
Cas: 1.33e-06 m^5/N
Mmd: 817.76 g
Mms: 848.22 g
Rms: 12.90 Ns/m
Fs: 21.4 Hz
Bl: 31.21 N/A
Re: 2.05 ohm
Le: 0.00 mH
Qms: 8.84
Qes: 0.24
Qts: 0.23
Pmax: 5000.0 W
Xmax: 24.00 mm
Ok..Here we go.
Vas - on this particular driver it is VERY high, this tells me that the suspension on this woofer is VERY VERY VERY stiff. (Typically a woofer like a brahma or a w7 has around 35-40 liters if i recall correctly, if i'm a little off i'm sorry Dan, but that's not the point of this. Ok - very stiff suspension...Why you ask?
Kicker has designed a VERY powerful motor (This is where the Q and the BL come into play) To keep the soft parts under control they had to use a very stiff suspension. Typically adding a stiff suspension to a woofer such as this with a low Qts (.23) would make the Fs shoot through the roof right? You've created a midbass driver on crack!
However - This 18" square woofer has an Fs of 21.4Hz. Why so low you ask? They had to mass the heck out of the cone (848.22 grams is INSANE for a moving mass...but they have a reason for this, ill get that in a minute) Typically Moving mass for a woofer is at or around the 300 gram mark, Even then 300 grams can be considered 'Heavy'. Back to how they got such a low Fs. They got a low Fs by massing the cone, Bringing the Qts up (from .13 if i recall correctly, to a more manageable .23) In sense it has 'mellowed out' the driver. By mellowing it out it makes it more pleasent to the listeners ears, it does not peak near as hard and it doesn't peak as high.
Bigger radiating cone area doesn't mean it will play lower. If Kicker did not add all of that moving mass to the cone/soft part assembly you would NOT beable to get the Solo X 18 Dual 1 to play under 65-70Hz period. The following model is the EXACT same woofer (Solo X 18 Dual 1) modeled with 330 grams of moving mass. Look how many of the parameters have changed. It's the same woofer, same radiating cone area same EVERYTHING. Except Moving Mass.
Manufacturer: Kicker
Model: Solo X 18" dvc 1 ohm
Filename: SOLOXD1.UNT
Speaker type: Bass
Sd: 1426.00 cm^2
Vas: 185.64 l
Cms: 6.52e-05 m/N
Cas: 1.33e-06 m^5/N
Mmd: 300.00 g
Mms: 330.46 g
Rms: 12.90 Ns/m
Fs: 34.3 Hz
Bl: 31.21 N/A
Re: 2.05 ohm
Le: 0.00 mH
Qms: 5.52
Qes: 0.15
Qts: 0.15
Pmax: 5000.0 W
Xmax: 24.00 mm
Your Q's are MUCH lower, Your Fs is much higher. This isn't as much of a DRASTIC change that i wanted to show you an example of, if i can get the program to work ill post again and update it.
And I rest my case...I hope you read this and possibly learn something...
-Nick
