Cabinet for JBL K-Series (....or D-Series)

[Dr.db]

Hey,


Im the prowd owner of a pair JBL K-120 and K-140.

Im very keen to build these ones some nice enclosures, but I have no clue of the recommended volume these drivers should get.

They are supposed to run at home, so no big PA-abuse....



And as well Im very unshure bout the type of enclosure; Sealed, Vented or even a Horn!?
What does work the best in bout ~20m² at home?







Thanks a lot for your help, I really do aprecciate it!!

Best wishes from Germany,
Olaf



Ps.
A different question; whats the difference between the "K" and the "D" Series?

[clmrt]

I found this -

http://www.jblpro.com/pub/manuals/enclgde.pdf

[Dr.db]

Hi,


thanks a lot for this link.



But they just mention the "E-Series" in this file.....

Are they exactly comparable with the K's?



(They suggest ~120liters für the 15" and bout 45liters for the 12"....)
I had the K-140 running in 110liters and the K-120 in 50liters....

Both speakers didn't seem lucky bout this size of enclosure's..... it somehow feld as if they need at least double that size.



Has anyone made on experience?

Best wishes,
Olaf

[Zilch]

They're not exactly the same, but close enough you wouldn't likely hear a difference. K Series is alnico, as I recall.

They're musical instrument loudspeakers, and not well suited for home HiFi use as woofers. They won't produce extended low frequencies except in extreme alignments with limited power-handling.

Put them in bass horns, if you'd like to try that. No extended bass there, either, but, well, fun.... :thmbsup:

[Dr.db]

Hi,

wouldn't the Alnico-Versions sound way better than the later E-Series?



How low do K-120 or K-140 really go?


Is the K-120, for example, producing music down to ~100hz without soundpressure loss?
Or is it allready getting less loud at bout 200hz!?
(....in which enclosure?)



How about the K-140?






Maybe I should rethink my ideas....

Which JBL Alnico Woofers do have great low bass response?






Well thank you guys a lot so far!! Im happy to get more tips and hints from yous.

Best wishes,
Olaf

[clmrt]

I was reminded recently of these documents, to be found in the library here.

http://www.lansingheritage.org/images/jbl/plans/1975-kit-plans/1975-porting.gif

[ratitifb]

I can't find the active link so here is pdf :)

[Dr.db]

Hey,

thanks for the links!!


I believe I should consider a different Chassi for the bottom end....

Which JBL Alnico Woofers do have great low bass response?
(....in which enclosure....!?)




Thank you a lot!
Olaf

[jcrobso]

They will work in bass reflex or as bass horn divers. They are excellent low bass speakers. John

[Doc Mark]

Hello, Dr.db,

Many years ago, I used a pair of JBL K120's as woofers in some hi-fi cabinets I'd bought. The original woofers had tiny "slug" magnets, and NO bass, at all! Whilst the K120's sounded FAR better than the original crappy woofers, they did not give me as much bass as I'd hoped, even though the boxes were about 1.5-2 cubic feet of volume. However, I could have done fine with the bass they DID offer, but in the end could not stand the massive ear fatique I got listening to them as hi-fi speakers! Now, I know more than I did back then, and could probably EQ some peaks out of their response. Also, they were used full range, along with a JBL 2105 midrange, and Peerless tweeter (which was so much less efficient, it might well not have even been there!!). If you need more info on building a box for the K120's, or the K140's, I can dig out my old JBL Enclosure Design kit, and send you the info that's contained therein. Let me know what box size you wish to use, and I'll send that info to you, including porting instructions. But, I'd suggest using the K120's for something else, though the K140's "might" give you what you are seeking. For what it's worth.... Take care, and God Bless!

Every Good Wish,
Doc

[jcrobso]

I know they sounded better than whatever the original speakers were.

Since I stopped playing bass in bands 40 years ago I have used my D140F for bass Hi Fi speakers. JBL doesn't list FS for the D140F, but the K140 has a FS of 30Hz. A box of 4~6 cubic ft. would be a good place to start.
There are many books and PC programs the will give you dimensions and port size if put the Thiele-Small info. John

[short_circutz]

My dad's been using various renditions of the "140" and has normally used them in 6 ft3 boxes.

[speakerdave]

Maybe I should rethink my ideas....
[B]
Which JBL Alnico Woofers do have great low bass response?



Alnico JBL woofers with better low bass response than K140 in a given sized enclosure: LE15A (Alnico, underhung), or 2231A/136A with original cones or any of the D130, 136A, 2231A, 2135, family of Alnico frames with 2235H recone kits in them. LE15A's are also reconable at about $200-250 per. Alnico woofers with mysterious histories should be magnetically recharged.

Also should mention the nearly ubiquitous Alnico LE14A, which will be the cheapest, though it usually needs to be refoamed.

You also might consider the neodymium JBL 1400nd, of which there is a pair currently on ebay starting at $825. They have dual underhung voice coils plus a braking coil. That would be the best next to the current HTF* Alnico 1500Al.

Then there are TAD Alnico woofers, which can be found fairly often recently on ebay in various states of useability, for $400-800 per pair. Reconing them is about $250 each, I think.

*HTF: Hard To Find

[Earl K]

- Acccording to JBLs' published TS specs, a resourceful reconer could turn a "healthy" K140 into quite a respectable hifi woofer ( the woofer must have the K140 kit in it, as well as still being in spec. at Fs [ or close to the original 30 hz figure ] ) . The net result would be a woofer that's a blend of the 2231a and the TAD 1601 . ( FWIW, exclude the shorter coiled E140 from this discussion . )

- The process involves replacing the aluminum dust cap with a paper type, as well as mass loading the cone ( @ 20 to 30 grams ) . Since I like the damping effects of aquaplas , I'd likely start with a 50 / 50 division ( of added cone weight ) resulting from an aquaplas coating and the use of a home built mass ring ( non- ferric type, riding on top of the voice coil ) .

- Obviously this sort of custom work needs to be done by a professional reconer who is also able to measure the resulting shift in TS parameters ( ie ; this is not something that the casual DIYer will want to attempt ) .

<> cheers

[ivica]

They're not exactly the same, but close enough you wouldn't likely hear a difference. K Series is alnico, as I recall.

They're musical instrument loudspeakers, and not well suited for home HiFi use as woofers. They won't produce extended low frequencies except in extreme alignments with limited power-handling.

Put them in bass horns, if you'd like to try that. No extended bass there, either, but, well, fun.... :thmbsup:

What is your oppinion about using K120 as Mid-bass speaker (say from 300Hz to 3000Hz)
Ivica

[jcrobso]

I get good bass down to 28hz below that nothing, since the horn has cut off.
I used the D140F because that is all I had at the time.
I did try some 2220H in the "K" horn, but went back to the D140F because of the higher sensitivity of the D140F.