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Design for JBL K140 115 Cab?

Discussion in 'Amps and Cabs [BG]' started by wisconsindead, May 19, 2017.


  1. I'm in the process of picking up some JBL K140's. I'm not entirely sure what to do for cab design. I plan to purchase two speakers and make separate cabs for each. Ultimately I am trying to replicate the sound of Phil Lesh's earlier cabs, while recognizing that there are probably some things worthy of improving with respect to the cabs they used back then. Any thoughts/ideas?

    Cheers.
     
  2. Steve

    Steve

    Aug 10, 2001
    I'd go through the JBL pro catalogue looking at cabs they have that use that speaker and build something off of their drawings. JBL has some pretty dang nice 115 boxes
     
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  3. kartiste

    kartiste

    May 5, 2008
    I just built a couple. Check my post Fat Man joins Little Boy. Presently preparing to retune one to 44hz to see how I like it compared to the other at 36hz.
     
    Last edited: May 19, 2017
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  4. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Be very careful about what you are buying, there are some really poor re-cones out there fetching money that is not deserved. Also be aware that even with factory parts you should respect JBL's power ratings closely as they are quite low by modern standards and the drivers are fairly easy to damage.
     
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  5. Do you know how to identify this?
     
  6. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Almost impossible, difficult even for a reconer unless that parts are obviously really bad. The looks are the easy thing to get right, the weight, geometry, dimensions and consistency are much more of a challenge. There are some really good aftermarket kits available, but it's something that a pro reconer will know about based on his professional relationships with his suppliers.
     
    wisconsindead likes this.
  7. Appreciate the reassuring info :p
     
  8. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    This is why those of us who do this stuff professionally are so wary... it's easy to get burned even if you know better...
     
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  9. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    Way back, mid Eighties, I built a 1x15 plus tweeter cabinet from plans in the Popular Electronics magazine. I built it for a keyboard player I worked with. He gave it back sans the woofer which he had sold to get drugs. That was another nightmare!!!!!

    i had available to me a JBL 2205 that had been re-coned with a 2225 kit so I dropped it in. It sounded superb! It was also old school built from 3/4 ply with heavy internal bracing - it weighed a lot. I gave the cabinet along with a lead sled power amp and an ART pre-amp to the children of a friend. They’re loving it and the three of them are learning to play bass very quickly. I also built the bass, a Jazz clone in black, to go along with the system.
     
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  10. So the only way to tell is if you already know the sound of a K140 well enough to know that's not what you're hearing eh?
     
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  11. What was it about the fearful 15 sub construction/dimensions that made you choose it over some other 15" box?
     
  12. kartiste

    kartiste

    May 5, 2008
    It was a flat pack I could buy (no table saw and local quotes were too high). But note, I modified the depth to be 0.75" less. It's still a little on the high side for a K140, but you can insert volume displacers to bring it down. I wanted to preserve the option of putting in a 3015 or 3015LF or 15PR400 later.
     
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  13. What would you change the depth to if you made it just for the K140 and not compromising?
     
  14. kartiste

    kartiste

    May 5, 2008
    I'd take an additional inch off the depth - 1.75" instead of 0.75".
     
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  15. jnewmark

    jnewmark Just wanna play the groove. Supporting Member

    Aug 31, 2006
    Stax 1966
    Play guitar.
    My favorite cab for JBL K140's was the old Kustom , Tuck n Roll 215. What a beautiful, sweet tone that cab had. Rated at 150 watts, with two of them, I routinely used all kinds of amps, including a pre/power amp rig of 1500 watts, with no problems. Of course, Agedhorse is right, they won't take a lot of power by today's standards, but, if you don't overdo it with the volume, or turn all the knobs to the right, it is a very sweet sounding bass rig. My old JBL info sheet says enclosures of 3 to 8 cubic feet is the ballpark. I love these 15's, and I would still be playing with them if they were not so heavy.
     
  16. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    I would recommend using the TS parameters and design the cabinet while paying close attention to displacement limits. This, plus using a 3rd or 4th order BW alignment filter, will get you more out of the driver with less risk.
     
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  17. jnewmark

    jnewmark Just wanna play the groove. Supporting Member

    Aug 31, 2006
    Stax 1966
    Play guitar.
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  18. kzr750r1

    kzr750r1

    Aug 12, 2011
    NorCal
    Look for the JBL 4625 enclosure to be a decent baseline. I have some E140 that need to be rehoused and this is the direction I'm going. Lifting two of these and the cab is just more than I want to lug these days.

    Spec for the cab is as follows. Now given this is with an E140.
    4.0 - Enclosure Volume (Cubic feet)
    40 - Tuned Frequency (Hz)
    Inside Dimensions:
    23.6 - Height
    19.2 - Width
    16.7 - Depth
    25.1 - Vent Area (Square Inches)
    (2) 4.0 - Equivalent duct tube and ID (inches)
    6.5 - Length (inches)
     
    Last edited: May 19, 2017
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  19. Interceptor

    Interceptor Supporting Member

    Mar 29, 2005
    Madison, WI
    I recently went down kind of the same road but instead of JBL took the Electro Voice path and rolled up a 1/2' plywood cabinet.

    I bought a reconed EVM-L from Midwest Speaker Repair and received an excellent driver. Aged horse is right about the older driver designs being lower power handling and easier to damage.
     
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  20. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    More or less, or run some parameter testing but that doesn't account for the all important mid voicing.
     
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