Celestion BX15-2560

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So I've been offered this unit in an old Altec Lansing enclosure for about $80. I know practically nothing about it myself, and I can't find much online, either. I have the parameters, though (I don't know how to read them - only plot them into calculators):

--Driver Parameters--
Fs = 45, Hz
Qms = 7,517
Vas = 188, liters
Xmax = 2, mm
Sd = 850, sq.cm
Qes = 0,419
Re = 5,61 ohms
Le = 0,88 mH
Z = 8, ohms
Pe = 250, watts

Qts (calculated) ~ 0,398
Sensitivity (read in WinISD) ~98db/1w/1m

I'm looking for a sub/low-end for parties (and maybe festivals at some point) to accompany a pair of old 15-inches, which don't go very low at all. It is mainly to be used outside.

Coupe of questions:

1. Is this unit even meant for PA, or is it for a guitar amplifier? What consequences would this have?
2. Since it's already in a box, how important is the volume, if the port(s) are tuned to the right frequency?
3. Irrelevant question: Which frequency is the bass that kicks you in the stomach at night clubs and so on?
EDIT: 4. Does anybody know this unit? Is there anything I should be aware of, when buying it second hand?

Thanks in advance! :)
 
while i do not know the driver first hand, i did model it. based upon those simulations i'm fairly confident this is a midrange/guitar driver. a single driver high passed at 150hz-200hz is capable of some pretty respectable output (based on the simulations of course)
however, i don't think this is the driver you are after for the needs/wants you described above.
 
Damn it. :) Thank you for the replies! What region does xmax have to be in for it to be suited for bass?

xmax isn't the only parameter that determines a driver's suitability for low frequency reproduction. this comes from a combination of all driver parameters.
IME though anything with less than 8mm-ish of excursion just cant cover the lower frequencies well.
 
xmax isn't the only parameter that determines a driver's suitability for low frequency reproduction. this comes from a combination of all driver parameters.
IME though anything with less than 8mm-ish of excursion just cant cover the lower frequencies well.

Alright. :) Thank you!

So how would you determine a unit with limited T/S such as this:

Fs 38
Qms 5.14
Qes 0.36
Qt 0.336
VAS 6.99
No 2.7
Cms 1.12
Mms 156.8
Bl 26.98
RMS 250

It's a vintage Richard Allan Atlas 18 PA speaker I've had my eye on, too. But I have no idea what to do with just those parameters.
 
well i would simulate it. which i did ever so briefly. depending what your requirements are as far as spl and extension, the driver simulates ok. i'd suspect 5mm-ish to be the cutoff for excursion so the vented alignments would benefit from a high pass to protect them.

blue - approx 2.5 ft^3 sealed
red - approx 2.5 ft^3 ported tuned to 38
purple/pink - "maximally flat" ported
yellow - "extended bass" model

not a home theater monster by any means but should provide fairly decent results (within reason) for "standard" music
 

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Thanks a lot for your reply. :) New questions keep appearing ... I hope I'm not too tiring!

"... so the vented alignments would benefit from a high pass to protect them."

I'm not entirely sure, what you mean by that. If I go with a ported enclosure, I should run the woofer with a high pass filter?

Also: How important is box volume? You're going with ~70 litres. Can I use an existing box with say ~120 litres (example) and tune the ports/vents to match the unit still?

EDIT: I've been trying to plot the Atlas 18 into WinISD, but I don't know what to fill into the missing parameters. :-/
 
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depending on the type of material you play, a high pass filter could/should be used to protect the driver from overexcursion. excursion rises rapidly below port tuning, with the above speaker this is in the 40hz range. if you listen to edm, or even some popular rap/hip hop, there is content below that range.

box volume, as with most things design related is a compromise of what you are trying to achieve. ill keep away from too many broad generalizations and suggest simulating the driver in various configurations. ultimately you may find the compromise that suits your needs/wants. in the example you gave though, the 120liter enclosure loses a bit "up top" in the 80-120hz range but gains a db or so in the lower octaves. you also pick up almost 2 cubic feet of box.
enter compromise. is the dB of low end worth almost doubling the size of the enclosure?


most of the missing parameters can be calculated from the info given. here you go:
 

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Awesome. Thank you so much!

The reason for the different enclosure volume is that I've one lying around, which I was wondering if could be used, if the ports were tuned to the correct frequency. :)

I still can't WinISD to project properly. This spike keeps appearing whenever I raise the box volume above ~5 litres.
 

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Depends on your music.

What's your budget for drivers? - You already have a 120L cabinet. Some vintage drivers can be very expensive, and most perform poorly compared to modern subwoofers. Fine at a couple of watts, but if you hit them with much power, they'll quickly run into lots of distortion.

Chris
 
Well. I'll be listening to almost everything, except hiphop and that sort. So old rock, pop, modern dance (night club music), some dub, old techno. It's mainly for a small "garden party" I throw each year with ~50 people.

Well. I'm aiming to do it as cheap as possible. :) The Richard Allan Atlas 18 is just $70, and I've read in other threads here on the site, that it was a fair unit and still is. I'm probs not going to run it with big amplifiers, so it not handling a lot of power well shouldn't be a problem. :)
I've been looking at some "cheap" subs for sale as well such as Omnitronic, Behringer and the like that go for about $100, but reading the reviews, I kind of lose interest in them. I also like the vintage and diy.
 
So I've decided to go for the RA18 unit. I have some doubts about the box volume and tuning frequency.
Is a -2db drop a lot at around 60-80hz? See attached image.

Which of these two box sizes is ideal, when I already have a pair of 15'ers as "tops", which should (hopefully) cover the 60-20k hz area?

Basically; when is a drop too big?
 

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