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Thread: M2 passive network for CD

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    Senior Member Jakob's Avatar
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    M2 passive network for CD

    Hi,
    I'm searching for the layout of the passive network for the compression driver in the M2. I saw a picture on the forum somewhere but due to the resolution i couldn't read any values on the components. Thanks in advance!

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    Senior Member Odd's Avatar
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    Quote Originally Posted by Jakob View Post
    Hi,
    I'm searching for the layout of the passive network for the compression driver in the M2. I saw a picture on the forum somewhere but due to the resolution i couldn't read any values on the components. Thanks in advance!

    M2 manual
    Attached Images Attached Images
    43XX (2235-2123-2450-2405-CC 3155)5235-4412-4406-4401-L250-18Ti-L40-S109 Aquarius lV-C38 (030) 305P MkII

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    Senior Member Jakob's Avatar
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    Great, thanks for the help!

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    Senior Member audiomagnate's Avatar
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    I'm sure you already know this, but it's not really a passive crossover network, it's just a (compound) blocking cap to protect the D2430K from accidental destruction, and a pair of resistors to pad it down so residual amp noise can't be heard from the listening position under no-signal conditions.

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    Senior Member Jakob's Avatar
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    Yes, i've been playing around for fun with my bss unit and speakers imitating the m2 and just out of curiousity wanted to know how big cap they put in. It seems JBL chose almost the same as me . By the way, I get really enjoyable results with the 6dB high pass at 750 or so Hertz. Digital cross overs and eq is great fun!

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    Senior Member audiomagnate's Avatar
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    Quote Originally Posted by Jakob View Post
    Yes, i've been playing around for fun with my bss unit and speakers imitating the m2 and just out of curiousity wanted to know how big cap they put in. It seems JBL chose almost the same as me . By the way, I get really enjoyable results with the 6dB high pass at 750 or so Hertz. Digital cross overs and eq is great fun!
    With that crossover frequency and gentle slope you're dumping MUCH more mid frequency energy into your driver than goes into a D2.

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    Senior Member Jakob's Avatar
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    Ok, please explain why. If I remember correctly the d2's highpass is a 6dB butterworth set at 782 Hz. What have i missed?

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    Where is that statement from?

    Quote Originally Posted by Jakob View Post
    Ok, please explain why. If I remember correctly the d2's highpass is a 6dB butterworth set at 782 Hz. What have i missed?
    This irritates me, for several reasons. Where is that statement from?

    Ruediger

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    Senior Member pos's Avatar
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    This comes from the DSP preset:
    https://docs.google.com/document/d/1...haring&rm=demo

    The protection networks adds another 6dB/oct high pass filter around 200Hz, and of course the closed volume inside the compression driver also adds is own 12dB/oct high pass.

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    Senior Member Jakob's Avatar
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    Ok, i'm sorry if I'm offending anyone, that has never been my intention
    To clarify; i'm not trying to replicate or clone the m2 but reading about it made me want to experiment with my bss. I'm just having fun, thats all. There is much more to the m2 splendor than a 6 dB filter.

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    No Worries

    No worries, the technical aspects irritated me. I expected a real filter such as Linkwitz, and voila: you can have it. The 6 dB Butterworth is just a partial filter.

    Rüdiger

  12. #12
    Obsolete
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    I expected a real filter such as Linkwitz, and voila: you can have it. The 6 dB Butterworth is just a partial filter.
    The system does have a real filter, acoustic filter coupled with electrical filter. No need to add a bunch of extra poles in the mix and thoroughly jack up the superb system response. In short, the designers have an outstanding handle on world class filter design.

    Quote Originally Posted by pos View Post
    Outstanding!

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    Senior Member pos's Avatar
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    I stumble upon this nos four years old thread, and I think it is important to correct some errors for reference reasons
    It is now known that the schematic of the passive network from the M2 tech manual is false: c1 should read 3.3uF instead of 33.3uF, resulting in a combine c1+c2 value of 8uF, and a first order filter at 1kHz (instead of 209Hz with the original wrong values, quite a difference...)
    And of course you can simply replace c1 and c2 with a single 8uF cap.

    http://www.audioheritage.org/vbullet...l=1#post383264
    http://www.audioheritage.org/vbullet...l=1#post383277

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