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JBL k140's

Discussion in 'Amps and Cabs [BG]' started by cptripps, May 4, 2010.

  1. cptripps


    Nov 29, 2009
    Coventry RI
    I picked up a pair of vintage (circa 1979) JBL K140's in old Sonic 1X15 stackable cabs today. The speakers are both original never re-coned and with sequential serial #'s. The cabs are very clean and solid too. The only thing I immediately noticed after a few thumps on the old bass was was that the speaker inputs were polarity reversed. JBL uses the Black positive convention but the person who put these together didn't seem to know that.

    After a quick switching of the input wires I hooked them up. Whoah!

    The first head was, umm, my first head ever, a crusty old Kasino (Kustom) 200. Terrifying lows and smooth overdrive. I'll find uses for this new tone in my studio.

    Second head was my trusty Hartke HA3500. Tube pre at 3 o'clock, SS pre off, EQ out and countour controls flat. Holy yikes, I couldn't it past 3 without my heart skipping beats.

    Price paid was $300 for the pair, the guy even delivered them from 2 hours away. Thoughts and opinions are well appreciated, these are my first JBL's and so far, I'm smiling like a fool! :bassist:
  2. username1


    Dec 28, 2005
    alberta canada
    I always loved the sound of old jbl's. As far as the phasing goes it doesnt really matter which way you connect the leads as long as both speakers are the same and your not using it with another non jbl cab. Its probably a good idea to reverse the wires like you did incase you ever use the cabs with other non jbl's but I cant really see how switching the polarity made a difference in sound if they were already in phase with each other? Should sound exactly the same. Great buy though...congradulations!
  3. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    good score! i keep threatening to do a similar thing but i keep doing other stuff instead.
  4. edbass


    Nov 8, 2004
    Great Score!

    The D140F is probably the best sounding, most musical bass driver IMO, but I prefer the K's because of the trade off with power handling; they can take a pounding better and are almost as "sweet" as the D's.
    Neither of them will handle the power that even most inexpensive modern drivers will, but in the right cab IMO they sound absolutely phenominal, particularly with a nice tube amp driving them.
    Also, aside from sounding great, a pair of them will get plenty loud.

    I have a Sunn 2000S rig with a pair of K140's; a meager 150 watts into a pair of ancient drivers rated at maybe 125 watts or so, and it will literally flap your pants legs, tickle your junk and make ceiling tiles "snow". ;)
    There's a reason why the big Sunns had this label on them;


    You just have to wrestle with a near 200 lb rig and have a vehicle big enough to carry a coffin to use it!
  5. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Thousand Oaks, CA
    John K Custom Basses
    K140's are still my favorite sounding 15" speaker, and is probably the reason that i have six of them. they handle 150 watts (continous sine wave) so they're capable of handling quite a bit of power, and since they're efficient, two of them is more than enough for all of the large clubs and huge banquet rooms that i've played in, even with no FOH support.
  6. AlexanderB


    Feb 25, 2007
    And IMHO, JBL is also conservative in their power ratings. I have never been worried to burn the voice coil of speakers from JBL, EV, or Ciare. In spite of all new products, many will keep on using the D, E and K series along with their counterparts from EV, Celestion etc. That classic tone is right there.

  7. Bassmec


    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    I still think the Jbl D/K or E are among the top 1% of the best sounding fifteen inch bass guitar speakers I have ever put mic's to.
    The only other contender to my old K140's is the Altec Lansing Alnico 418 Series 11 in the original Ampeg tin badge SVT 115 cab.
    OK these speakers are very old, have not that much X max don't claim to handle the best part of a kilowatt, as is the norm today?.
    BUT stand a modern Ampeg 115e against one in an AB test and the modern plastic badge cab will sound boomy, dull, lifeless and not very loud at all in comparison.
    How things have improved!:rollno:
    PS. Maybe we should all club together and get JBL to make Bass guitar speakers again only problem is James B Lansing, the geezer what seemed to really know about these things is brown bread mate.:bawl:
  8. Bassmec


    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    CP tripps you got a absolute steal because in europe those k series 15's would have gone for almost twice that on flea bay.
    Here is a current auction for a 12" D120F.
    PPS So if these things have so little power handling, how is it that so many of them are still working fine with the original cones in, in this case after over 30 Years of service?.:meh:
  9. cptripps


    Nov 29, 2009
    Coventry RI
    Wow I guess I did okay on that deal :)

    My thought on the polarity thing was motivated by recording and mic phase. by way of example, when I kick the bass drum my studio monitors push air out so translating that to the JBL's, when I hit a bass note, I also want the studio monitors to push air out. Other than that I guess if I mixed one with a different cab there would be some phase cancellation.

