Difference between the D series & K series JBL speakers?

[Gerry D]

...they are heavy enough without the added 35-40Lbs. of JBL's...A good move if you have a road-y...I have been playing bass guitar for years...JBL- GAUSS- ALTEC are all I will use...moving the weight without the the efficient speakers is a waste of energy (In more ways than one)...more sound pressure for power in...High quality pay it's own way...BUT the twin in too heavy to begin with...and the open back kills the low end...

The basic bass stack:

TWO-K-140 in 200OS cab
TW0-8840 18" Gauss in two 8.5 ft cubic Completely enclosed cabinets
Four-2842 Gauss 12' In to "Alembic hard trucker cabs 4.5 ft cubic completely enclosed each.
One-(not the "good stuff) Guild Hartke 4-10" trans-response cab.

There is more (two K-120's in the Stars Guitars 5 ft cube cab...[seldom used]) but I find I've got it all covered...but not too many places to take advantage of the capabilities.

[Gerry D]

I bought a new pair in '75, after having been exposed to a pair a bass player friend of mine had. I lost one to a comparison test with a Peavey 1501, around '80. (Salesman said the ALU dome was integral with the coil former to allow better heat conduction and dissapation, seemed to be true, but of course there's no way to center the coil from the front, which is why Peavey's have the removable magnet. I bought 4 1501's in '80, have yet to burn one out...) I ran the K's in 2530's, along with a bunch of D's, the 1501's lived in W boxes where the sealed back meant the only way out for heat was through the dome...

I just finished reconing that K-140 last year! (Note to self, do NOT use Duct tape to protect a gap for 25 years...) I put a 2225 coil, 2226 cone & spider in it to test an idea I had about increasing the Xmax, currently in a W box taking all the punishment I can throw at it...

The other one is still original, and paired with a reconed D-140...

Mike Scott in SJ, CA

Actually back in the 70's GAUSS speakers were "built" in many configurations like your idea...the best solution, is a lot of speakers and no more that 15-20 watts to power them...use the cube relationship...re: add one speaker to one speaker and gain 3-6 dB without any more power in to the system...add two more and get the same increase in gain...still no more power in...It used to be, in building high output sound systems the SPEAKERS were cheaper than WATTS...Things change but the physics doesn't...I go with a lot of high quality speakers and keep the power to each one relatively low...save on the re-cone costs...BIG TIME...

But keep experimenting...mix and match...you can optimize for your needs..."old school" never goes away...

[Gerry D]

I believe the K series introduced Kapton coil formers and epoxy adhesives to allow higher power handling. JBL never published T/S parameters for the "F" series to my knowledge. They were long out of production by the time that JBL adopted T/S design.

The T-S specs are available...they are the same as the "K" series. It seems the only real change was to the power handling capability of the speakers...I think I got the info from a Thiele Small data base...GOOGLE Thiele Small and you will find it as the first or second entry...although the data base in not complete there is a lot of useful info there...

[whitebeard]

Anyone know what years the K 120-16 was produced?

[gibber]

Actually my re-cone guy tells me they used NOMAX for the "K" series and KAPTON for the "E" series...kind of took me by surprise...

I can confirm Nomex on a K145, s/n 17464 and a later-series K145-16, s/n 10489

Anyone know what years the K 120-16 was produced?

K120-16 is the later series iteration of K120.
1979 thru 1982 to the best my memory. But others here in this forum (even this thread) would know with much more certainty


Now here's a trivia question on the Fender series (they are before my "active" time). When were the orange frame D...F sereis produced for Fender and were they orange for the whole Fender range within the D series or just D140F? The standard Fender-labelled D series just has the rear badge in orange. This pair fetched quite a decent price. Attachment 56992

[gibber]

This resurects a really old thread. However, I just found out what the "R" stands for - Rogers Instruments. Widget was on the right track. They are a well know organ manufacturer that is still in business. JBL developed a dedicated 15" driver for their use as an organ loudspeaker. Current staff at JBL believe that the D140R preceded the D140F, but I am not certain of this. I remember Harvey Gerst stating that he came up with the 140 model number for the 15" version of his "F" seires because 150 had already been taken by the 150-4 series. Maybe Harvey can clear this up.

Well, this answers a really old post that way back then resurrected a really old thread

There seems to be a bit of info on D140R here and there on this forum and the driver has been rightly compared to 2216 / LE15B in one post, as i just found out measuring two D140R's with different cone colors. One has a grey frame as in the eBay pictures posted elsewhere in this thread, i.e. there's a rounded recess near the screw holes on the front perimeter of the frame. The other frame's also grey but doesn't have this.

Confirming what Harvey Gerst assumed, namely the design was changed at some point, I got two speaker/PR15 passive radiator pairs and they copy the change in cone color and show a change in suspension. One has an all-paper 31044 cone/suspension whereas the other (21513, the one with the recesses) has not. Color might be due to UV(??).




But the real info: D140R seems very different from D140F in one respect (at least mine are). Fs on the two units here measures 21.6 and 22.5 Hz, respectively. Qts is .23 and .255 -- unchanged from D140F (but maybe would drop if the magnets were re-charged). So the "Rogers" version at least differs from the "Fender" version by having the 2216-style resonance.

LE15A/B, 2215, 2216, K145 all lack ventilation through the pole piece. Some quote this to be the reason for 150-4C's allegedly superior sound when compared to K145.

I have neither 150-4C nor LE15B/2216, so i can't compare the sound of 2216 to D140R or K145 to 150-4C, but it would be an interesting shootout between the same cone on either the nice giant magnet / underhung coil or with the also nice-to-have pole ventilation.
Maybe something for a future contributor resurrecting an old thread...

Ralph

[JBLBob]

I believe the K series introduced Kapton coil formers and epoxy adhesives to allow higher power handling. JBL never published T/S parameters for the "F" series to my knowledge. They were long out of production by the time that JBL adopted T/S design.

From what I understand, the K series was suppose to be the "new and improved D series. First off, the VC gap was a little wider. This was to cure the problem of VC pinch that sometimes happened with the old D series when they got hot. Second, the K series had cloth surrounds instead of paper. Third, the aforementioned changes allowed the speaker to handle more power...rated at 125W RMS. As far as the K's having a Kapton coil former, I'm not sure if and/or when that happened. I've reconed a number of K 120's and the original; cones had the aluminum coil former. Some guitarist tell me that the tone of the D's was better, but since I'm a keyboard player I can't comment on that.