P.A. 18 TH (18tbw100 30x38x22.5")

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Ran a quick rough calculation and rough sims, here is what i came up with.

internal cabinet width 21"
external dimms 30"x38"x22.5"

driver is b&c 18tbw100

http://www.parts-express.com/pe/showdetl.cfm?partnumber=294-6008
$387 from P.E.
$352 shipped from savinglots.com
input screen
oxjk.jpg

and with 2.83V
gs5z.jpg


and with 900w
hei0.jpg


Same exact fold as the PAL12. Driver center (10" from s1) is moved up in the throat so it will physically fit in the cabinet. Other lengths shortened accordingly.
18mm Baltic birch recommended.
 
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just a sugestion

ID=28.00
Ang=2.0 x Pi
Eg=2.83
Rg=0.00
Fta=3.37
S1=546.00
S2=546.00
Con=0.10
F12=0.00
S2=546.00
S3=1031.00
Con=105.00
F23=0.00
S3=1031.00
S4=1644.00
Con=104.00
F34=0.00
S4=1644.00
S5=2000.00
Con=40.00
F45=0.00
Sd=1210.00
Bl=26.49
Cms=8.38E-05
Rms=6.78
Mmd=222.56
Le=2.45
Re=5.30
TH=1
Vrc=0.00
Lrc=0.00
Ap1=0.00
Lpt=0.00
Vtc=30000.00
Atc=1001.90
Pmax=100
Xmax=5.0
Comment=18tbw100

edit/ah yes i remember the topic now.
anyway you can try, it maybe a testbox .
looks like you can get a bit more in the 60-80 range
 
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seller TSG at Ebay has or had some custom Eminence 18 with claimed 5" coils and 160oz slug


TSG 18 inch Subwoofer 5 inch Voice Coil Free Shipping Any Reasonable Offers | eBay

TSG 18-250 18" Subwoofer
with 5 Inch (125 mm)Voice Coil
Call 801-771-1820 with any questions.
SPECIFICATION
Nominal Basket Diameter 18", 460mm
Nominal Impedance* 8 ohms
Power Rating
RMS Watts 800W
Music Program 1600W
Resonance 35Hz
Usable Frequency Range 34Hz-3.7kHz
Sensitivity*** 99 db
Magnet Weight 160 oz.
Gap Height
Voice Coil Diameter 5", 125 mm

THIELE & SMALL PARAMETERS
Resonant Frequency (fs) 35 Hz
DC Resistance (Re) 5.0 ohms
Inductance 3.0mh
Mechanical Q (Qms) 9.21
Electromagnetic Q (Qes) .29
Total Q (Qts) .28
Compliance Equivalent Volume (Vas) 249.4 liters / cu.ft.
Peak Diaphragm Displacement Volume (Vd) cc
Mechanical Compliance of Suspension (Cms) mm/N
BL Product (BL) 24.3 T-M
Diaphram Mass inc. Airload (Mms) 148 grams
Efficiency Bandwidth Product (EBP)
Maximum Linear Excursion (Xmax) mm
Surface Area of Cone (Sd) cm2
Maximum Mechanical Limit (Xlim) 12 mm

MOUNTING INFORMATION
Recommended Enclosure
Sealed
Vented
Overall Diameter
Baffle Hole Diameter
Front Sealing Gasket Fitted as standard
Rear Sealing Gasket Fitted as standard
Mounting Holes Diameter 0.28", 7.1mm
Mounting Holes B.C. D.
Depth
Net Weight 35.7 lbs.,
Shipping Weight 73.9 lbs.,

MATERIALS OF CONSTRUCTION
Coil Construction Aluminum voice coil
Coil Former Polyimide former
Magnet Composition Ferrite magnet
Core Details Vented core
Basket Materials Die-cast aluminum basket
Cone Composition Paper Cone
Cone Edge Composition Cloth cone edge
Dustcap Composition Solid composition paper dust cap
 
I agree that below 80hz it is quite flat. however, without actual 2.83v 1 meter measurement ithink its hard to say this is actually due to 'better results' when compared to the sim. while i agree you are only about -2/3db between your 40hz peak and your 60hz valley, its still about 6db down from its 95hz peak, which is more in line with the sim. this suggest to me that rather than 'gaining sensitivity' in the 50 to 70hz range, you've just lost a little bit of the low freq peak, which makes it appear flatter, but is a result of lost sensitivity.

