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Thread: JBL 2360 - new install

  1. #31
    Senior Member macaroonie's Avatar
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    Thats Mark Gander. He created the Cabaret series which kinda set JBL on its path to being as big as it is in pro / tour/ live sound

  2. #32
    Senior Member Lee in Montreal's Avatar
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    Quote Originally Posted by macaroonie View Post
    Thats Mark Gander. He created the Cabaret series which kinda set JBL on its path to being as big as it is in pro / tour/ live sound
    And he kept the pony tail. I love California. ;-)

    Early 1980s I think.


  3. #33
    Senior Member ivica's Avatar
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    Quote Originally Posted by macaroonie View Post
    Lee have you been hibernating. The D2 works in a totally different fashion to the BMS. The BMS is a two way coaxial comression driver. It has a 3" MF annular dia and a 1.75" dome dia , passive crossover somewhere in the mix I assume.

    The JBL D2 has two annular dias that work like this and the air in between is collected and fed to the phase plug and out to the waveguide.

    See here http://www.audioheritage.org/vbullet...-Monitor/page6
    post 88 for a cross section.

    If you have genuinely missed all the hoo ha about this read the whole thread and then go to the JBL pro site and get the skinny and then you tube anything you can find about the VTX series line arrays. They use 3 D2's per box and the field reports are glowing with praise.
    Hi macaroonie,

    Just to be MORE PRECISE: BMS 4590/92 has TWO annular diaphragms too,
    but with different purpose:
    one larger for mid section ( 3.5-inch vice coil), and
    one smaller (1.75-inch) annular (NOT DOME type) for high section,
    as can be seen on the attached figures.
    They are working 'independently' with their 'own' phase plugs, but with 'common' short horn, while JBL D2 diaphragms are intended to be used to work 'together' (compound).....

    But for either of the drivers it would be very difficult to construct the horn the would satisfy the dispersion for such large frequency range (say from about 1kHz to 20kHz), without introducing some kind of diffraction slots. So, it would be very interesting to see some 'independent' listening tests of JBL new horn (M2 monitor) connected to the D2 drivers. I will not be surprised, if over 12kH, that the dispersion of M2 would not be over 30 degs

    Best Regards
    Ivica.
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  4. #34
    Senior Member Lee in Montreal's Avatar
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    Quote Originally Posted by badman View Post
    Very cool looking setup- I always liked your "projecting" 2235H cabs.
    The cabs were initially designed for a 12" Kef B300 at 80 litres capacity (2.8cft). Then I adapted the cab for a JBL 15" driver. I needed more area to fit the driver, as well as more volume. The extension allowed both. I initially tried the (now) 95 litre cabinet (3,4cft) with a 2235h. Sadly, the 2235 needed more volume. At least 50% more to feel at ease. Then I went with 2225s and it was better but the ideal volume of 75l was exceeded and the woofer felt too soft, not enough lively, not to mention it is not a bass reflex driver. Not there yet. I did some testing with a driver that I thought I hated : the 2226. But thinking about it, it was specifically designed for a small bass reflex enclosure with its higher Qts and lower Vas. Doing some modeling and using the Vab = 5.7 * Vas * Qts^2 = 94litre formula, I realized the match was perfect. I tuned the reflex port to 47Hz and am now quite delighted. Bass goes deep enough, yet it is tight on top. I slightly tamed the midrange though. The simple two-way system sounds very good and works on all kind of musics. I will add a 12cft 2245 sub and shall be done with it. Is the 2226 perfect? Not. It needs some processing, but it can take a lot of it.

    That "forward cabin" design is something I may have seen in Europe in the mid 1970s. I always digged having that modular extension. I don't remember the brand though

    BTW That little bugger of a cab was built with 1" presswood and lot of bracing. It weights a ton. Probably around 200lbs.


  5. #35
    Senior Member Lee in Montreal's Avatar
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    I bolted the aluminum stands to a piece of half inch thick Russian Birch plywood for extra stability, and that's probably how it is going to stay for a couple of years.




  6. #36
    Senior Member Lee in Montreal's Avatar
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    Can anyone help me calculate a proper capacitor to equals the 6db/octave compensation at 3.5Khz on a 16 Ohm driver? ;-)

  7. #37
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    wrong question

    Quote Originally Posted by Lee in Montreal View Post
    Can anyone help me calculate a proper capacitor to equals the 6db/octave compensation at 3.5Khz on a 16 Ohm driver? ;-)
    It requires more than just a capacitor. See the 4430, 4435 for example. It requires a resistive network and a capacitor which bypasses that network. The bypass may also e a series resonance circuit.

