Hi Charles,

K 140 should work fine in 4560 cab, except for a note from JBL about longer excursion capability of some drivers (like K 140) when used in 4560 type box: risk of cone striking horn throat if you are too ambitious with low bass level. Other than that mention I don't really see a problem.

Be aware though JBL mentions these low frequency horns are designed for long throw, therefore ideal for large halls, outside environment or similar other applications. Not really for typical home use.

JBL does specify the following drivers may be used with 4560: 2220, 2205, E 140 or E 145. Personnaly, I tend to think its somewhat "wasting" nicer 2205 and E 145 in a 4560 in view of the huge increase in response (100 hz - 1000 hz or so, not real bass there) caused by the front loading horn, but that's another matter.

From JBL's TS parameters table for drivers: K 140 Fs 30 hz, Qts 0.21, Vas 297 L.; E 140 Fs 32 hz, Qts 0.17, Vas 297 L.; 2220H 37 hz, Qts 0.17, Vas 297 L. The latter is the "ideal" purposely designed woofer for 4560 use, though others will work fine with some differences. The reason being so is the closeness of their basic TS parameters seen above.

E 140 is basically an updated K 140, with ferrite type magnet and other minor changes.

Naturally, if you don't have room for 4530 then you won't have room for larger 4520 or 4550 either. Those four horn-loaded boxes are what JBL had to offer in Pro gear.

Another and better option in my view is to build a vented-box with that driver, JBL provided some useful info about this. The recommended vented-box volume for E 140 (and incidentally K 140) is 3 -8 cu.ft. (85 - 225 litres). I wouldn't go towards the upper volume range as driver will show, response wise, signs of being stretched considering its low Qts. I'd stay more in the lower part of the range.

In its Enclosure Guide for example, JBL suggests for E 140 and others (and incidentally K 140) a 4 cu.ft box (113 litres) tuned at 40 hz, which makes more sense to me than 7-8 cu.ft in view again of driver low Qts.

I use my own 2205H in vented-box bass cabinets with flat alignment (not subwoofers) and I like the results even if not fashionable by today's standards. Bass is tight, fast and dynamic. When space is a constraint going vented-box is the best compromise in my view.

According to Bullock, low Qts drivers and flat alignments have better transient response. I tend to agree with that in my case. Could be an explanation why I like the sound of the 2205H so much and kept them for 37 years or so now, even though its a Sound Reinforcement driver... Regards,

Richard

P.S. If you need the info re 4560, JBL's Musical Instrument drivers in vented boxes and Enclosure Guide let me know. I also have a Manufacturer's Plan for a 4560 type of box from another Company than JBL which may be useful. You can send me a Private Message here if you like with an e-mail address so I can forward the info to you.