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Thread: time delay problem JBL 4343 (3143 network)

  1. #1
    Senior Member B&KMan's Avatar
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    time delay problem JBL 4343 (3143 network)

    Time delay problem JBL 4343 (3143 network)

    Hello fantastik group !!

    (sorry for my poor english)

    Recently, I run test calibration with my analyser for check spectrum response on driver.

    Big surprise result the time delay integration is little false on cross-over 3143.
    The time delay is 0,671 MS more faster for the 2405 for th rest of the drivers.

    Well this effect is not change pretty well the sprectrum response but ruin the phase match...

    Do you have any information for modification, repair or upgrade cross over for fix this effect ??

    (I attache too small pict where the phenomenon is produce.)
    thanks
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    Senior Seņor boputnam's Avatar
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    Re: time delay problem JBL 4343 (3143 network)

    Originally posted by B&KMan
    Do you have any information for modification, repair or upgrade cross over for fix this effect ??
    Well, I ain't no expert in this, but one solution would be to take the 3143 out of the signal path, and go with an external four-way active crossover and time-delay the four signal components until you get the result you need.

    Or, just have another glass of fine red wine, and sit back and enjoy the pleasures of vintage JBL engineering!
    bo

    "Indeed, not!!"

  3. #3
    Senior Member B&KMan's Avatar
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    I hope found the trick for sending better pict in regards with the limitation forum.
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    Senior Member B&KMan's Avatar
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    Re: Re: time delay problem JBL 4343 (3143 network)

    Originally posted by boputnam
    Or, just have another glass of fine red wine, and sit back and enjoy the pleasures of vintage JBL engineering!
    Yes this second option is particulary work : the acohol have a hight fading effect in high frecuency perception...

    and again...


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    Senior Member GordonW's Avatar
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    I'm just wanting to be clear here- so, the bigger of those two spikes on the time response curve, is ALL THREE of the other drivers in the 4343 stacked up on top of each other, ie, the midrange horn, the midbass and the woofer? If so, that's pretty remarkable... that would very consistent response from drivers of different mechanical acoustic centers.

    My suggestion, might be to seperate JUST the 2405 from the other three drivers- run a tri-amp setup- with the 2231/2235 woofer on one amp, the 10" midbass and mid horn on one amp, and the 2405 on a third amp. Then, use a digital time delay, to delay the 2405 .67ms. That shouldn't be too terribly hard- all you'd have to do, is seperate the 2405's crossover section from the rest, and just run another amp from a time delay unit for just that tweeter and crossover...

  6. #6
    Senior Member B&KMan's Avatar
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    Originally posted by GordonW
    I'm just wanting to be clear here- so, the bigger of those two spikes on the time response curve, is ALL THREE of the other drivers in the 4343 stacked up on top of each other, ie, the midrange horn, the midbass and the woofer? If so, that's pretty remarkable... that would very consistent response from drivers of different mechanical acoustic centers.

    YUP, the rest of the driver is very consistent time delay integration. But other hand the lower frequency is low = long in time so, the impulse test response on lower frequency is too long for test as the same rate speed.

    But my many test with corrolaire speed vs frequency is expose excellent integration for the rest of driver... Superbe job.

    but if the engeener is macht delay of the HF why is not ability to match UHF ??? the rest of picture is too clean for I accept this delay...
    ---
    If I calculate the distance to backward UHF driver for delay alignment: it is +- equal to position of the HF diaphram position (back 22 cm) (sic)

    Unfortunately I'm not very good in electronic theorie and I have difficult to understand if my cross-over (3143) is busted in one component or is a error design... or mismatch connection inside cross-over...

    but this problem is same at two monitor in exact same time delay result.

    this time delay it is consider small or realy problematic ???

