Page 6 of 7 FirstFirst ... 4567 LastLast
Results 76 to 90 of 100

Thread: 2450 Dia

  1. #76
    Senior Member
    Join Date
    Apr 2003
    Location
    GTA, Ont.
    Posts
    4,995
    Quote Originally Posted by speakerdave
    Is that because of all the mattresses, old tires and catcher's mitts they hafta put in the 16 ohmers to slow down the electrons?
    - Good One Dave !

    - But no , I'd say it's a matter of making a comparison between the BL figures when looking at the so called 8 ohm versions vs the nominal 16 ohm types . Just about always, the 8 ohm diaphragms have more electromotive force after a per unit normalization . It stands to reason that these higher BL types will also have more modal breakup issues and thus measure slightly different .

    - In the SR world up here in central Canada , it's long been a held opinion among a certain older crowd ( defined as over 55 yr , as of 2006 ) that JBLs' 16 ohm type diaphragms sounded "smoother" / across the board for the different models ( FWIW ) . Why ? Think of the BL differences that Giskard ( & others ) like to chew on when someone creates a hybrid ( franken -) woofer using 2235H cone kits in an overmagged core assembly.
    - That same focus can be shifted onto diaphragms when they are put into none standard motors ( especially when the motor has a different gauss level , ie giving a non-standard BL coefficient ) .
    - A lot of these issues can be explained as what's the best performing balance of FR vs "sound" ( made between a diaphragms mass and the BL that indicates the strength of the motive forces ).


  2. #77
    RIP 2011 Zilch's Avatar
    Join Date
    Jun 2004
    Location
    Berkeley, CA
    Posts
    10,036
    Quote Originally Posted by stevem
    Check this out:

    http://www.jblproservice.com/pdf/Dis...els/2452HJ.pdf

    The SL version probably has an Aquaplas coating.
    And a smaller 3.25" mounting bolt circle like the 2450SL to mate with PT waveguides?

    A throatless "Optimized Aperture" driver, looks like....

  3. #78
    Senior Member stevem's Avatar
    Join Date
    Mar 2004
    Location
    New Jersey, USA
    Posts
    280
    Quote Originally Posted by Zilch
    And a smaller 3.25" mounting bolt circle like the 2450SL to mate with PT waveguides?

    A throatless "Optimized Aperture" driver, looks like....
    According to the spec sheet, the 2452H has a 4 1/2" bolt circle like the 2451. Does this mean it won't work with the PT waveguides? You think the SL version has the smaller bolt circle?

  4. #79
    RIP 2011 Zilch's Avatar
    Join Date
    Jun 2004
    Location
    Berkeley, CA
    Posts
    10,036
    Yup.

    http://www.jblproservice.com/pdf/Dis...els/2450SL.pdf

    I'm not real good at guessin' this stuff, tho....

  5. #80
    RIP 2011 Zilch's Avatar
    Join Date
    Jun 2004
    Location
    Berkeley, CA
    Posts
    10,036

    For Giskard,

    The "List" as I see it

    Engineering design specs for:

    2450
    2450SL
    2451
    2451SL
    2452
    2452SL

    Also, what is 2450SL-A diraphragm. Ribbed, with Aquaplas?

    D16R2450SL is not on the price list. Is D16R2451SL the same?

    Is the 475 diaphragm the same as either of the available Pro "SL" diaphragms?

  6. #81
    Senior Member stevem's Avatar
    Join Date
    Mar 2004
    Location
    New Jersey, USA
    Posts
    280
    Any info on these yet?

  7. #82
    RIP 2011 Zilch's Avatar
    Join Date
    Jun 2004
    Location
    Berkeley, CA
    Posts
    10,036
    From the pic he posted today, Giskard may still be at JBL, looks like....

  8. #83
    RIP 2011 Zilch's Avatar
    Join Date
    Jun 2004
    Location
    Berkeley, CA
    Posts
    10,036

    Air....

    Ah-HEM!!

    http://www.jblpro.com/installedsound/support/index.html

    2452H-SL, PT-F1010HF, NL200t3 biased and bypassed, L88 plugged.

    Red = HF only, windowed.

    Org = Full system, unwindowed.

    [Who's J.R.? :dont-know]
    Attached Images Attached Images   

  9. #84
    RIP 2011 Zilch's Avatar
    Join Date
    Jun 2004
    Location
    Berkeley, CA
    Posts
    10,036

    "Next Generation" - A different animal?

    Per request, impedance, phase, and response plots for 2 units 2452H-SL, on PT-H95HF waveguides. Frequency response is shown at both 10 and 5 dB/division. Raw FR plots unsmoothed, filtered ones 1/6 octave.

    I'm not seeing any breakup mode here, unless it's at 10 kHz; I doubt the waveguides are masking it.

    The two units are not perfectly matched. Don't know if I'm going to do anything about that, tho, at this point....

    Sorry 'bout the wide impedance/phase plots. I want to show max resolution for TimG's analysis.

