Help with weird T/S parameters.

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saikomorisan

Member
Joined 2019
#1
Hello everyone, I recently bought a Kruger Matz 15" km380t11 subwoofer I found its datasheet but things are strange at first I thought it was because everything is in Polish but soon I realize that some units are completely wrong or i think so.

These are the given parameters.

Revc: 3.4 Ohm
Fo: 29.025 Hz
Sd: 70.686 cm
Md: 200.410g
BL: 9.803 Tm
Qms: 5.798
Qes: 1.328
Qts: 1.081
No: 0.184%
SPLo: 84.7 dB
Vas: 103.609m M
Cms: 146.030u M/N
Krm:5.036 mOhm
Erm: 0.843
Mms: 205.893g
Mmd: 195.087m Kg
Kxm: 24.497mH
Exm: 0.649

so if someone is able to help me to understand what is going on i will greatly appreciate it thanks for you time.
I left the original pdf in the attachments.
 

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#2
Sd should be approx. 880 cm^2 for a 15" woofer, so I think it should be 706.86 cm^2.

Try with these parameters
Re: 3.4 Ohm
Fs: 29.025 Hz
Sd: 706.86 cm^2
BL: 9.803 Tm
Qms: 5.798
Qes: 1.328
Vas: 103.609 L

Assuming car audio use, music: the high Qts suggests that an infinite baffle works best. If that is not possible, a closed box will work OK-ish. Just looking at Qts, fs and Vas and the intended application, a box of 100 L seems like a reasonable compromise between performance and size.
 
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#3
TBTL said:
Sd should be approx. 880 cm^2 for a 15" woofer, so I think it should be 706.86 cm^2.

Try with these parameters
Re: 3.4 Ohm
Fs: 29.025 Hz
Sd: 706.86 cm^2
BL: 9.803 Tm
Qms: 5.798
Qes: 1.328
Vas: 103.609 L

Assuming car audio use, music: the high Qts suggests that an infinite baffle works best. If that is not possible, a closed box will work OK-ish. Just looking at Qts, fs and Vas and the intended application, a box of 100 L seems like a reasonable compromise between performance and size.
Click to expand...
thanks for the help well i will try it, and wich do you think is the xmax i think may be this "Kxm: 24.497mH" but in mm of course
 
#4
Sorry no; so being a mobile audio woofer the actual manufacturers too often either don't publish Xmax or it's somewhat 'optimistic', then short of doing Klippel measurements this is AFAIK about the best a DIYer can do without doing high power distortion limits using one's hearing: Wedge Micrometer
 
#5
GM said:
Sorry no; so being a mobile audio woofer the actual manufacturers too often either don't publish Xmax or it's somewhat 'optimistic', then short of doing Klippel measurements this is AFAIK about the best a DIYer can do without doing high power distortion limits using one's hearing: Wedge Micrometer
Click to expand...
i see, well appreciate the info, will try to build the box with available info, cannot be worse than not having any info
 
#6
You're welcome! True, especially since the T/S specs tend to be pretty far off on inexpensive drivers. 🙁 Fortunately though, 'cabin gain' combined with today's DSP capability ameliorates it to a great extent. Note too that its base power rating is only 300 W, indicative of a very modest Xmax by today's standards, so an acoustically small sealed box is a good choice.

edit: Since its usable BW is listed out to 1 kHz is indicative of a low inductance, a quick search of similar spec drivers turned up a Le = 0.4 mH, so thermal power distortion should be minimal.
 
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#7
saikomorisan said:
thanks for the help well i will try it, and wich do you think is the xmax i think may be this "Kxm: 24.497mH" but in mm of course
Click to expand...
Not related to Xmax

It is impedance fitting constants..... not very common for data sheets

Kxm = Frequency dependent reactance


They do not list Xmax or Height of Gap
or Height of coil
so Xmax is a Guessing Game

BL or Force Factor is calculated from B = Flux Density and L = length of coil

So there might be a way to cross calculate those numbers.
That would only give you the length of the coil though.
Which would narrow down the Xmax guess
 
#12
TBTL said:
Are you planning on using it in a car?
Click to expand...
No, it is a sub for my room kinda home theater, i know tha this sub aint nothing close to ideal for home theaer sub but i have no choise where i live the type of subs sold are like "jbl selenium tornado" wich FS are high aprox 37hz to 45hz and very limited xmax, while it fits for the type of music popular here not usefull for low freq respose, so i end up with limited choises, there are better opcions like the best i found an 18" focal sub but over a 1500usd or kickers mtx way overpriced due to high taxes and shiping. now making various test in winisd and bassbox pro. any ideas or recommendations are appreciated.
 
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