[French projet] Which TD12 ?

Posted In: Subwoofers 101


  • Participant
    Cobrasse on #1338

    Hi,

    I’m french, so i apoligize for my bad english, I tried to explain myself as well as possible 🙂

    I researh a 12 inch speaker for my project :

    – Bandwidth to link a beyma CP755-Ti compression driver on 18sound XR1496 somewhere around 800Hz or 1 KHz.
    – A SPL about 105dB at 1 meter in a sealed box with linkwitz transform to touch 40Hz or 45Hz at -3dB
    – An excellent amortization, with not important dips after filtering
    – A reduce distorsion even the extended low frequency caused by the Linkwtiz transform
    – A cost smaller than 350€ delivery included

    I so different measurements on the web (TD12M : https://sites.google.com/site/drivervault/driver-measurements/tang-band-75-1558se/ae-speakers-td12m to example). We can see break-up/dips at 2KHz, like a PHL 4021 who is a direct opponent (http://lsv-achenbach.de/shop/images/kt_test_phl-b30-4021.jpg). Do the X or H model have the same behavior in mid and High frequency ?

    The TD12’s doesn’t have vented gap cooling, and it’s the plug and others hole who cooled the coil ! But what are the driver performance in heat dissipation (power compression ?) ?

    How the Xmax is evaluated ?

    I’d like to hear comments that confirm my assumptions about the linearity, amortization and distortions with respect to the use I expect.

    Thank’s for the answer

    Best regards 😉


    Participant
    stryke on #11303

    Hello,

    If you take a look at response curves at 0, 20, and 40 degrees you see that the TD12M extends cleanly to over 4KHz. All other drivers measured there have much more breakup. The difference is that we have very low inductance so the response is electrically flat much higher in frequency. Others rely on cone and dustcap breakup to provide the upper end sensitivity which means very high distortion.

    In reality a 12″ is going to go up to about 1200hz maximum as it narrows to less than 90 degrees at that point. If going only to 800-10KHz then the TD12S, X, or H could also be used. They have good response up into that region as well.They will provide less efficiency but much more Xmax for the low end.

    The TD woofers cool differently than a vented pole. The vented pole does not push heat out well because the air flow is bidirectional. Air moves back and forth in the vent but never totally exits keeping the heat inside. With the TD woofers, heat from the windings is pulled into the aluminum former right away. The aluminum former is over 2″ long and in very close proximity to the copper sleeve on the pole. This copper sleeve quickly pulls heat from the coil former and sinks it into the large steel pole. This happens much more quickly than with normal air cooling from a vented pole. From there the phase plug pulls heat from the pole. The motion of the cone helps to cool the phase plug. This is a much better heat transfer method than through air vibrating back and forth in a vented pole.

    Xmax was evaluated based on the Bl curve and 30% drop in Bl as per Klippel standards.


    Participant
    Cobrasse on #11302

    Hi, Thank’s for the answer,

    The TD12X or TD12H are usable for my project

    how much measure the Height Gap and the height coil on these speakers ?

    How do you proceed to send the speaker to France ? How much the price of the speaker + shipping ?

    Have a good day

    PS : There are in the top 3 for my project 😀 . The total cost determines my choice.


    Participant
    stryke on #11304

    You will find it very hard to find something else with equivalent efficiency, low Le, low distortion, and extended frequency response at any cost. These have a very thick gap plate at 19mm and 38mm long coil. This gives just under 10mm overhang and Bl curve verifies over 14mm Xmax.

    The PHL specifically has a massive breakup at 2KHz. At 0 degrees you can see a large bump and by 45 degrees it has become a very large dip. Even though this is not in the intended bandwidth it will be a significant problem. Looking at the waterfall plot shows this extends very long in time. I would not use this driver above 500hz at the most to keep this issue from being audible. Crossing at 250hz is more ideal for the PHL.

    you can email Jessica, info(at)aespeakers.com and she can get you a quote for the woofer and shipping.


    Participant
    Cobrasse on #11305

    Hi

    @stryke wrote:

    You will find it very hard to find something else with equivalent efficiency, low Le, low distortion, and extended frequency response at any cost. These have a very thick gap plate at 19mm and 38mm long coil. This gives just under 10mm overhang and Bl curve verifies over 14mm Xmax.

    Argh ! This is a huge xmax.

    How does the spider and suspension with such travels ? I see some klippel test : http://medleysmusings.com/category/speaker-driver-tests/midwoofers/

    And the curve of Cms & Kms are like this :

    http://medleysmusings.com/wp-content/uploads/2014/03/Mechanical-compliance-Cms-X.png

    http://medleysmusings.com/wp-content/uploads/2014/03/Stiffness-of-suspension-Kms-X.png

    or it has offset’s flaw et non linearity ?

