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Old 17th December 2005, 12:12 PM   #1
Buhl is offline Buhl  Denmark
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Default JBL E140 suited for OB Uframe sub ??

Having read the Precision Devices thread with great interest, I became wondering about the set of JBL 15" woofers I have on my "spares shelf" would be suited for a U type open baffle frame ?

Its main parameters is:
Resonant Frequency (fs) 32 Hz
Impedance (Re) 5.5 ohms
Coil Inductance (Le) 1.1mH
Electromagnetic Q (Qes) .19
Mechanical Q (Qms) 5.0
Total Q (Qts) .17
Compliance Equivalent Vol. (Vas) 300 Liters/10.5cu. ft.
Voice Coil Overhang (Xmax) 3.5mm
Surface Area of Cone (Sd) .089 m2
Efficiency (Half Space) 4.9 %
Pe Maximum (Watts) 200
Displacement Volume (Vd) 312 cm3
Flux Density 1.35 T (13,500 gauss)

What do you think ?

Cheers !
Buhl
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Old 17th December 2005, 03:19 PM   #2
GM is offline GM  United States
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Greets!

With such a low Qts and fairly limited Xmax, it won't handle much power and be very rolled off beginning around 200 Hz if you don't use some form of EQ to flatten its rising response. Wood is cheap though, so why not try it and see if there's any room position that makes it an acceptable performer?

GM
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Old 18th December 2005, 06:09 AM   #3
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What kind of bandwith do you have in mind?

Do you have some eq that you can use, say a bit of parametric eq you can quickly dial in? For this to work as a quick "test and see" project you need some eq. Perhaps try a U frame first since this will need less eq for a given size, and you can get an F3 as low as 60 hz without being too big or using eq. You want this much bass at least to get a feel for how much you like it.

How many of them do you have?
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Old 19th December 2005, 09:50 AM   #4
Buhl is offline Buhl  Denmark
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Quote:
Originally posted by paulspencer
What kind of bandwith do you have in mind?

Do you have some eq that you can use, say a bit of parametric eq you can quickly dial in? For this to work as a quick "test and see" project you need some eq. Perhaps try a U frame first since this will need less eq for a given size, and you can get an F3 as low as 60 hz without being too big or using eq. You want this much bass at least to get a feel for how much you like it.

How many of them do you have?

I think that I have a unreasonable bandwith in mind - I was playing with the idea of the sub(s) playing with my proac 2.5 clone - that has "enough" bass, but is some what boomy and colored - I have a pair of Quad63, hence the idea of dipol bass.
I have a active electronic crossover, with mono sum, plenty of amp power, and a semi pro 15 band graphic eq to toy with. I have 12 dB at 20Hz and then 15 bands up, and then 12 db Master level, so if I reduce at 60 some Hz, and then boosts the master level, i can simulate a larger boost at the lowest level.
I have two JBLE140 - and I can se from hte data, that this is a "play loud" unit with limited Xmax, and I will thus run into excursion probs at high level. On the other hand, the two 140 i parallel should give about 100dB of sens, and my proac is down at 87dB so mabye it will be ok for testing of my liking of dipole bass.

Thanx for the replys !

Cheers !
Buhl
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