thanks,
george

• http://www.eminence.com/Media/Speakers/Kappa/KAPPApic.gif

cheers,
george

If you skimp on the box volume, you will be dissapointed in the deep bass response. However, I have two 18A's, 16 cuft ABC boxes. They play really deep and they sound surprisingly nice. They don't have a lot of mechanical power handling, though. I have bottomed them out on normal music with a 100 watt amplifier. But they do get extremely loud in the process!

I can't call them my ideal choice for a home sub... But they're good.

I'll give you both in their enclosures (covered of course) for $750 :D

Adam

Where are you planning on positioning your sub in relation to your JBL's? Are you planning to put it in the corner, or are you going with multiple subs placed under or beside the 4655's? If you must go with Eminence drivers, here's what I'd recommend:

Eminence Kappa 15LFA (Adam is very familiar with these).
5.33 cubic feet tuned to 33 Hz will give a nice gradual roll-off with nice extension and relatively deep bass. Remember, this is a high-efficiency driver, so you can't expect sub-20Hz bass out of it.

Eminence Delta 12LFA
A 3.2 cubic foot box tuned to 38 Hz will give a pretty decent -3dB point of around 37 Hz. With room gain, you could probably expect good bass down into the low 20's range. Get two or more of these woofers and you'll have some excellent SPL.

I seem to remember reading Wayne's comments somewhere saying that Pi-Align is NOT really intended for subwoofer design. I feel the same way. Because a true subwoofer is really only intended to cover the bottom octave or two, the rules for successful design are quite different than for a full-range system. Generally speaking, deep bass SPL is easier to obtain from lower efficiency, low-resonance, high-excursion drivers used in multiples and/or with LOTS of power. The LF and LFA drivers in each Eminence range are a good compromise between high-efficiency and low resonance. I think the Delta's and Kappa's are the most user-friendly.

Good Luck!
Colin

on top of all this i just received a sample eminence driver(oem) available at a surplus price. take a look at the spec's and see if this is workable as a sub.

18" subwoofer
accordian cloth surround
3" kapton voice coil-4 layer
95oz ceramic magnet
Re(ohms) 7.84 Fs(hz) 22.74
Le (mh) 1.88 Mms(g) 145.3
Qm 10.30 Cms(mm/N) .3372
Qe .310 Rms(Ns/m) 2.0156
QT .300 Vas (L) 615.56
Xmax(mm) 4.80 Sd (cm^2) 1140.09
BL (Tm) 22.92 EBP 73.40
EFF(%) 2.25 SPL (db) 95.50

let me guess, these 18" drivers need a huge enclosure?

thanks for all your help.

cheers,
george

The Kappa 18A will operate in even a 5 cuft ported box. You could also run it sealed. However, we're talking limited extension.

Mine run in 16 cuft boxes tuned to something I do not remember. The f3 is about 25 Hz, though. You can definitely tell.

You could probably get similar results in a 12 cuft ported box. I'll run some simulations for you if you want.

Adam

I wouldn't worry about the dip you see in the published response curve of the Kappa 15LF. Eminence does not typically measure their drivers in an appropriate enclosure under real world conditions as I'm sure Wayne can also attest. I can recall reading in more than one article (I can't remember the sources right now) that one shouldn't take the published response graph of ANY woofer very seriously in the range below 200 Hz. The reason being for this is that under the test conditions, more often than not there are response nulls caused by the measuring room and equipment itself. Its nearly impossible to get a truely accurate picture of a woofer's capability for deep bass response from a manufacturer's published response graph. All these graphs are really good for is to show what happens at the TOP of the woofer's useable range where it will generally start to "break up" and distort. You might remember that for a brief time, I was seriously considering using the Kappa 15LFA instead of a Delta 15 for a modified set of Theatre Four Pi's. I changed my mind when I saw that the Delta 15 has some nasty peaks in the frequency response above 1.6K. It really should be crossed over below 1K, which means it wouldn't mate well with the Eminence PSD2002.

So yes, I stand by my recommendation for the Kappa 15LFA for subwoofer duty.

Colin

I'm sure it was just a "slip of the tongue," but I felt the need to point this out so the Theater four π and Delta 15 owners don't have a panic attack.

I think what you meant to say was the follwing:

You might remember that for a brief time, I was seriously considering using the Kappa 15LF instead of a Delta 15 for a modified set of Theatre Four Pi's. I changed my mind when I saw that the Kappa 15LF has some nasty peaks in the frequency response above 1.6K. It really should be crossed over below 1K, which means it wouldn't mate well with the Eminence PSD2002.

Response curve of Eminence Delta 15

Just thought I'd point that our, for clarity's sake.

Wayne