JBL K-140 CAB BUILD

Discussion in 'Amps [BG]' started by jnewmark, Sep 18, 2009.


  1. jnewmark

    jnewmark Supporting Member

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    I 've got a really mint K140 that's been sitting around for years,and thought I might have a cab built for it, maybe a 2-way or 3-way? Some DIY'ers on a JBL message board suggest that a 4 cubic ft cab, with the K140 running wide open with a rolloff to a HF driver, instead of a crossover. I would'nt be putting more than 300 watts into it. I know the JBL's don't get much love here, but, I would still like to hear what this 15 would sound like in a proper cab, with a tweeter or horn. Suggestions? No snarky remarks , please? :bag:
     
  2. topcat2069

    topcat2069 Supporting Member

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    I had a DIY 2X15 Cab made for D-140s and the thing ROCKED big tight lows, smooth mids and enough highs that I didn't need a tweeter. Of course this was back in the '70s / '80s when Bass Rigs didn't use tweeters. As I recall, the builder got the plans from JBL.

    I was driving it with an Acoustic 450
     
  3. Bassflute

    Bassflute

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    are a full range bass guitar (sic) speaker, not really designed for use with crossover, mid drivers, horns, and the like. They have nice soft, deep low bass, and a very smooth and sweet lower midrange, a sound that is kind of iconic and lovely once you hear it (I had two large 15" cabs back in the early 80's). The high mids and highs can get quite 'clacky', for lack of a better term, like a Fender maple-necked bass with really old nickels on. Some back in the day attenuated it somewhat by replacing the 'titanium' dome (it's really aluminum, I think) with a paper/fibre one. But to use that speaker well in a three way system would be tricky, as it already covers well into the 4-5K range I believe. A two way would probably be better.

    Just my estimates based on an almost 30 year old recollection - don't jump all over me if my numbers aren't perfectly accurate.

    Cheers,
    Cameron
     
  4. 4Mal

    4Mal Supporting Member

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    You sure won't put more than 300 into that cab - 75 to 125 clean is more like it ... IIRC 4.5 cu ft, and 2 4" dia 10" long round ports is the spec for the old JBL Cabaret 1x15 cab.

    Dude... I'm an old JBL fan. Spoken form the heart... dump it, get a 3015 and do a nice small 'reasonable' cab. What you're after is a waste of wood and time in comparison - though it does pain me to say it. Time to move on ... by way of reference, a 3015 in 2.6 cu ft will go deeper, go louder, sound better in about half the space, and less than half the weight.

    Or you could go the full enchilada and snag the plans for a 4' tall 1x15 scoop. They are floating arouns on the net somewhere I believe. I used a pair of those as my side stage rig back in the early 80's. (We were after a nu-wave, no amps on stage, stage set kinda look...thankfully we waved off the flock of seagulls hair ...:D)
     
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  6. jnewmark

    jnewmark Supporting Member

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    that's cool, I was originally thinking of a two way cab. I am familiar somewhat with the old JBL 15's. I used a pair of E 140's for 20 years. I always wanted to add a tweeter to the cab when popping-I like that sound of a tweeter when playing that style. what exactly does a rolloff do as com pared to a crossover? Would this give me that sparkle on the high end?
     
  7. jnewmark

    jnewmark Supporting Member

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    Yeah, I hear what your saying, and I knew someone was gonna bring up the Eminence. I already own the K140 and I love the JBL sound, especially. I may just throw it in an existing 15 cab and see what I got. Probably will be a practice rig anyway.
     
  8. johnk_10

    johnk_10 vintage bass nut

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    i've run a pair of 3015's in a couple of my 2-15 cabs. they were okay, but i think that the K140's sound ALOT better. they may not handle as much power, but have an uncanny smoothness and roundness to their sound. to me, they're magical. the 3015's sounded kinda like they had cardboard cones by comparison (too stiff sounding),and one dimensional, hence i sold the 3015's and now have three different 2-15 cabs loaded with two K140's. just my opinion.
    my current JBL K140 cabs are:
    an early Sunn 2x15 (middle port)
    a vox beatle cab from nothcoastmusic 2x15 (added round ports)
    and a fender 2X15 (non ported - diagonal mount). all of them sound great with the Sunn having the most volume and throw.
     
