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Thread: Which horns for JBL 2451 Be drivers?

  1. #16
    Senior Member ivica's Avatar
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    Quote Originally Posted by Ian Mackenzie View Post
    My comments is the limit (width) of the diffraction slot in the horn is possibly the issue . I

    This can result in a pencil beam at frequency = or higher width of the slot
    Btw l must re measure my Tad 4003s

    If l lost sleep on it l might by a Scan BE tweeter and cross it over actively with a small Pass Aleph amp @20000 hz
    Hi Ian,

    I will agree with You that is why on PT-H95HF and M2 horns such slot size is only 3/4-inch width somewhere in the throat part of the horn.
    I think that using JBL D2430K, or BMS4592 would have a great problem to find proper horn that would be good for all applied frequencies
    from the bottom to the top. May be 476Be would be "in" the same problem.

    regards
    ivica

  2. #17
    Member Mitchco's Avatar
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    Quote Originally Posted by johanwholst View Post
    Thanks for the inspiration for a lower xo with 2384
    Dropped from 750 to 650 last night, and as you mentioned; it blends better with the midbasses even some additional distortion may be introduced
    Cool, I really like this waveguide. For fun, here are the frequency and phase response and distortion measurements. This was with the mic 1 meter away on axis, in-room, no XO, 83 dB SPL ref and sweep from 600Hz on up:

    Name:  JBL 2453h-SL on 2384 waveguide 1m fr and phase.jpg
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    Personally, I don't think any UHF driver is needed, and depending on one's age, such as myself, likely never to hear it :-) The distortion is quite low, even at 600 Hz. I certainly could mate the driver better to the waveguide as evidenced by the notch at 12.7 kHz. However, I use DSP eq for constant directivity waveguide eq and it smooths it out nicely, with response to -3 dB at 19 kHz relative to a house curve target response. User notnyt got similar measurements to mine: http://www.avsforum.com/forum/89-spe...l#post42209001

    Here is notnyt's measures of the 2452h-BeX4008 combo on the 2384: http://www.avsforum.com/forum/89-spe...l#post41972249

    And JBL 2435HPL: http://www.avsforum.com/forum/89-spe...l#post42272969

  3. #18
    Senior Member ivica's Avatar
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    2453 & 2384 STRANGE Respone

    Quote Originally Posted by Mitchco View Post
    Cool, I really like this waveguide. For fun, here are the frequency and phase response and distortion measurements. This was with the mic 1 meter away on axis, in-room, no XO, 83 dB SPL ref and sweep from 600Hz on up:

    Name:  JBL 2453h-SL on 2384 waveguide 1m fr and phase.jpg
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Size:  58.7 KBName:  JBL 2453h-SL on 2384 waveguide 1m distortion.jpg
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Size:  56.9 KB

    Personally, I don't think any UHF driver is needed, and depending on one's age, such as myself, likely never to hear it :-) The distortion is quite low, even at 600 Hz. I certainly could mate the driver better to the waveguide as evidenced by the notch at 12.7 kHz. However, I use DSP eq for constant directivity waveguide eq and it smooths it out nicely, with response to -3 dB at 19 kHz relative to a house curve target response. User notnyt got similar measurements to mine: http://www.avsforum.com/forum/89-spe...l#post42209001

    Here is notnyt's measures of the 2452h-BeX4008 combo on the 2384: http://www.avsforum.com/forum/89-spe...l#post41972249

    And JBL 2435HPL: http://www.avsforum.com/forum/89-spe...l#post42272969

    Hi Mitchco

    I think the response round 10kHz is not good. May be some kind of strong reflection has happened.
    Did You try the same driver with different horn?
    I have seen such behaviors with 2441 drivers and some horns too, but with much narrower notch at 10kHz.

    regards
    ivica

  4. #19
    Member Mitchco's Avatar
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    Quote Originally Posted by ivica View Post
    Hi Mitchco

    I think the response round 10kHz is not good. May be some kind of strong reflection has happened.
    Did You try the same driver with different horn?
    I have seen such behaviors with 2441 drivers and some horns too, but with much narrower notch at 10kHz.

    regards
    ivica
    Hi ivica, yes, that measure was without a proper spacer between the driver and waveguide. With a 1/2" spacer:

    Name:  JBL 2453H-SL on 2384.png
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    As mentioned, could be made better with sanding the waveguide's ridges where the CD mates to the waveguide. As johanwholst indicated, the build quality is not the greatest. But without sanding down, the eq'd response at the LP for the 2 way turned out ok:

    Name:  Audiolense biamp fr.jpg
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    Kind regards, Mitch

  5. #20
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    2451 & 2384

    So far am leaning towards 2451be+2384 or Radial type horn.

