Apparently I know nothing about T/S

[Smanleyman 15]

So I would really like to learn more about all the T/S parameters and what each affects. I have been searching for a nice 10" at an afordable price and settled on the Fi BL for price and performance, and based on what I thought I knew about subs picked it over the Mach 5 IXL since it has a higher sensitivity and fs and SD I figured its louder. Then I modeled them both in WinISD beta...

The red is the IXL blue is the BL, the lower line is my best attempt on both subs for a daily vented box, basically the flattest response I could get. IXL is flatter and louder... The other line is a 6th order spl box and once again IXL wins... Anyone know why and/or what parameters affect output in what way? Power is the same to all setups. Here are the numbers... The BL is dual 1

DUAL 1 | DUAL 2

Fs: 41.5 Hz | 40.3 Hz

Re: 0.75 Ohms/coil | 1.5 Ohms/coil

Qms: 5.43 | 5.58

Qes: .37 | .44

Qts: .35 | .32

Mms: 155g | 164g

Cms: .95mm/N | .95mm/N

Sd: 310cm^2 | 310cm^2

Vas: 12.8 l | 12.8 l

Spl: 85.8dB 1W/1m | 85.7dB 1W/1m

Bl: 12.8 N/A | 19.0 N/A

Xmax: 21mm

Rms: 1000W *

IXL 10

Power Handling: 1000 Watts

SPL (2.83v/1m): 84 db

Fs = 27.8 Hz

Re = 3.7 Ohms

Qt = 0.43

Qes = 0.46

Qms = 6.44

Mms = 234.1 grams

Cms = 0.14 mm/N

Vas = 13.9 liters

Sd= 265.9 cm2

Xmax = 20 mm

BL = 17.4

Edited December 14, 2008 by fiq15pwnsnoobs

[helotaxi 46]

The output (SPL) plots in WinISD mean exactly dick. The BLs have the potential to be louder, regardless of what the plot tells you. The T/S parameters that you see published pretty much go out the window as soon as you start talking high power applications.

[Thumpper 266]

this will heelp you understand the T/S parameters

Fs------This parameter is the free-air resonant frequency of a speaker. Simply stated, it is the point at which the weight of the moving parts of the speaker becomes balanced with the force of the speaker suspension when in motion. If you've ever seen a piece of string start humming uncontrollably in the wind, you have seen the effect of reaching a resonant frequency. It is important to know this information so that you can prevent your enclosure from 'ringing'. With a loudspeaker, the mass of the moving parts, and the stiffness of the suspension (surround and spider) are the key elements that affect the resonant frequency. As a general rule of thumb, a lower Fs indicates a woofer that would be better for low-frequency reproduction than a woofer with a higher Fs. This is not always the case though, because other parameters affect the ultimate performance as well.

Re--------This is the DC resistance of the driver measured with an ohm meter and it is often referred to as the 'DCR'. This measurement will almost always be less than the driver's nominal impedance. Consumers sometimes get concerned the Re is less than the published impedance and fear that amplifiers will be overloaded. Due to the fact that the inductance of a speaker rises with a rise in frequency, it is unlikely that the amplifier will often see the DC resistance as its load.

Le--------This is the voice coil inductance measured in millihenries (mH). The industry standard is to measure inductance at 1,000 Hz. As frequencies get higher there will be a rise in impedance above Re. This is because the voice coil is acting as an inductor. Consequently, the impedance of a speaker is not a fixed resistance, but can be represented as a curve that changes as the input frequency changes. Maximum impedance (Zmax) occurs at Fs.

Q Parameters---------Qms, Qes, and Qts are measurements related to the control of a transducer's suspension when it reaches the resonant frequency (Fs). The suspension must prevent any lateral motion that might allow the voice coil and pole to touch (this would destroy the loudspeaker). The suspension must also act like a shock absorber. Qms is a measurement of the control coming from the speaker's mechanical suspension system (the surround and spider). View these components like springs. Qes is a measurement of the control coming from the speaker's electrical suspension system (the voice coil and magnet). Opposing forces from the mechanical and electrical suspensions act to absorb shock. Qts is called the 'Total Q' of the driver and is derived from an equation where Qes is multiplied by Qms and the result is divided by the sum of the same.

As a general guideline, Qts of 0.4 or below indicates a transducer well suited to a vented enclosure. Qts between 0.4 and 0.7 indicates suitability for a sealed enclosure. Qts of 0.7 or above indicates suitability for free-air or infinite baffle applications. However, there are exceptions! The Eminence Kilomax 18 has a Qts of 0.56. This suggests a sealed enclosure, but in reality it works extremely well in a ported enclosure. Please consider all the parameters when selecting loudspeakers. If you are in any doubt, contact your Eminence representative for technical assistance

Vas/Cms--------Vas represents the volume of air that when compressed to one cubic meter exerts the same force as the compliance (Cms) of the suspension in a particular speaker. Vas is one of the trickiest parameters to measure because air pressure changes relative to humidity and temperature

[Smanleyman 15]

Thanks thumper very good info...

So you think the BL will definitely be louder? I intend to build a sixth order spl box and a daily box for any sub I get, so Im looking for the loudest daily setup I can get while being relatively flat... The BL daily box is within +/- 1db from 27-66hz according to winISD which is fine for me doesnt need to be perfect...

[NB50 206]

Remember that response is assuming an infinite environment. So the response is going to change as so as you put it in a car.

[Smanleyman 15]

Well I dont know my cars peak... how many DB typically is a cars peak over the rest...? Would a curve like that of the bl daily be good since cars tend to peak 40s-50s so have it lowest there and let the car even it out?

[95Honda 486]

I think most of it has do with the IXL's larger Vas, everyhting else being somewhat equal, this is where your efficiency boost is coming from...