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Thread: Thiele/Small Parameters

  1. #1
    Niklas Nord
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    Thiele/Small Parameters

    On several sites there are parameters for the JBL drivers,
    i can se that some values are different.

    Do anyone know a reliable source list of the parameters.

    Something i was thinking of right now, was the sensitivity of:

    2202H
    2123H
    2235H
    2234H
    2245H

    I cant find a reliable answer anywhere.

    WHY is there no PDF on the 2234, i really do not like
    the JBL webpage, it makes me angry all the time..


  2. #2
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    Re: Thiele/Small Parameters

    Because the 2234H was designed specifically for the 4435; it wasn't to be sold as part of the regular transducer line.

    The most reliable scource for TS parameters are obtained by measuring your particular transducers. Measure them perhaps ten times each over a period of a few weeks and then average the results. Temperature, humidity, barometric pressure, etc. all affect a transducer's TS parameters. What you measure on Tuesday in Brussels, Belgium won't be what you measure on Wednesday in Leadville, Colorado. All the transducers you have listed above, along with their "typical" TS parameters, can be found on the JBL Pro website.

    Looking at the 2202H Spec Sheet from JBL I noticed they have the effective piston diameter as 280mm / 10.25in. According to the TS parameters that effective piston diameter has to be 260mm / 10.25in so there's one misprint. Here is a list of reasonably "good" parameters:

    2202H

    Fs = 50 Hz
    Qms = 3.5
    Vas = 89 liters
    Cms = 220 Ám/N
    Mms = 46.06 g
    Rms = 4.134 mohms
    Xmax = 3.5 mm
    Xmech = 7 mm
    P-Dia = 260.4 mm
    Sd = 0.053 sq.m
    P-Vd = 185.5 cu.cm
    Qes = 0.17
    Re = 5.5 ohms
    Le = 1.1 mH
    Z = 6.6 ohms
    BL = 21.63 Tm
    Pe = 150 watts
    Qts = 0.16
    no = 6.223 %
    1-W SPL = 100.1 dB
    2.83-V SPL = 101.7 dB

    2123H

    Fs = 85 Hz
    Qms = 2.5
    Vas = 19.82 liters
    Cms = 139.7 Ám/N
    Mms = 25 g
    Rms = 5.361 mohms
    Xmax = 2.54 mm
    Xmech = 5.08 mm
    P-Dia = 200.7 mm
    Sd = 0.0316 sq.m
    P-Vd = 80.28 cu.cm
    Qes = 0.37
    Re = 4.2 ohms
    Le = 0.4 mH
    Z = 8 ohms
    BL = 12.3 Tm
    Pe = 250 watts
    Qts = 0.32
    no = 3.2 %
    1-W SPL = 97.16 dB
    2.83-V SPL = 100 dB

    2245H

    Fs = 20 Hz
    Qms = 2.2
    Vas = 821.2 liters
    Cms = 347.3 Ám/N
    Mms = 185 g
    Rms = 10.42 mohms
    Xmax = 9.5 mm
    Xmech = 12.7 mm
    P-Dia = 406.4 mm
    Sd = 0.129 sq.m
    P-Vd = 1230 cu.cm
    Qes = 0.31
    Re = 5.8 ohms
    Le = 1.4 mH
    Z = 8 ohms
    BL = 21 Tm
    Pe = 300 watts
    Qts = 0.27
    no = 2.1 %
    1-W SPL = 95 dB
    2.83-V SPL = 96.77 dB

    **********

    See:

    http://www.audioheritage.org/vbullet...ight=2234+2235

    for the 2234H and 2235H parameters.
    Last edited by 4313B; 07-11-2003 at 01:40 PM.

  3. #3
    Niklas Nord
    Guest
    Thank you Giskard.

    I think you said one time ago, that the FS of the 2235 and
    2245 will go down to something like 16 and not 20.

    I can imagine this is due to the suspension and spider,
    are being more soft as it should be.

    Should we don┤t take this in calculation when designing a box
    for the driver? Maybe, after some hundred hours or so, we
    end up with a driver with a FS of 16 and not 20, all the
    parameters has changed, and NOW we has this box, that is
    not so wery well suited anymore.
    :o

    Do i have a point here?

    Has anyone been measuring the drivers, drivers that has been
    in some use, has the parameters been changed?

  4. #4
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    "On several sites there are parameters for the JBL drivers,
    i can se that some values are different.

    Do anyone know a reliable source list of the parameters."


    Ha! Ha! Ha!

    There was an error in the 2234H TS parameters posted above. See:

    http://www.audioheritage.org/vbullet...ight=2234+2235

    for the 2234H and 2235H parameters.

    "Has anyone been measuring the drivers, drivers that has been
    in some use, has the parameters been changed?"


    Yeah, they change over time with use or disuse. Spiders sag, magnets demag, surrounds degenerate, etc. It's all part of that "maximum randomness" crap. That's why you should uncomplicate your life, toss your old JBL's in the trash or eBay them, and buy K2-S9800's. Those will be good for another 20 to 30 years

    "Should we don┤t take this in calculation when designing a box
    for the driver? Maybe, after some hundred hours or so, we
    end up with a driver with a FS of 16 and not 20, all the
    parameters has changed, and NOW we has this box, that is
    not so wery well suited anymore."


    No. Maybe you are trying to be a bit too exact? Most JBL transducers are pretty tight in their tolerances, especially if you compare them to less stringently manufactured transducers. A few Hz here, a few Hz there, who cares? No different than the tolerances of the average passive network components.
    Besides, I think a 5.0 cubic foot enclosure tuned to 30 Hz pretty much dominates a 2235H. I don't think it matters too much if one of the 2235H's has a measured Fs of let's say 16 Hz and the other has a measured Fs of let's say 19 Hz. Just keep your enclosure Fb as tight as possible. I believe the tolerances of the transducers such as the 2235H are plus or minus 5%. You may want to read D.B. Keele's paper on parameter variations. Im sure it's available from the Audio Engineering Society.
    Last edited by 4313B; 07-11-2003 at 01:45 PM.

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