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Thread: Beryllium Diaphragm in JBL 4355 speakers ?

  1. #16
    Senior Member ivica's Avatar
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    Quote Originally Posted by Dr.db View Post
    Thanks all for your replies, very appreciated!

    Would there have to be any changes to the 3155 crossover when using the Truextent dia´s in your opinion ?
    Hi Dr.db,

    As Be (Truextent) is said that it has several +dB in the mid-range region (as shown in the paper) over JBL Ti and Ti-SL, I would expect that some additional tweaking of the original 3155 network would be well-come.

    Regards
    ivica
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  2. #17
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    Quote Originally Posted by Dr.db View Post
    Would there have to be any changes to the 3155 crossover when using the Truextent dia´s in your opinion ?
    G.T. would very probably say yes, he never seemed to be a proponent of swapping transducers and networks willy nilly.

    I have come to the conclusion that, like all this stuff, it will be just fine for some folks and not so fine for other folks.

  3. #18
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    Quote Originally Posted by 4313B View Post
    There is nothing to be a fan about. As both Ed Meitner and Greg Timbers have maintained, it is a valid topology. I am aware of the fact that there are numerous people against the practice but nobody that matters cares. We are talking about guys that use a notch above state of the art gear that costs tens of thousands of dollars.

    It is like the Be diaphragms, simply put, most folks systems and hearing won't be able to take advantage of the increased performance. The truth is that the Be diaphragms are a SIGNIFICANT improvement over any other material, including Mg. If a person can't hear the difference then YEE HAW! They just saved a bunch of money arguably better spent on beer.
    4313B? Do we speak about the same language? I heard the diffrence! Coupled and mine! Guess what??

  4. #19
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    Quote Originally Posted by Challenger604 View Post
    4313B? Do we speak about the same language? I heard the diffrence! Coupled and mine! Guess what??
    There is no need for me to guess, the charge-coupled networks are better. If you think otherwise then you are wrong. Period. There is no "opinion" involved in this and I won't play that little game of being polite about it. To be blunt, there is no way in hell on earth JBL is going to waste one cent on biasing networks in their top of the line systems if there isn't an advantage in doing so. I will, however, concede that it is entirely possible that the 4355 simply doesn't have decent enough components to take advantage of charge-coupled networks. If that is the case then that would put their component complement a few steps below the components found in the 4406, the smallest system I have biased.

  5. #20
    Senior Member Odd's Avatar
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    Yes it is quite clear that charge-coupled networks sounds better.
    43XX (2235-2123-2450-2405-CC 3155)5235-4412-4406-4401-L250-18Ti-L40-S109 Aquarius lV-C38 (030) 305P MkII

  6. #21
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    Quote Originally Posted by Odd View Post
    Yes it is quite clear that charge-coupled networks sounds better.
    Hi Odd,
    I respectfully desagree.

    Happy New Year to you.
    C

  7. #22
    Senior Member Odd's Avatar
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    Quote Originally Posted by Challenger604 View Post
    Hi Odd,
    I respectfully desagree.

    Happy New Year to you.
    C

    Happy New Year!

    You have to build new crossover this year.
    Then we would agree.
    43XX (2235-2123-2450-2405-CC 3155)5235-4412-4406-4401-L250-18Ti-L40-S109 Aquarius lV-C38 (030) 305P MkII

  8. #23
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    Quote Originally Posted by Odd View Post
    Happy New Year!

    You have to build new crossover this year.
    Then we would agree.

    Thanks Odd!
    Oh no! My 4355's sound so good I won't change for nothing!
    Coupled crossover is like global warming! A huge scam!!
    Sorry! This is my own opinion with few...
    C

  9. #24
    Member sebackman's Avatar
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    Polarity

    I'm lazy when swapping diaphragms. I check polarity by applying 1,5v from a AAA battery to the diaphragm when mounted in the driver and the acoustical negative pole is the pole where applying + from the battery moves the diaphragm out from the phase plug. I prefer to apply voltage so it moves the diaphragm out from the phase plug but if you get it the other way around it inflicts no harm with such low voltage. I have never had a diaphragm touching the phase plug by doing this simple test.