This could also be a product of slight lf rolloff of the measurement mic i suppose, and initialy i thought this was one of the 30hz filter graphs, which would put it like 1.5db down at 40 hz but at second glance that doesnt seem to be the case
 
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I agree with this sentiment. but if the *flatness* of your measured response was a result in reduced sensitivity in the LF (without an equivalent decrease in displacement at those frequencies) then it means less overall peak output.

now, if cone excursion between 37and 45 decreased as well, then hell, you've gained flatter, and more peak output (although it will take more power to reach it) as tapped horns tend to exhibit peak excursion within their passband (with a hipass activated).

regardless, I'm liking where you are going. I may very well build a PAL12 (found a pair for 200 even), considering its a small amount of build materials, and low cost. It will be a good first tapped horn build. Thank you for posting your results, and your designs, I love reading of your work

please dont take my posts the wrong way. The only thing that irks me at all is the scale of REW, and thats not your doing lol.
 
changing scales on REW graphs

Is there any way you can adjust the scale on the REW measurments to match the scale of hornresp? i have no idea why REW rrpresents data on a 10db scale, cause that pretty much makes everything look 'flat'
.
The little plus and minus symbols in the upper left hand corner allow you to change the scales.
The ones in the right hand corner change the phase scales.
Also, the second from right dialog box labelled "Limits" above the screen will let you set the default scales.
You can also turn on the scroll bars to allow the traces to be moved up and down.
.
And, trying to get the graph to match one from HRSP requires that you resize one or the other, but it can sort of be done.

Hope this helps,
Dave
 
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Power requirements. How much power is needed with those 4 18" monsters to reach that level?

If I had lab gruppen amp with 9-14kw on tap, I wouldn't even bother with all the space tapped horns take up.

A pair of NU6000's would drive a pair of low-ish tuned 2x18's beyond xmax and cost about $900 including 4U case. But should each be on their own 15a or 20a breaker.

I would model that B&C woofer in a ported box targeting 20mm excursion (one way) on 1500w and see where that gets you for extension and output.
 
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so its your opinion the tbw100 is good to 20mm xmax? wow. that changes things for me a lot, as I was pretty much shoehorning myself into sw115 territory by being unwilling to let sims for the tbw go over 12 mm. (not trying to derail your thread mrgsr, but I'd say thats applicable for you too)
 
so its your opinion the tbw100 is good to 20mm xmax? wow. that changes things for me a lot, as I was pretty much shoehorning myself into sw115 territory by being unwilling to let sims for the tbw go over 12 mm. (not trying to derail your thread mrgsr, but I'd say thats applicable for you too)

Well, they are saying xmech is 28.5mm, so (IMHO), if you aren't super concerned about a bit of distortion when going full tilt, modeling to a target of 70% of xmech (28.5 x .7 = 20mm) & real world RMS amp output (1500w nominal) seems like a reasonable target, assuming you intend to set hard highpass and limiters to keep things from blowing up.

Granted, this is a "low tuned" (~30hz) design scenario where power is reasonably low. I don't think it would be a good idea to tune to 45hz and hit it with 3000w for 20mm excursion, would either burn it out or tear it apart.

My subs xmech at around 20-22mm, nominal xmax 12mm, and have seen plenty of action at the 14-16mm range on a maxed out nu6000 (amp tested 1500w rms, subs 800w rms nominal) without a problem.
 
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