-3 db. @ 22 Hz. and enough output to commit a war crime:

Discussion in 'Speakers & Subwoofers' started by Kenneth Harden, Jun 15, 2005.

  1. Kenneth Harden

    Kenneth Harden Screenwriter

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    http://www.jblpro.com/pub/cinema/4642a.pdf

    I would totally go for it!

    Albeit, after amp and EQ, you are talking about a LOT of money. The unit is $1,900

    It would be interesting to hear it, shake the walls with 1/8" of cone excursion.
     
  2. ColinM

    ColinM Cinematographer

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  3. John Garcia

    John Garcia Executive Producer

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    And it's only 216lbs (240 shipped) [​IMG]
     
  4. Garrett Lundy

    Garrett Lundy Producer

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    Price? Theres some heavy competition in the $5000+ range
     
  5. Jesse Sharrow

    Jesse Sharrow Supporting Actor

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    Bah! 22hz. [​IMG]
     
  6. John Garcia

    John Garcia Executive Producer

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    SVS B4+ with two port plugs is [email protected] $2400.

    That guy says 131dB max SPL, but it won't get down below 20Hz (-10dB @ 20Hz), so it drops off very quick below 22Hz.
     
  7. BrianWoerndle

    BrianWoerndle Supporting Actor

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    My dual SVS 16-46CS+s are flat down to 13hz and only cost $1600.
     
  8. Mark Seaton

    Mark Seaton Supporting Actor

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    Ahhh, the joys of deciphering the common pro-audio spec sheet.

    First, what is listed as "maximum output" is just calculated, not measured. Working from their sensitivity spec which only notes down to 40Hz, combined with the compression factors, you see that even at 40Hz they are more in the ballpark of 126dB with 1200W drive level. Not very much by pro standards. Now consider that response is about 3dB less at 35Hz, and at least 10dB less at 22Hz without consideration of any vent/port compression. It still delivers fairly well for its cost, but it's no home-wrecker. If you look at the frequency response, and knowing how specs from the big pro players are skewed to look better, I suspect those numbers I just worked out are a bit optimistic. While I'm sure the power rating of this sub is considered for its 4 Ohm nominal load, I would wager that the sensitivity is for 2.8V, which is 2W into a 4 Ohm nominal load, making for a 3dB optimistic calculation of maximum output. The spinning never ceases...

    On the SVS B4+, it is certainly a monster that should likely out-woof the JBL here below 30-40Hz, but I don't know where you came up with 122dB @ 16Hz? I could believe that sort of output near 25Hz with all 4 ports open, and I believe Craig Chase found it do produce near 118dB in the 20Hz tune. That said, you didn't mention conditions of that performance, where a solid corner certainly offers the potential of that at some modest distance.
     
  9. John Garcia

    John Garcia Executive Producer

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    That spec came directly from the SVS manual for the B4+. It said single sub, corner loaded in a typical room. 20Hz tune was given as 126dB. These are their numbers though, so I can't validate them.
     
  10. Mark Seaton

    Mark Seaton Supporting Actor

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    Corner loading better explains the numbers. Do realize though that the JBL and most comparisons are specified at 1m 1/2 space, which is the same as 2Pi space or "ground plane." An ideal corner would be 12dB louder than a 1/2 space measurement. Corner loaded measurements are very difficult to take in any consistent manner from location to location as the ceiling height will be different, and the room will inevitably impact the measurement. Even in large spaces where the room is not a problem, then the height of the walls limits the accuracy of the measurement. In cases where a design benefits different than other subwoofers from corner or near-wall placement, you can measure this outdoors with 4 or 2 subwoofers respectively, then scaling back the output for comparison to a single sub in 1/2 space.
     
  11. Greg Conti

    Greg Conti Stunt Coordinator

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    I ran a 4645B version for a few years in my setup. No output below 20 Hz but that ok with me as I don't care about that. If you know someone, you can get pretty good deals. The 4645B was around $700. I paired that with a used Macrotech 1200 I picked up for $500 and had some serious output for $1200. I never once overdrove the thing. Never once saw the 1200's clip. And thats with one 18" woofer. The 4642 would be even more impressive. That was pre SVS and the like days though and high output subs were rare and expensive.

    I did grow tired of the size of the thing though. They are big and ugly. These days I'm running a DIY 15" with dual PRs tuned to 20 Hz in a much smaller box. Funny thing is my girfriend got upset when I got rid of the JBL.
     

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