    VP7215/95 frequency response, bottom. Same driver and horn, filter/EQ unknown.

    Looks like #2 (blue) is the "good" one from that; I doubt they EQ above 10 kHz.

    [Measure your drivers, folks, even (especially) the $1315 ones.... ]
    Attached Images Attached Images      

  10. #85
    TimG
    Guest

    2452 response

    That response graph is very impressive. That is the best response curve I have seen from any JBL compression driver yet. I don't see any break up in the response curve before about 19kHz. I found the price, at $1315 it is less expensive than the list price for the 2435HPL. Maybe some B-stock will turn up some day that I could afford. If you have 2 of those and 4 2235H's, you really need to throw them together with an Everest style crossover and let us know how they sound with your 2452 horns.

    Here is an example of a different large format compression driver with obvious breakup in both the frequency response and impedance sweep curves. This example is the B&C DE610. I would not try to use a driver like this above 10kHz.

    Here is the frequency response and the impedance curve. Notice the peaks in response and the corresponding peaks in the Imp curve where part of the diaphragm is no longer behaving like a piston.
    Attached Images Attached Images   

  11. #86
    RIP 2011 Zilch's Avatar
    Join Date
    Jun 2004
    Location
    Berkeley, CA
    Posts
    10,036
    One 2235H will have to do until Mr. Widget makes me a

    V--E--R--Y- -W--I--D--E

    horn....

    [Not bad on PT Waveguides, actually, and the compensation is, well, uhmm, "straightforward...." ]

  12. #87
    RIP 2011 Zilch's Avatar
    Join Date
    Jun 2004
    Location
    Berkeley, CA
    Posts
    10,036

    2452H-SL on JBL 2352 Horn

    Horn flange is drilled to accept this bolt pattern, same as 243x drivers.

    1) Impedance and phase.

    2) Frequency Response of driver alone, with compensation, and full range with 2235H in 4507, two ports closed.

    3) Comparison with 2435HPL. 2452H-SL requires 10 dB less "push" at 20 kHz; no more than at 10 kHz, apparently.

    4) Published FR of 2451 on 2352. "-SL" version upublished, and I don't have one.
    Attached Images Attached Images     

  13. #88
    RIP 2011 Zilch's Avatar
    Join Date
    Jun 2004
    Location
    Berkeley, CA
    Posts
    10,036
    O.K., so how do they sound?

    What JBL says: "Crystal-clear."

    Also, what Earl suggests: "Splashy - fresh, exciting, open-sounding."

    Who's gotta pair 2451SLs they can send me to test for comparison?

    [How much for a pair of 476Be? ]

  14. #89
    Obsolete
    Join Date
    Apr 2003
    Location
    NLA
    Posts
    14,548
    Now I see where all the recent posts came from.....
    Quote Originally Posted by Zilch View Post
    The two units are not perfectly matched. Don't know if I'm going to do anything about that, tho, at this point....
    They are fine for their intended application.
    Quote Originally Posted by TimG View Post
    I found the price, at $1315 it is less expensive than the list price for the 2435HPL.
    Buy them! JBL would love to sell a ton of them!
    I would love to see people here buy a ton of them.
    I wonder why they are less expensive than a 2435.
    Who cares! Just buy them.
    Quote Originally Posted by TimG View Post
    If you have 2 of those and 4 2235H's, you really need to throw them together with an Everest style crossover and let us know how they sound with your 2452 horns.
    I'd use the dual 1501AL's, 476Be and the Everest II horn myself.
    Quote Originally Posted by Zilch View Post
    How much for a pair of 476Be?
    $7,000 at present but that could go up.
    If current practice continues the diaphragms won't be generally available (to put into legacy 4" cores) since JBL does "driver replacement" on these high ticket items. You blow a driver, you get a new one (often within 48 hours).

  15. #90
    RIP 2011 Zilch's Avatar
    Join Date
    Jun 2004
    Location
    Berkeley, CA
    Posts
    10,036
    Quote Originally Posted by Giskard View Post
    $7,000 at present but that could go up.
    If current practice continues the diaphragms won't be generally available (to put into legacy 4" cores) since JBL does "driver replacement" on these high ticket items. You blow a driver, you get a new one (often within 48 hours).
    OUCH!

    That puts them into an especially rarified zone for DIY, I'd say....

    Quote Originally Posted by Giskard View Post
    Now I see where all the recent posts came from.....
    Yeah, not just slappin' stuff together randomly anymore....

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Network for 2450 and 2405
    By Harryup in forum Lansing Product Technical Help
    Replies: 1
    Last Post: 12-23-2004, 06:53 AM
  2. 2450 SL diaphram
    By Maron Horonzakz in forum Lansing Product Technical Help
    Replies: 2
    Last Post: 11-04-2003, 09:58 AM
  3. 22235a, 2226j, 2360, 2450, 077
    By Dieter in forum Lansing Product General Information
    Replies: 11
    Last Post: 09-06-2003, 03:15 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •