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Thread: How to get real 16Hz...

  1. #1
    Senior Member Ralf's Avatar
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    How to get real 16Hz...

    In the threat "I would like to introduce myself." you can see my system.

    Everything sounds very fine, but naturally the rear loaded horns like 4530 have a delimitation in the range starting with 50 Hz.

    So my idea is to create a subbase (vented box) which goes down to 20Hz (16Hz/-3dB).

    This stage should insert itself harmoniously into the existing sound.
    That`s not so easy, because the 4530 have an enourmous sound pressure.

    The best way should be 4 18" Shearer Horns, but this dimension are too large for my small home (and it`s also not possible to go down to earthquake-frequenzies)....

    The highpass cutoff should be 50Hz, aktive separated.

    Has anybody build a system, which goes down to these deep frequenzies?

    Is it possible with 4 2245H?
    (my software said no....)
    Last edited by Ralf; 11-10-2003 at 04:14 PM.
    16 Hz can not be substituted

  2. #2
    TimG
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    You probably won't be interested since this design doesn't use JBL drivers. This is a free horn design from Tom Danley, the product engineer for Servodrive/Sound Physics Labs.
    This horn design can reach 16Hz, in a home setting, with proper equilization. It was designed to be used 4 per side if used for live sound reinforcement. Here are some links
    LABsub design
    http://www.prosoundweb.com/lsp/
    LABsub discussion forum
    http://www.prosoundweb.com/community/forum.php?board=3

  3. #3
    Alex Lancaster
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    Smile

    Tim:

    I canīt download the links.

    Alex.

  4. #4
    Senior Member Ralf's Avatar
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    What should I say to these horns...

    look at your own:

    output
    16 Hz can not be substituted

  5. #5
    Senior Member Ralf's Avatar
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    Hi, Giskard

    the 4645C could be a beginning for my consideration.

    I have not found anything about the 121H. Do you have a link to a spec file?
    16 Hz can not be substituted

  6. #6
    Senior Member Ralf's Avatar
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    Hi Giskard,

    I believe, that the JBL/Urei 5234A Network has a jumber inside to cut such subsonic frequencies. But I can`t find the users manual at the moment.

    if you have 4 18" cabinets, it should be possible to get a win of 12dB. Is it right?

    With a little bit equalizing it could be reached the magic border line down to 20 Hz...
    16 Hz can not be substituted

  7. #7
    TimG
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    Using Unibox, with a pair of 2245H in sealed boxes with at least 4.8 cu ft per driver, I get 104.5 dB at 16Hz at 1M, before room gain, at xmax. If you your room has rigid walls and you place the drivers together in a corner I would expect at least 112dB at 16Hz.

    With 4 drivers you are looking at 110.6dB anechoic at 16Hz. THis would give you close to 120dB with room gain. You would be hitting 120dB anechoic at 27.8Hz.

    These models do not account for driver compression and it does not tell me how much power it takes to hit xmax.

  8. #8
    gyusher
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    Watch out

    Better watch out for the "Brown Note". . . .LOL. . .

  9. #9
    Senior Member GordonW's Avatar
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    Speaking, as TimG was, of Tom Danley...

    If the LABHorn sub isn't enough, then you could always hunt up the parts to put together one of Danley's "Contrabass" servo-motor subs. ONE of those, will put out 120dB @ 20 Hz, in free space!!

    There's a fellow around here, that used to have TWO of these in a home living room. He claims that this sub setup managed to crack EVERY LAST drywall joint in his house, and stated that the drywall ceiling fell in on him once, due to the bass.

    THAT is "enough output", I'd think...


  10. #10
    Alex Lancaster
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    Smile

    Gordon:

    Where do We get more info on the Servo motor bass?.

    Alex.

  11. #11
    TimG
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    The website is www.servodrive.com
    Here is the link to the contrabass http://www.servodrive.com/contrabass.html
    About 9 years ago Tom convinced his boss to let him offer the parts to build your own, but that offer didn't last very long. Tom Danley suggested that you could build something similar using a pair of 12" Labsub drivers and 2 15" PRs per box, here is the link

    http://db.audioasylum.com/cgi/m.pl?f...vo&r=&session=

    PM me if you want more info, since this topic is not about JBL drivers.
    Last edited by TimG; 11-11-2003 at 09:02 AM.

  12. #12
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    "I believe, that the JBL/Urei 5234A Network has a jumber inside to cut such subsonic frequencies. But I can`t find the users manual at the moment."

    5234A Manual

    5235 Manual

  13. #13
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    Re: How to get real 16Hz...

    Forget I mentioned the 121H. It's too difficult to explain how to employ it. Besides, it simply isn't efficient enough, even in quantity, for your particular application. Forget I mentioned the 2245H as well. It's also too difficult to explain how to use it.

    You can buy or build a few 4645C's, and EQ them if desired, or you can go out and buy any of the other fartknockers currently on the market for significantly more money.

  14. #14
    Niklas Nord
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    What would be possible with a TacT RCS 2.2x and two or
    four JBL 2245H ?

    It would be possible to put the 2245īs in sealed enclousures
    and EQ it down to 20hz.. And put them in corners..

    Or would it not?

    If we then hook this up to an ampfilter capable to deliver
    1200watts into the 2245īs...

    THAT would be something

  15. #15
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    It has been my experience that the 2245H in a sealed enclosure doesn't necessarily need electrical EQ nor does it need to be specifically placed in a corner. In general, the 2242 is easier to boundary load than the 2245. I almost always employ a minimum of two subs regardless of diaphragm size.

    A 2245 in a sealed enclosure gains some protection from the restoring force of the trapped air and won't unload below resonance. It has significantly less group delay. It ultimately extends much deeper than it's ported counterpart. It EQ's (EQ here refers to natural room rise) naturally with a typical room more successfully. It's transient response improves significantly. It's intermodulation distortion is greater at the same frequencies that it's ported counterpart is tuned to. It's efficiency is significantly lower as well. In short, it is my personal opinion that it is excellent for a typical home listening environment and less than ideal for situations demanding maximum SPL in the VLF.

    *****

    For clarity
    Last edited by 4313B; 11-11-2003 at 05:36 PM.

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