    The PHL specifically has a massive breakup at 2KHz. At 0 degrees you can see a large bump and by 45 degrees it has become a very large dip. Even though this is not in the intended bandwidth it will be a significant problem. Looking at the waterfall plot shows this extends very long in time. I would not use this driver above 500hz at the most to keep this issue from being audible. Crossing at 250hz is more ideal for the PHL.

    Yes, but le TD12M break’s too around 2 khz : https://sites.google.com/site/drivervault/driver-measurements/tang-band-75-1558se/ae-speakers-td12m/frequency-response/CSD.PNG?attredirects=0

    I know that PHL favors a very good damping before the big break, like aluminium’s cone

    you can email Jessica, info(at)aespeakers.com and she can get you a quote for the woofer and shipping.

    thank’s

    Best regards.


    Participant
    stryke on #11306

    The two curves are not very comparable. The waterfall for the TD12M goes out to 3ms and shows a decay from 85dB to 45dB, 40dB total drop on the scale. You can see that the decay at 2KHz is very close to the same as it is at 200hz. It is dropping by over 30dB by this 3ms point.

    In comparison, the PHL goes out to 6ms and shows only a 25dB scale. While everything else has decayed the 2KHz resonance is still going very long. At 6ms it has only dropped 25dB which is over twice as long as the TD12M at that point. At 3ms in, the 2KHz resonance has only dropped about 10dB. This is very problematic.

    The TD12X and TD12H have suspension that is good to about 22mm total travel. At 14mm Xmax the suspension has not changed much in terms of stiffness. It is designed to be quite linear within Xmax as well.


    Participant
    Cobrasse on #11307

    Hi,

    Thank’s, I like your answers 😉 .

    if you were in the same situation as me to this project, you choose the H, X or S (perhaps the M with xmax +/- 6mm is enough for my application and if it’s high reponse in high frequency is really better I can choose it !)… ? They are similarities, but in high frequencies who’s the better ? They are the same cone, the difference of weight is just the mass of the voice coil, no ?

    Should be favor a High Bl ?

    The Qms is the mechanical’s lost, I heard that higher is better. Your opinion on it ?

    Best regards


    Participant
    stryke on #11308

    The TD12M does have better high frequency extension. If used in a sealed box, the TD12M at the 6mm Xmax will give about 105dB at 40hz with 175W input. If you feel this is enough then the TD12M could work just fine. The TD12S could input about 700W at 40hz reaching 113dB at the 14mm Xmax. It depends though on how much power you have to apply and the levels you wish to get. The TD12M does have more efficiency and better high end extension because of the lighter cone and cloth surround vs foam. If the upper end extension is your priority the TD12M is the better option.

    Bl by itself is not a meaningful value. This determines the application for the driver, enclosure volume, tuning, etc. Higher or lower Bl doesn’t necessarily mean the woofer is better or worse, it only determines what alignment it should be used in. Higher Qms in theory is good, but is not very significant vs the damping of the full system in the enclosure. It is again only a part of determining the best alignment for the woofer.


    Participant
    Cobrasse on #11309

    Thank’s,

    So, i think that the TD12M is the best way for me … It’s for home application in a living room !

    I do have concerns about the distortion in low frequency ? I see important H2 on this picture under 100Hz :

    https://sites.google.com/site/drivervault/driver-measurements/tang-band-75-1558se/ae-speakers-td12m/non-linear-distortion/HD_sweep.PNG?attredirects=0

    Only + version have ring to reduce distorsions ? No 12″ is equiped ?

    I apologize for all this question. But it comforts more my choice 😉

    Best regards


    Participant
    stryke on #11310

    H2 distortion is not related to the motor itself. This is more physical based on spider and surround. The drivers that measure better have much higher excursion suspension.

    Shorting rings are more effective higher in frequency. To have them be effective down lower they need to get much larger and thicker. We simply can’t open the gap more to add more copper or the efficiency will drop quickly. At lower frequencies the copper has less effect than at the higher frequencies where most woofers have much more distortion. It also affects the odd order harmonics which are motor related. Look at H3 and H5 distortions for the B&C 12HPL76. Then compare to the TD12M. There is a massive difference in the H3 and H5 distortions that you will see.


    Participant
    Cobrasse on #11311

    Hi,

    Thank’s for the anwser.

    So no regrets takings the M version to reproduce 40Hz/45Hz to 800Hz bandwith at 105dB/2.83volts/m, with lowest distorsions as possible, lowest damping as possible …

    If the X version is as good as the M version until 800Hz, I prefer the model who have the better xmax !

    Your conclusion will be my choice 😉 .

    Thnak’s a lot for your kindness and your time.

Viewing 11 posts - 1 through 11 (of 11 total)

You must be logged in to reply to this topic.