  9. INTP

    INTP

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    I'd put it in a cabinet, for the vintage tone! I'd probably skip the tweeter, but you could always install one with a switch to disable it if desired.
     
  10. gerryjazzman

    gerryjazzman Supporting Member

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    I had an old Acoustic 2x15 cabinet (406?) years ago that I used with a V4B. It came with some crappy replacement speakers and I bought a pair of K140's to replace them. They sounded superb to my ears. They shook the windows in my house and they did have beautiful mids and even some sparkly highs (yeah I know they probably beamed like hell). I also used that amp and speaker combination with a Fender Rhodes piano and it sounded wonderful. If the drivers are in good shape I think they are worth using. I do have a BFM Omni15 Tallboy that is great (uses a 3015LF) so I can appreciate the new technology, but the K140s if in good shape do sound good. Don't drive them with a kilowatt amp though.
     
  11. jnewmark

    jnewmark Supporting Member

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    Now I wish I had two! Really hoping to find a nice 115 cab now and just switch out the 15. I used 2x15 cabs for years with E140's but never tried the K140.
     
  12. BassmanPaul

    BassmanPaul Gold Supporting Member

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    Getting the best out of any speaker requires that it be installed into a suitable enclosure. Just because a cabinet has been designed around a 15" driver doesn't make it suitable for your JBL. It might work out OK but it's just as likely to be a death sentence for your speaker.

    Paul
     
  13. lbwdog

    lbwdog

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    Jnewmark;
    Them old birds are pretty tough. i used K140s for years in all type configurations. Singles, pairs, etc. Never blew one.
    Got one installed in an 80's Carvin B-115 cab, and sounds fine.
    I like the tone of Ks better than an E or D.
     
  14. joegeezer

    joegeezer

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    Looking at Win-Isd, I'd guess on a little 2cu.ft. box, tuned to 40 hz. Too bad it's not a K-145!
    Send a PM to BGavin, he's the JBL guy here on TB.
     
  15. johnk_10

    johnk_10 vintage bass nut

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    i've yet to blow one too. i also like the K series the best.
     
  16. jnewmark

    jnewmark Supporting Member

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  17. GlennW

    GlennW

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    I'd build one of these and stick it in there.
     
  18. billfitzmaurice

    billfitzmaurice

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    Until the introduction of the E series all JBL drivers were originally intended for use in traditional 2 way and 3 way systems; the K series were so employed in the Cabaret cabs of the late '70s. With the advent of the E series circa 1980 JBL started making their own woofer only cabs, but they also used E series in 2 and 3 ways, including the Cabarets. When the 2200 series used the E chassis with paper domes instead of aluminum that finally differentiated their instrument series from PA/hi-fi. All traced their heritage to the D130, which was introduced circa 1949 as a hi-fi speaker.
     
  19. jnewmark

    jnewmark Supporting Member

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    Over on the above mentioned website, it was suggested that I, " run the K140 wide open and roll off to the HF driver " What exactly is " rolling off " ?
     
  20. edbass

    edbass

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    Nov 8, 2004
    Exactly what he said. ;)

    I have that exact cab loaded with a K140 sitting next to me in my office as I type this. I have a late 70's B15N head sitting on top, and the combo sounds great together.
    The cab is a late 60's Sunn l-40, or an early 70's 115S. They pop up on ebay and Craig's list periodically, and are a nice little cab but will only take an AlNiCo JBL or other similarly shallow basketed driver.
     
  21. GlennW

    GlennW

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    Sep 6, 2006
    I saw a picture of a 200S or 2000S cab which had the angled boards notched to allow for larger magnets/frames. The speakers were in there, but I don't know how it sounded.
     

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