Maxn Posted May 14, 2015 Share Posted May 14, 2015 HI all have any of you an y experience with the old JBL K140's? I'm thinking of making a 2x15" cab to match my Acoustic 370. Can't find the original matching cab and want to build a cab styled the same as the original acoustic cab with some vintage K140's. Could be any other speaker but its the K140 that was used allot in the 70's for bass so was after the old school sound! Any thoughts? Quote Link to comment Share on other sites More sharing options...
Balcro Posted May 14, 2015 Share Posted May 14, 2015 (edited) hello Maxm, This site will be good for starters - [url="http://unofficialacousticcontrolcorpmessageboard.yuku.com/directory#.VVUexpM3R_k"]http://unofficialaco...ry#.VVUexpM3R_k[/url] Also try searches on JBL K140 - they're prized treasures for some people. You may also see modern comparisons on the usspeaker.com web-site. Balcro. PS. Oh, and this - http://www.jblpro.com/pages/obsolete.htm Edited May 14, 2015 by Balcro Quote Link to comment Share on other sites More sharing options...
stevie Posted May 15, 2015 Share Posted May 15, 2015 I had one up to a year or so ago. It's a great-sounding speaker. However, it does not have the extended HF that you might expect from the aluminium dome. You won't find any frequency response measurements for the K140 anywhere, but I measured mine (which was brand new) and it rolled off around 2kHz (from memory), which surprised me. It also won't handle as much power as a modern top-or-the-range driver, but if you're using two it will be plenty loud enough for almost anything. Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted May 15, 2015 Share Posted May 15, 2015 The K140 will give best results in a 2 cu ft (net) box tuned to 30Hz. A single 3 inch ID tube 8 inches long will suffice, as with the 150w power handling it won't create sufficient port velocity to result in chuffing. Quote Link to comment Share on other sites More sharing options...
tonewheels Posted May 15, 2015 Share Posted May 15, 2015 Norm used 2 x K140 for a long time with his Trace head. If it's good enough for Norman..... Quote Link to comment Share on other sites More sharing options...
VTypeV4 Posted May 15, 2015 Share Posted May 15, 2015 I have a K140 however it's waiting for a recone.. I do have a D140 which is very similar and is lovely for oldskool sounds. As above, it doesnt have that super bright edge you might expect but it is a very clean sounding speaker.. If you get a pair, follow Bills advice and you'll not go far wrong. Quote Link to comment Share on other sites More sharing options...
Balcro Posted May 16, 2015 Share Posted May 16, 2015 Well, lookeee here Maxn! Guess what I just found by asking Jeeves. http://www.jblproservice.com/pdf/thiele%20small%20parameters/theile%20parameters.pdf Balcro. Quote Link to comment Share on other sites More sharing options...
Maxn Posted May 17, 2015 Author Share Posted May 17, 2015 Cheers for all the info, the ironic thing is I did have a pair of these years ago in a pair or Court Accoustics "Black Box" W bins. But they were just used as bass bins with my pa, sold them for something smaller! They were huge. Sounded great. But never played my bass through one. Anyhow will keep an eye out. I still think these older speakers will be a good match for the accoustic! Quote Link to comment Share on other sites More sharing options...
stevie Posted May 18, 2015 Share Posted May 18, 2015 (edited) When you do build your cabinet, I'd strongly advise you to have a look at JBL's own plans for these drivers. The 2 cu. ft. or 55 litres that Bill suggested will work, but will be a bit bass light - around 80 litres would be better. Also, you need to tune the box to between 45 and 50Hz, preferably using 4-inch ports. If you tune it to 30Hz you will most likely blow your drivers. JBL suggests a volume of 3.75 cu. ft. for a single driver and 5.75 cu. ft. for two - that's 105 and 162 litres. I personally would stay at the lower end of that range because a smaller box will help power handling a bit and going any larger doesn't really get you any extra bass. There is plenty of discussion on the web about the K140 (lots of positive comments from bass players) and if you search you'll find quite a few plans. The JBL ones are here: <http://www.lansingheritage.org/html/jbl/plans/1970s-kit.htm>. Good luck! [Edited to fix the link.] Edited May 18, 2015 by stevie Quote Link to comment Share on other sites More sharing options...
JTUK Posted May 18, 2015 Share Posted May 18, 2015 I ran K140 and D140's in a 4560 bin with some tops with bass and the sound was huge... Not the bass sound that you'd be able to use, mind, but good fun at the time. Quote Link to comment Share on other sites More sharing options...
VTypeV4 Posted May 18, 2015 Share Posted May 18, 2015 [quote name='JTUK' timestamp='1431974923' post='2776874'] I ran K140 and D140's in a 4560 bin with some tops with bass and the sound was huge... Not the bass sound that you'd be able to use, mind, but good fun at the time. [/quote] Hey John, the K140 is still needing a re-cone but the D140 is running just fine.. Hope you're cool. Sorry for the thread jack! Quote Link to comment Share on other sites More sharing options...