  7. #7
    Senior Member Ian Mackenzie's Avatar
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    JBL has previously published a grou delay for this and other monitors. They claimed its group delay falls within the accepted limits of human perception (ref Sound Engineering John Eargle)

    Ian

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    Senior Member B&KMan's Avatar
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    Originally posted by Ian Mackenzie
    JBL has previously published a grou delay for this and other monitors. They claimed its group delay falls within the accepted limits of human perception (ref Sound Engineering John Eargle)

    Ian

    WOW !!! you have a big and precious conncection

    It is possible to give the link or exact reference of paper or copie paper

    please please please

    I'M shure anybody is real interestd by this paper issue.

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    Senior Member Guido's Avatar
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    Re: Re: time delay problem JBL 4343 (3143 network)

    Originally posted by boputnam
    Or, just have another glass of fine red wine, and sit back and enjoy the pleasures of vintage JBL engineering!
    Bo,

  10. #10
    Senior Member Ian Mackenzie's Avatar
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    Originally posted by B&KMan
    WOW !!! you have a big and precious conncection

    It is possible to give the link or exact reference of paper or copie paper

    please please please

    I'M shure anybody is real interestd by this paper issue.
    Are you kidding.

    Go buy the book on Amazon, millions of copies sold

    ISBN: 0442222211

    My copy is currently on loan to Kent English Passlabs

    Ian

  11. #11
    Senior Seņor boputnam's Avatar
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    Originally posted by Ian Mackenzie
    (ref Sound Engineering John Eargle)
    Sound Recording by John Eargle - on Amazon:

    http://www.amazon.com/exec/obidos/tg...glance&s=books

    My copy is way too valuable to loan-out to any hi-falootin' audio wizard in the mystical Sierra...
    bo

    "Indeed, not!!"

  12. #12
    Senior Member Ian Mackenzie's Avatar
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    My copy is way too valuable to loan-out to any hi-falootin' audio wizard in the mystical Sierra...

    I find sharing knowledge the most valuable aspect of this interest.

    Those who don't stand dormant.

    The question is Bo do you understand and have learnt from the John Eargle text or does it sit gathering dust in the bookcase.

    "For those unaware Kent is a physicist formerly of the nuclear energy commission and one of the nicer people I met in my travels and the least I could offer for his hosting & friendship was a permanent loaner of my in-flight reading. Besides I plan to order the current edition soon enough."


    Ian

  13. #13
    Senior Member B&KMan's Avatar
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    thanks for your references, I attemp to buy soon...

    for my side the B & K info relativ of standart question for average impulse mesure and typical response of ear is expose other face ...

    Show pict...

    In third face of problem the problem of builder amp is build a more fast possible response in circuitry and speaker is normally the reflect of the same problem, impulse and transient information is very very fast...

    the ear is catch the difference....
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  14. #14
    Senior Seņor boputnam's Avatar
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    Originally posted by Ian Mackenzie
    The question is Bo do you understand and have learnt from the John Eargle text or does it sit gathering dust in the bookcase.
    Actually no, friend - it's stuffed into my gig bags along with that excellent "Live Sound Mixing" by Australian Duncan Fry (from ARX) you gifted me on your visit! When the band (and you, too...! ) wander off chasing the babes, I try and get in a little reading...
    bo

    "Indeed, not!!"

  15. #15
    Senior Member Ian Mackenzie's Avatar
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    Bo,

    Well with so many talented people around you they can afford to wonder and enjoy darlings of pleasure and soil the drapes...all work and no play makes a dull boy after all.

    Any way your married to a sweetie, keep your nose in the book and behave yourself.

    B&K,

    About the whole group delay thing, its got more ins and out than a duck's arse to measure and make an sense of, then there's the subjective debate among researchers. A number of notable and damn fine brands like Duntech has exploited this I think for marketing reasons but there are equally as many other alternatives.

    I suppose it would be nice to have a perfect point source but as was explained by guru's in another thread, this can only exist for one sweet spot in time and space.

    With the 43xx 4 ways the advantages far outway the minuses and I think the focus was on flat amplitude response on axis rather than absolute phase at the time, flatness of response certainly more audible than phase shift.

    Ian

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