    If the terminals are different between different driver motors, just turn the diaphragm180 degrees to get the terminal cables right.

    It does not move much but it is clearly visible to the eye with a good flash light.

    Don’t forget to sweep with a tone generator to be certain that there are no resonances after mounting. There should not be any rattle with these drivers but I find that sometimes there is anyway…

    I agree with what is said above regarding Be contra other dome materials but would like to add that the Be rolls off earlier than an SL (coated) diaphragm which will demand more EQ to go “all the way”.

    The SL is easier (less EQ) to extend above 12k (if desired) and may prove a good alternative when going for a 2-way solution or when the 077 cuts in very high.

    JBL solved the Be roll off to some extent by introducing 045 tweeter in the K2 models and the newer 43xx’s.

    To my ears the SL sound more musical than Alu and Ti, albeit it may not do so in a system designed for Ti or Alu diaphrams from the outset as mentioned above. I would not know as I only run active DIY designs.

    The difference between SL and Be is clearly audible but I would prefer a 2-way SL system before a more complex Be 3-way if I started from scratch. I’m right now building both alternatives with M2 waveguides and the reason is that I had all the components. If I had nothing to start with I would go 2430k as 4313b points out above, albeit the 4”drivers looks like they sound way much better J .

    And of course, my diaphragm discussion here is completely useless and irrelevant to all 4-way 43xx owners as they already do have a UHF/077/2405 unit built in. J

    Kind regards
    //RoB
    Last edited by sebackman; 01-15-2016 at 10:16 AM. Reason: correction
    The solution to the problem changes the problem.
    -And always remember that all of your equipment was made by the lowest bidder

  10. #25
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    Quote Originally Posted by Challenger604 View Post
    Coupled crossover is like global warming! A huge scam!!
    Another idiot on the waiting list for a brain donor...

  11. #26
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    CC is a means to an end. The most recent implementation is really neat with self powering the Dc bias from the signal.

    In many circuits a capacitor blocks Dc from entering the signal so the re e is nothing unique going on here.

    When the Ac voltage is not constant but is pulsed and frequency modulated the dielectric (foil) can rattle depending on how the capacitor is wound. The rattling results in non linear behavior of the dielectric. Applying the DC bias adds tension to the film/foil construction of the dielectric and minimize the rattling.

    Some capacitor are wound are made in such a way that the dielectric will not rattle (stacked foil) or has damping like Oil . This can be an expensive manufacturer process.

    With JBL it's alwsys been about the drivers so its nice to see the impact of the capacitor being removed from the equation.

    I am not sure if the Greens would like it with twice the values and quantity of parts.

  12. #27
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    Back OT if you can find diamond aluminum diaphragms l am sure you will be quite happy. Also consider a Westlake or Smith horn atop the 4355. Going Be is an expensive exercise and unless with rest of the food chain is pristine you may hear more about the rest of your system than what is on the record.

    Beyond that its real tweeker journey. Most don't really see the impact of a series inductor. Inductors are the evil curse of passive crossovers.

    If you made the 12 inch midcone fully active with the correct voltage drive the performance would elevate to a new level . Get the midrange right and you stop worrying about everything else. I am thinking about getting another B4 First Watt active crossover and going 3 way active with my 4345s.

  13. #28
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    Quote Originally Posted by 4313B View Post
    Another idiot on the waiting list for a brain donor...
    Why the direct insult?
    Incapable to argue?

    Prove to me that it's better? Did you hear two pairs of 4355's with differents xover same amps? Did you EVER heard just one pair? Have you seen a pair?? So until you do! Keep your insults in your mouth!

  14. #29
    Senior Member pos's Avatar
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    Well, Challenger604, calling other people's work a scam *is* an insult
    (and beside that, considering that global warming is a scam is... kind of stupid)

  15. #30
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by Challenger604 View Post
    Did you EVER hear just one pair? Have you seen a pair??
    Now children . . . we're all friends here, right?

    Not defending the tone but I believe 4313b created the circuitry design for the CC network I'm using in my 4345, and I'm quite certain he's heard more 43xx versions than many if not all of us here. And built quite a few, too.

    I guess the same question you asked could be asked of you, since you made the first of the damning declarations.
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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