JTUK Posted May 18, 2015 Share Posted May 18, 2015 Hi Matt. excellent, yes, all good here...and you? Great full sound for vox thru the Bins and tops. Singers loved them. Big heavy cabs tho.... Quote Link to comment Share on other sites More sharing options...
jensenmann Posted May 22, 2015 Share Posted May 22, 2015 (edited) [quote name='stevie' timestamp='1431967059' post='2776717'] When you do build your cabinet, I'd strongly advise you to have a look at JBL's own plans for these drivers. The 2 cu. ft. or 55 litres that Bill suggested will work, but will be a bit bass light - around 80 litres would be better. Also, you need to tune the box to between 45 and 50Hz, preferably using 4-inch ports. If you tune it to 30Hz you will most likely blow your drivers. JBL suggests a volume of 3.75 cu. ft. for a single driver and 5.75 cu. ft. for two - that's 105 and 162 litres. I personally would stay at the lower end of that range because a smaller box will help power handling a bit and going any larger doesn't really get you any extra bass. There is plenty of discussion on the web about the K140 (lots of positive comments from bass players) and if you search you'll find quite a few plans. The JBL ones are here: <http://www.lansingheritage.org/html/jbl/plans/1970s-kit.htm>. Good luck! [Edited to fix the link.] [/quote] +1 I had a K140 mounted in a 60s Fender style closed 1x15 cab. This combination couldn´t deliver what the speaker is capable of, sounding small and bass-shy. Later I got the original JBL cab which is double volume and ported. That was a revelation. Now it goes lower than my Boogie 1x15 (EVM15L). To me it sounds well balanced and I don´t miss any treble. I don´t do slap stuff, though. Good enough for finger and plec sounds with my tube heads. In the meantime I stuffed the other cab with a D140F which seems to be a perfect fit. This one still has a lot less lows compared to the JBL cab but it sounds organic with a very different character. Edited May 22, 2015 by jensenmann Quote Link to comment Share on other sites More sharing options...
Taryn Jordan Posted November 20, 2019 Share Posted November 20, 2019 What would the ideal amp wattage to use with a jbl k140 1x15" bin ? Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted November 20, 2019 Share Posted November 20, 2019 There is no ideal amp wattage, for any driver. The usable range tends to be between half and twice the driver thermal rating. For a K140 that's 75 to 300 watts. Quote Link to comment Share on other sites More sharing options...
agedhorse Posted November 20, 2019 Share Posted November 20, 2019 Note that for musical instrument use, JBL recommends between 1/2x and 1x the thermal rating depending on how it's being used. See section 4 which covers the applications that would apply to bass guitar. https://www.jblpro.com/pub/technote/spkpwfaq.pdf 1 Quote Link to comment Share on other sites More sharing options...
BO AUDIOMAN BORIS Posted May 27, 2020 Share Posted May 27, 2020 hi Folks, I have 4 pairs of jbl K140. i would like to build 4 vented cabinets with on each 2 x k140 bass 1 x 2123h bas mid 1 x altec 808 a8 ALNICO + 511 horn high mid 1x 2402 ALNICO high 1x 2405 ALNICO super high. A friend of mine advised me a size of 364 litres ( L 110 cm x H 75 cm x D 44 cm ) inner volume. Concerning the duct, he told me that the best suitable duct dimension is Sd 180 cm² (L 21.4 cm x H 21.42 cm and 18 cm maximum Depth). Cross over (intertecnik/sprague/m cap supreme 18dB / way with Lpads (die cast aluminium resistors on 808a ; 2402 + 2405 + rotative attenuators on 808a ; 2402 + 2405. I would like to know i i have to/must align all the components from the emmisive part of the diaphragm / cones? Are the dimension of the box considering all the component? Is the duct mouth en length ok? Thank you all in advance for repliyng. Sorry for my poor English (Belgium). Regards Boris Quote Link to comment Share on other sites More sharing options...
Balcro Posted May 29, 2020 Share Posted May 29, 2020 (edited) Wow! What a collection: 5 drivers. The K.140 is quite adaptable. BFM's post from May 2015 will give a long smooth roll-off at the bottom end. If you want more low bass, then a single K140 will still work happily in a 2cu.ft (56 litre) enclosure. So two K.140's will require 112 litres or thereabouts. Port size and length are dependent on your choice of enclosure size. For example, with 2 x K.140's in a 112litre enclosure, winISD suggests a 12.5cm square duct but only 4.5cm long. The 2123 bass /mid works in a closed box of 7 - 14 litres. Frequency response is from 80Hz to 6K, although the recommended crossover is 3K. The Altec 808 compression driver works from 500Hz - 20KHz. You'll certainly need an attenuator to match it to the bass and bass/mid. Whether you need the 2402 and the 2405 is questionable with the 808 extending to 20K. Whatever size you choose, you need to reserve 15litres for the separate midrange box, 6 litres for the internal volume taken up by the two K.140's, 1 litre for the 808 compression driver and 0.5litre for the internal space taken up by the duct. Edited May 29, 2020 by Balcro Quote Link to comment Share on other sites More sharing options...
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