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Thread: KM2

  1. #121
    Senior Member Anti K's Avatar
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    Uhf 045

    Question:

    coming back to tweeter 045.
    Tech spec says the sensitivity is 87dB (!). Is it mistake or does the JBL OR tiny wavequide rise as high as 96dB: sensitivity of DD67000.
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  2. #122
    Senior Member pos's Avatar
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    There is a typo indeed: it should read 1V instead if 2.83V, as confirmed in the curve page 8 of the EDS: http://www.audioheritage.org/vbullet...1&d=1350657541

    There is a 9dB difference when going from 1V to 2.83V, so 87dB becomre 96dB...
    Also note that this is the 045Mg. The Be version might possibly be a bit more sensitive in that frequency range.

  3. #123
    Senior Member Anti K's Avatar
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    Quote Originally Posted by pos View Post
    There is a typo indeed: it should read 1V instead if 2.83V, as confirmed in the curve page 8 of the EDS: http://www.audioheritage.org/vbullet...1&d=1350657541

    There is a 9dB difference when going from 1V to 2.83V, so 87dB becomre 96dB...
    Also note that this is the 045Mg. The Be version might possibly be a bit more sensitive in that frequency range.
    THNX.

    Yep, noticed it's Mg.
    Be version Spec I'm not able to find anywhere.

  4. #124
    Member sebackman's Avatar
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    Hi Pos.

    No typo. They are very low sensi but also 4 ohms so in reality they are about 91db. And they do add some gain from the horns. I use K2 S9900 horns.

    At least that is what my measures shows on mine.

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

  5. #125
    Senior Member Anti K's Avatar
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    Quote Originally Posted by sebackman View Post
    They are very low sensi but also 4 ohms so in reality they are about 91db. And they do add some gain from the horns. I use K2 S9900 horns.

    //Rob
    That surprises me.
    At least these are compression drivers...

    That horn, visually same?
    https://reconingspeakers.com/product...rn-361861-002/

  6. #126
    Member sebackman's Avatar
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    They appear to have different part numbers.

    The K2 S9900 seem to use 365181-002 (93db system 045Be-1 XO 24db @ 15kHz) whereas the DD66000/DD67000 (96db system 045Be-1 XO 24db @ 20kHz) is stated as 361861-002.

    The UHF filters differ slightly between DD66000 and DD67000 even if the specs are the same. Odd.

    K2 S9800 uses 337106-002 (94db system 045Be XO 24db @ 10kHz)

    Slightly more UHF damping in S9800 than S9800 and lower XO suggest earlier sensitivity numbers are reasonable with beaming in the WG compensation for drop off in sensitivity.

    I have no idea what the difference might be in the WG's. I XO mine @ 12kHz.

    As you are building your own DIY system you can combine as you see fit. IMHO there are is limited lessons to learn from the "factory systems" when it comes to details, you just have to build, measure and listen. That is where the fun is.

    I also use SUB1500, as Widget, and in sealed boxes as subs as they were designed for. Works fine if you have lots of power to them. However, I would recommend ported designs with the drivers you have identified.

    I still say skip UHF and go for a pair of 476Mg if you can find them. Or settle for a nice pair of 2451SL, which listening wise comes to a very similar level . -Less complicated, fewer power amps and saves money & time.

    With high quality DSP power available at low costs there is really no need to go 4-way anymore, as the M2 has made very evident. And if the output of the 2216 is not enough use two, as many have suggested. Or put a 2269 sub below as you seem to like.

    Unless designed for cinema use with lots of LFE I would go dual 2216 before 2269.

    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

  7. #127
    Senior Member pos's Avatar
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    Quote Originally Posted by sebackman View Post
    Hi Pos.

    No typo. They are very low sensi but also 4 ohms so in reality they are about 91db. And they do add some gain from the horns. I use K2 S9900 horns.

    At least that is what my measures shows on mine.

    //Rob
    Hi Rob,

    There is a typo: the table shows 87dB/1m at 15kHz for 2.83V, whereas all the graphs show that same 87dB value at 15kHz for 1V.
    If the voltage value found in the curves is the right one (which is most probably the case), then this driver's sensitivity at 15kHz is:
    • 87dB for 1V
    • 93dB for 2V, which is 1W for the nominal 4 ohm load here
    • 96dB for 2.83V, which is the voltage value at which the DD67000 sensitivity is calculated (as well as pretty much all JBL loudspeakers using the 045)



    The curves also indicate that the measurement is taken with the S9800 UHF waveguide.
    I doubt the choice of waveguide makes any meaningful difference at 15kHz.