    Sort of rambling here and I am no expert on such things but I also wondered if the cones had more free travel moving away from the frame rather than towards it? I had a horrible thought of the cone retracting into the frame and the voice coil frying. Granted that would probably take a synthesizer hammering the lowest C or something but again, I get paranoid...

    Well thanks everyone for the feedback, I feel a little more justified in parting with the cash during these tough financial times. So far I'm very pleased, I'll be recording some bass tracks today in the studio so I'll know all about these cabs by the end of the day.
  10. coreyfyfe

    coreyfyfe Supporting Member

    Nov 19, 2007
    boston, ma
    I really like the sound of these JBL speakers. I recently picked up a 65 ampeg B15 which came loaded with a K140. I wasn't sure how it would sound, but I'm really digging this amp with the JBL in there. I'm not sure if it's the circuit revision, cab porting change, or the JBL speaker, but this B15 vs my old stock 68, the 65 wins by a mile.
  11. jnewmark

    jnewmark Just wanna play the groove. Supporting Member

    Aug 31, 2006
    Stax 1966
    Third St. Cigar Records staff musician.
    Although I like the E140's better for more power handling, they are heavier than the K's. I'm actually having Don at LDS build me a 215 cab with K140's and a Schroeder type horn, sort of a poor man's BMF 215. Don is thinking about building one for himself, and I will supply him with two K140's I had left. I also put a K140 in my Roland DB 700 and the tone is just to die for. Can't get loud with these drivers, but most of my gigs don't call for big volume anyway, and with my Jazz, it's a tone that I have never found with any other brand of 15. I recently found a NOS pair on Craiglist, still in the boxes ! Sadly, JBL decided to discontinue their Musical Insrument Speaker line some years ago, but you can still get them reconed as the kits are widely available.
  12. nysbob


    Sep 14, 2003
    Cincinnati OH
    The fact that so many people are still using and loving the sound of these drivers 30 years after they were introduced is a real testament to their quality. The modern stuff may handle more power and move more air at a lighter weight, but I've played the 3015 in a few different cabs, and to my ear they don't have the sweetness.

    If JBL had a clue, they would do it again.
  13. Hey, it was his choice!
  14. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Thousand Oaks, CA
    John K Custom Basses
    OC speaker, which has been a factory authorized JBL speaker repair center since the 60's, told me that if a K140 needs to be reconed, JBL uses the E140 kit. they also said that it doesn't change its tone but does allow to handle the additional 50 watts of the E series, which is a 200 watts rms continuous sine wave. one of my 3 pairs has E kits in them, and i have to agree, they sound just like my other two pair of NOS ones.

    and i also agree with nysbob that they sound ALOT sweeter than the modern Eminence 3015.
  15. D.M.N.

    D.M.N. (O)))) Supporting Member

    Oct 6, 2008
    Los Angeles, CA
    ERG! These are exactly what I've been searching for to finish up my Sunn project. I've contacted a few people who have listed K's for sale, and no one's gotten back to me yet. But I cannot wait until when I do finally find them.

    Just checking, but with two of them wired up in a cab, they can handle 300 watts yeah? I don't want to put them in, turn up and then blow them. That'd be a crying shame!
  16. LoveThatBass


    Jun 28, 2004
    I had a pair of JBL D-140F's. They require a smaller cab than most other speakers. Until you push them to their limit of travel which for a bass speaker is about 3.2mm compared to 5-9mm for other bass speaker they have a beautiful tone. Heavy as heck though.
    It will surprise you at the low end you get with a very modest amount of volume but when you crank it up expect them to compress some and fart out.

    I do not know why JBL insists on doing the reverse polarity thing but I use a 9volt DC battery and hook it to the speaker. If the cone moves out you have the polarity correct. If it pulls in you have the polarity reversed.
  17. nysbob


    Sep 14, 2003
    Cincinnati OH
    No, they won't handle 300W. :rolleyes:

    They don't NEED 300W. This is why they work so well with an older tube head. You can use a 300W amp, but you need to pay attention to what they're sounding like...you probably will not need to run as much gain on the amp as you're accustomed to.
  18. I'll have to chime in here, proclaiming my love for K-140s as well!! For many years, I used two or more in all kinds of cab configurations. As a matter of fact, through most of the eighties, I wouldn't use anything but. I still have two of 'em left, with dust covers dented, or cut completely away, but just can't carry the weight anymore.

    Hey, wouldn't it be a great R&D goal to see Eminence develop a Neo version with high performance parameters, but capturing the tone of a K-140? I'd sure hook up on a 2x15 cab like that!!! :hyper:
  19. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Thousand Oaks, CA
    John K Custom Basses
    a pair of K140's will handle 300 watts easily. i've run a pair of mine with a GK 1001RBII (700 watts) at very loud volumes with no issues whatsoever.
    IMO, JBL rates these driver VERY conservatively.
  20. +1.....I've never blown one and have played literally thousands of high powered gigs with 'em!!

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