    Will I need a spacer between 2451 & 2384 horn combo?
    What is the horn model no from JBL 4367? Is it the
    H9800?

    Herman

  6. #21
    Senior Member Ian Mackenzie's Avatar
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    Guys how big is the 2384? Not sure about the Waf?

    I assume a Tad 4003 would work

  7. #22
    Member Mitchco's Avatar
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    AVSforum user notnyt shared this with me on his 2384 waveguide:

    Name:  8NJtWiJ.png
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    Dimensions of the waveguide can be found in the JBL 4722 product sheet: https://www.jblpro.com/ProductAttach...S4722_0509.pdf Btw, the product photo is crap, the woofers are black.
    It's 30" wide x 15" high x 15" deep, which includes the compression driver. More like 26" x 12" for the waveguide area that smoothly transitions to the flat front.

    WAF - well, it depends, it is pretty big waveguide for sure. I count my lucky stars that my wife, who first noted when the 4722's showed up that they were bigger than her washer and dryer - lol! However, she loves the big sound. I sometimes review and measure speakers for computeraudiophile.com and they are all smaller and more expensive. My wife says the bass sound from those smaller speakers sounds like it is coming from a "milk carton". I made mention that I may get something smaller and she said absolutely not... haha - a dream come true! I can share a pic of them in a living room environment for waf, but I don't want to step on Hermans thread.

  8. #23
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    spacer

    Can you please provide more information on the needed spacer? I will use 2451 CD with 2384 waveguide.

    thank you,
    Herman

  9. #24
    Member Mitchco's Avatar
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  10. #25
    Member sebackman's Avatar
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    Dear Herman,

    I concur with most points above.

    Given a choice, get 16ohm dias.

    If you do go Be you will want a UHF as also iterated by ivica, Baldrik and others. The Truextents falls off rather sharply above 12k. DSP EQ can compensate but does not sound as good as 3-way to my ears. I use a BSS BLU800 for DSP so I dont think that is the limiting factor. I always ended up with JBL 045s in my Be setups. JBL also always used UHFs for all their Be K2s.

    I have built both 2-way and 3-way systems with these components and the best sounding system was using 2451 core with 475Nd dias on the M2 wave guide. The SL diaphragms can go all the way up and requires much less EQ. You will sacrifice some of the Be sound but there are so small differences and considering how much easier it is to get a 2-way to work compared with a 3-way it is an easy choice as johanwholst is pointing out. And they are much cheaper also. Knowing back then what I know today I would not have bought Be dias for M2 WG usage.

    A note to Mitchcos post, I do concur, but you seem to use SL dias which is fine. The curve would be different with 4 Be dias. Even if most of us cannot hear 15k let alone 20k the overall sound is much more pleasing with a speaker that does produce sound all the way up. At least to me. I can mute my 045s and tune the 2451Bes to give a reasonable curve but is does not sound the same. However, with the 2451/475Nd combo on M2s there was no need at all for additional UHF.

    I also do have access to a pair of D2s and my personal choice is still the 4 drivers sound wise for DYI. But I respect that others may have an opposite view.

    Maybe worth mentioning is that the M2/K2s are systems that few of us can get close to even using top notch components unless we clone a JBL factory system of our liking. To get to 95% with DIY is achievable but to get to 100% without the resources and time put in by manufacturers like JBL is considerably much more difficult, even with knowledge and good measuring tools.

    I have a few of the older horns and to my ears (and mic) they differ substantially from M2 (and probably 4367). Only your ears can decide. Mine like the M2s. -And the small cheap plasticWG from the VTX F12/F15.