  8. #128
    Administrator Robh3606's Avatar
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    When I built my Be Arrays I used the 045Be and it was in the upper 90's as far as sensitivity. I had to pad it down to meet the LE-14H-3 so it is definitely not 87Db. That documents seems a bit messed up. If you look at the high level measurement it looks a bit closer to the 045Be measurements we have.

    Rob
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  9. #129
    Member sebackman's Avatar
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    It seems like XO and horn does play an important role in usage/sensitivity of the 045 family (Ti, Mg & Be).

    I agree that the spec says 2,83V and the graph (if level calibrated) seem to say 1V. Maybe you are right, I rest my case.

    Here are the system sensitivities for some of the 045 systems

    DD66000 & DD67000 are 96db XO20k, 0,47 ohms in series no other attenuation, 24 db
    S9900 are 93db XO 15kHz, 0,47 ohms in series no other attenuation, 24db
    S9800 are 94 db XO 10kHz, 1,5 ohms in series no other attenuation, 24db
    1400 Array are 89db XO 8kHz, 7,5 ohm in series no other attenuation, 24db

    The sensitivity drop with frequency and the higher the XO the less the attenuation. Makes me wonder how they manage to get the top end in the S9800 and 1400Arays wher they do have attenuation on the whole driver.

    That seem to indicate that the sensitivity is about where you predict POS, dropping with frequency and mitigated by beaming.

    I will look att my DSP settings later tonight.

    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

  10. #130
    Senior Member pos's Avatar
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    Quote Originally Posted by sebackman View Post
    Makes me wonder how they manage to get the top end in the S9800 and 1400Arays wher they do have attenuation on the whole driver.
    The impedance is rising from 7kHz up, so the series resistor will produce less and less attenuation at higher frequencies.

  11. #131
    Senior Member Anti K's Avatar
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    I'm confused:
    Is thats why UHF is 'the must' for Be HF because it rolls off at higher section,
    _______:and that's why is needed add a UHF what rolls off at higher section

    JBL with unlimited resurces and best ears didn't have enough resourses and ears to deal with this hole at 20k?

    A'bit more seriously, what would be a seriuos alternative into JBL original UHF horn instead 045.
    The ScanSpeaks and stuff, the graphs are even more ugly. Just with that exception, less sensi and less power handling - Grandma 's things.

    Or is - like strongly seems to me - the separate UHF time over, there comes one by one with dual ring radiators, the D2430, the D2415, all in new lenses.
    Do they image so much better or is it just money, the production process...

    Info from thread DD66000:
    http://www.audioheritage.org/vbullet...-finally/page6
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  12. #132
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    If the supertweeter response has a hole at 20K where nobody can even hear it - does it matter other than graphs?

  13. #133
    Senior Member Anti K's Avatar
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    Quote Originally Posted by JeffW View Post
    If the supertweeter response has a hole at 20K where nobody can even hear it - does it matter other than graphs?
    EXACTLY!
    But what if there would be another hole as well after 20k. A 'black hole'...
    But, what we know, when best ears put these things together.
    There is probably some delicious specified nuance we never reach in our lifetime, specially when listen music like that:
    (special attention at 8:30)
    https://www.youtube.com/watch?v=4emogJU_pdA

    Actaully I think DD66000 is weak for this.

  14. #134
    Administrator Robh3606's Avatar
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    I don't see the worry. What media are you using?? If it's CD anything above 20K is a moot point!

    Rob
    "I could be arguing in my spare time"

  15. #135
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    Quote Originally Posted by Anti K View Post
    EXACTLY!
    But what if there would be another hole as well after 20k. A 'black hole'...
    But, what we know, when best ears put these things together.
    There is probably some delicious specified nuance we never reach in our lifetime, specially when listen music like that:
    (special attention at 8:30)
    https://www.youtube.com/watch?v=4emogJU_pdA

    Actaully I think DD66000 is weak for this.
    Maybe JBL ears decided the supertweeter was too hot in the 20K range and engineered the dip?

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