    The easiest way to do that is with a digital xover.

    Ruediger

  8. #38
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    Quote Originally Posted by Lee in Montreal View Post
    Can anyone help me calculate a proper capacitor to equals the 6db/octave compensation at 3.5Khz on a 16 Ohm driver? ;-)

    2.839 micro farad capacitor. Erse has a calculator on there website. Its a nice one. Has them all.

  9. #39
    Senior Member Lee in Montreal's Avatar
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  10. #40
    Senior Member ivica's Avatar
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    Quote Originally Posted by Lee in Montreal View Post
    Can anyone help me calculate a proper capacitor to equals the 6db/octave compensation at 3.5Khz on a 16 Ohm driver? ;-)
    Hi Lee,

    Generally speaking C= 1/(6.2832*Fo*Zo),
    so Fo=3500 Hz, Zd=16 ohm , attenuation of -6dB (Ro=16) ==> Zo = Zd*Ro/(Zd+Ro)= 256/32= 8 ohm ==> C= 5.7 uF,
    but for different attenuation, different value of C would be get.

    but such theoretical value has to be get AFTER the measurements,
    in order to find out the real driver-horn response, and the sensitivity of the mid-bass (bass) driver in order to calculate the attenuation, and the influence of the 'high-pass" filter section.

    Regards
    Ivica

  11. #41
    Senior Member Lee in Montreal's Avatar
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    Hi Ivica. Thanks for the tech info. I am currently using an active crossover and two amps. Therefore levels can be infinitely altered. I know I can boost the frequency with the active crossover in order to get the CD correction (and that's what I am doing now) but using a passive way to attenuate the signal and replicate the CD curve is just a technical challenge. Also, so far I am quite happy with this simple two-way system. The next step is either to add a 2245 sub, or replace the two 2226 by a pair of 2245. I would loose midbass punch but would gain bottom end grunt. The result would probably be a more natural bass that I dont have to boost around 40Hz (where the 2226 dies).

  12. #42
    Senior Member ivica's Avatar
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    Quote Originally Posted by Lee in Montreal View Post
    Hi Ivica. Thanks for the tech info. I am currently using an active crossover and two amps. Therefore levels can be infinitely altered. I know I can boost the frequency with the active crossover in order to get the CD correction (and that's what I am doing now) but using a passive way to attenuate the signal and replicate the CD curve is just a technical challenge. Also, so far I am quite happy with this simple two-way system. The next step is either to add a 2245 sub, or replace the two 2226 by a pair of 2245. I would loose midbass punch but would gain bottom end grunt. The result would probably be a more natural bass that I dont have to boost around 40Hz (where the 2226 dies).
    Hi Lee,

    May be You can start with something like this

    Regards
    Ivica
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  13. #43
    Senior Member ivica's Avatar
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    Quote Originally Posted by Lee in Montreal View Post
    Hi Ivica. Thanks for the tech info. I am currently using an active crossover and two amps. Therefore levels can be infinitely altered. I know I can boost the frequency with the active crossover in order to get the CD correction (and that's what I am doing now) but using a passive way to attenuate the signal and replicate the CD curve is just a technical challenge. Also, so far I am quite happy with this simple two-way system. The next step is either to add a 2245 sub, or replace the two 2226 by a pair of 2245. I would loose midbass punch but would gain bottom end grunt. The result would probably be a more natural bass that I dont have to boost around 40Hz (where the 2226 dies).
    Hi Lee,

    Any trial ???

    Regards
    Ivica

  14. #44
    Senior Member Lee in Montreal's Avatar
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    I didn't try it because i should get about 15db boost at 20Khz from 3,5Khz. The graph you showed in the previous post isn't there.

  15. #45
    Senior Member ivica's Avatar
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    Quote Originally Posted by Lee in Montreal View Post
    I didn't try it because i should get about 15db boost at 20Khz from 3,5Khz. The graph you showed in the previous post isn't there.
    Hi Lee,

    Sorry, I have not been clear enough, so may be attached figure would explain:
    with the suggested network I have taken that the 'Driver-Horn' response would start to decline from 3.5kHz ( -6dD/Octave), so under 'usual' expectation that Your driver can be 'modeled' as 12 ohm load suggested network would 'compensate' about 16dB at 20khz, relative to the 1kHz driver output).
    So on my previous post expectable driver-horn response was presented.
    Here with red line network with 12-ohm load response is presented.

    Regards
    Ivica
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