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Thread: Project M2 DIY Thread

  1. #661
    Senior Member
    Join Date
    Feb 2018
    Annapolis, MD
    Though I don't think they would make this change, my D2 drivers are genuine M2 versions (gold label with the correct part number). Is there any possibility that they would label the M2 version different from the PA version of the driver?

    I have not made the phase test on the D2 so I'll take you at your word that positive on + makes an inward motion. That would be odd for JBL in the "modern" era. While that was true of JBL product into the '90s, they did make the switch to conform with others such that positive voltage on + would be an outward motion. Those drivers that were directly replacement to legacy drivers would retain the original polarity (e.g. 2446, replaces a 2445 so it keeps the legacy polarity, likewise on a 2241 replacing a 2440 for a cone driver. A 2242, on the other hand, didn't have a legacy driver to match to so it adopted the new standard).

  2. #662
    Member sebackman's Avatar
    Join Date
    Feb 2004

    I agree, it is a bit odd that these new drivers also seem to be "reverse polarity". Attached is the pulse response with reversed polarity, ie positive puls into negative connector. Lower is the output pulse from the amp and upper what the mic picked up. Weird.

    Name:  Pulse D2 reverse polarity.png
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    We also talked about the impedance of the D2 2430K. Here is the raw data from a DATS II impedance sweep on a brand new D2 (with M2 label). The average impedance from 512Hz to 20.643Hz is 26,99 ohms. This is without any passive components, just right out of DATS II. Data files available for those who want.

    Name:  D2 on M2 impedance.jpg
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    Kind regards
    The solution to the problem changes the problem.
    -And always remember that all of your equipment was made by the lowest bidder

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