    I have not been able to access the 4367 horns as a spare part but there is no reason to expect that they should not sound great. The 4365 horns do not have the same sound to my ears. Not worse or better, but different. You will have to judge by listening.

    I would absolutely audition M2 and/or 4367 (WGs DIY or JBL speakers) before settling on 2384. Or any other wg for that matter.

    I can send measuring data on 2451 Ti, SL and Be on M2 if you want.

    Kindregards
    //Rob
    The solution to the problem changes the problem.
    -And always remember that all of your equipment was made by the lowest bidder

  11. #26
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    Dear Rob
    Great post, and i agree. Partially
    A 4" driver with Be mounted to a modern CD does benefit from a tweeter with the following reservations:
    -The tweeter is up for the job (forget about the old JBL tweeters and other ring radiators)
    -The horn in front of the tweeter matches the horn in question
    -A decent DSP solution us used
    -The setup is measured with a prober calibrated mic and dialed to perfection.

    To get this right is costly and hard work. I know only of two tweeters that would use with the horns I prefer; 045be and tad 703. That means we are venturing into expensive territory for hopefully a slight improvement in sonics.
    If this quest is worth it is must be highly individual. For me it was, but to be honest, the improvement is marginal, and I have used the M2 waveguide and 2384 for quite som time without the tweeter, and frankly; I did not really miss it. But the classical audiophile paradox, when it is there, I would not drop it.

    Another intresting thing to consider, is that instead of uprgrading from SL to Be, maybe invest in a pair of tweeters? A pair of 045bes does not cost much more than the TE diaphragms, and to my ears can be used as low as 10k.

  12. #27
    Member sebackman's Avatar
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    I totally agree with your points.

    With SL diaphragms in a 2451 core on the M2 WG's there is, in my view, no need for UHF at all. My measurements also confirm this. I have used 475Nd diaphragms but I think they are the same as D16R2451SL. There are at least no visible differences except the markings. I'm loading a good pair of 2451's with brand new D16R2451SL diaphragms as we speak and will measure them tonight. I can revert if I find any outrageous differences compared to the 2451/475Nd pair lying next to them.

    I have not had the same long experience with the 2384, so I leave any comments to you as I know you have done extensive listening to both.

    Regarding 045Be's there is actually a 045Ti-1 that sounds equally good to my ears and are easy to obtain (and cheaper) as a spare part. I think it will be very difficult to hear difference between Ti and Be above 10-12k.

    Regarding 045 XO I think JBL used passive 8k in Array 1400, so maybe it is the UHF horn setting the limits.

    Kind regards
    //Rob
    The solution to the problem changes the problem.
    -And always remember that all of your equipment was made by the lowest bidder

  13. #28
    Senior Member Ian Mackenzie's Avatar
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    Very informative

  14. #29
    Senior Member ivica's Avatar
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    Quote Originally Posted by sebackman View Post
    I totally agree with your points.

    With SL diaphragms in a 2451 core on the M2 WG's there is, in my view, no need for UHF at all. My measurements also confirm this. I have used 475Nd diaphragms but I think they are the same as D16R2451SL. There are at least no visible differences except the markings. I'm loading a good pair of 2451's with brand new D16R2451SL diaphragms as we speak and will measure them tonight. I can revert if I find any outrageous differences compared to the 2451/475Nd pair lying next to them.

    I have not had the same long experience with the 2384, so I leave any comments to you as I know you have done extensive listening to both.

    Regarding 045Be's there is actually a 045Ti-1 that sounds equally good to my ears and are easy to obtain (and cheaper) as a spare part. I think it will be very difficult to hear difference between Ti and Be above 10-12k.

    Regarding 045 XO I think JBL used passive 8k in Array 1400, so maybe it is the UHF horn setting the limits.

    Kind regards
    //Rob
    i

    Hi Bob,

    about 20dB EQ ....????

    regards
    ivica
    H

  15. #30
    Administrator Robh3606's Avatar
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    Don't forget the PTH1010 a poor mans M2. They work very well with the large format 1.5" drivers and are easy to EQ. Here are passive preliminary networks using a 476Mg. I use them with 2435's and they sound good and image very well. Also a much smaller alternative and very shallow depth wise so no significant delay issues at crossover.

    Rob
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