I have always laid my speak on it back, with the cone facing upwards. I put a ball of lint on the cone, or even a little bit of salt. Then, using the sine wave generator, sweep through the frequencies until I it seems to cone is not moving (as indicated by the lint/salt no longer vibrating). But this seems to leave about a 5 Hz window, not the exact Fb frequency. Thanks for the candle technique tip - I will give it a try next time and see if it is more accurate.
Okay, pretty much the only 15 I've found that works well in the 190 litre cab is the Kappalite 3015LF, giving massive 98.5dB sensitivity. I've had simulations of up to a flat 99.5dB sensitivity but only from a reduced Mmd version of the B&C 18TBX100.
I have a 130L bass reflex cab simulation that the design works well in, but of course it will be less sensitive. The limitation of bass reflex is only being able to increase the sensitivity at the tuning frequency.
I have a more sensitive rear loaded/tapped bandpass horn (or scoop) simulation that it works well with. I haven't worked out how to fold it up yet. Bass reflex boxes are easy to build what you modelled! I originally used the 3015lf, then x the numbers by 13/19 (ratio of good bass reflex cab sizes).
This was only a hornresp graph, but I got similar and consistent results with many woofers, and I found I got a more Simplexx - like drooping curve if I made the cab too small. You probably gain a bit higher voltage limit on the Simplexx, but I don't know much about them or have the plans.
Interestingly, 9 HL10 woofers sim well in the cab if you could fit them in or could be bothered to spend the money. There seems to be a 'driver equivalence' dependent on Fs and QTS. Where 1 x 3015LF ~ 2 x 3012LF ~ 4 x BP102 (I think judging from BFM cabs) ~ 9 x HL10 where response in the same cab is concerned.
The Timplexx 15 and DJ's Dream are the exact same cab (post 2018). I have a 'Timplexx 12' (unpopular on the BFM build thread!) that runs 3dB less sensitive (like the JBL curve only going to 40Hz). I can confirm solid output to the 38Hz HP on just 15 Volts when corner loaded in my flat (detached of course!). I can see my ball lamp shades move, can't wait to try 40 Volts! It also models well with the Faital Pro 15HP1060 giving 80 Volts!
Probably slightly better than a Tuba 18 or Autotuba, considering it uses an 8 ohm (though way more expensive) driver. There's an impedance rise in both cabs so that's why I've excluded horn impedance. In fact it seems MORE pronounced in bass reflex, albeit a lower minimum at tuning.
If you had to choose which was "better" for an SS15 - the Kappa 15LF (steel frame) or the Kappa P15LF2? Input 50V or less - for extension-cord-run-limited use. I have a couple spare LF2's, and I'm ordering some of the steel frame drivers for an unrelated hi-fi project. At 15% off right now, I could sneak in a couple extras and no one would notice.
After simulating I see that the W750 from 18 Sound actually doesnt look bad in the SS15. So I have to build one now. Thanks another project added to the list. 
I was selling them because they had been sitting in my shed. Now that the SS horn can use them I look forward to building one and seeing how I like it.
I was selling them because they had been sitting in my shed. Now that the SS horn can use them I look forward to building one and seeing how I like it.
Has anyone tried this yet? 99dB, 12mm xmax, Qts 0.4....
http://prvaudio.com/pdf/15SW2000-4_Datasheet.pdf
Tim, faital pro 15 1030 hp, 205 liters, folded, and built. 98.5db sensitivity down to about 43 hz.
http://www.diyaudio.com/forums/subwoofers/254752-oth40c-15-loaded-compact-th-flat-40hz.html
Rigidity
I'm very new to this site and learning a ton. Looking at building one of this just out of pure curiosity
Just a quick question when it comes to the rigidity of the box while clamping the prices together why not drill holes and insert small dowels from the horn to the sides in order to help with that. Also what kind of amplifier would you use to keep this for maybe home theater use or testing in different situations it would be standalone with just signal inputs?
I'm very new to this site and learning a ton. Looking at building one of this just out of pure curiosity
Just a quick question when it comes to the rigidity of the box while clamping the prices together why not drill holes and insert small dowels from the horn to the sides in order to help with that. Also what kind of amplifier would you use to keep this for maybe home theater use or testing in different situations it would be standalone with just signal inputs?
Yeah the dowels thing was actually mentioned a couple of times in this thread. I think people were calling it broomstick bracing or something.
You mentioned you're interested in home theater. I'd actually probably steer you away from this design if home theater is your only goal. Subs for home theater use ideally go very low. Appreciable output down to 25hz or lower is ideal and not that hard to get if you're designing for that from the start.
The SS15 design is targeting live sound reinforcement. These are made to be very loud in a reasonably small box but it does that by sacrificing low end output. The response starts dropping like a rock at 55hz. By the time you're hitting 40-35, you're getting almost nothing out of it. That means you won't be hearing those room rattling earthquake-like rumbles out of movie sound effects.
If home theater is what you're looking for, I've heard good things about Bill Fitzmaurice's Tuba HT design. Another option is the tapped horn described here: Tapped Horns
You mentioned you're interested in home theater. I'd actually probably steer you away from this design if home theater is your only goal. Subs for home theater use ideally go very low. Appreciable output down to 25hz or lower is ideal and not that hard to get if you're designing for that from the start.
The SS15 design is targeting live sound reinforcement. These are made to be very loud in a reasonably small box but it does that by sacrificing low end output. The response starts dropping like a rock at 55hz. By the time you're hitting 40-35, you're getting almost nothing out of it. That means you won't be hearing those room rattling earthquake-like rumbles out of movie sound effects.
If home theater is what you're looking for, I've heard good things about Bill Fitzmaurice's Tuba HT design. Another option is the tapped horn described here: Tapped Horns
It doesn't seem like the SS15 goes all that low.... what's the lower limit of the design? I thought it did more at 40Hz than that. It seems to have a similar response to a simulaion of a 6th order bandpass with 1 chamber at 140-150L, and 51Hz and the other chamber at about 45L and 110Hz (3015lf woofer parameters used)
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Also if anyone in the US wants to cheat with regards to driver costs, how about a design with multiple MCM 55-2421 woofers? You could probably fulfil all the requirements of the challenge with either a 40Hz TH, a BR or a 6th order bandpass.
In UK or Aus, you're more limited with bang for buck.
In UK or Aus, you're more limited with bang for buck.
How about this version, where did it all end up?
Seems smarter having both cone correction, longer path and no "dead air"
Seems smarter having both cone correction, longer path and no "dead air"
There is definitely a price to pay, but I think I have found one of the best deals for it in the area. Wood is generally pricey around here, and I managed to get 2 sheets for 127€, precision cut to less than 1mm accuracy. I'm sure it's more than north americans pay, but I have neither the facility for accurate straight cuts, nor the ability to transport full sheets of wood (small car!).
Hey Jim, I'm having some trouble reading your measurements describing what distances from the edges the boards are to be placed. I've played around with a sketchup model, trying to get the most linear possible expansion, but I have to say my results look quite different from yours.
DISCLAIMER FOR ANYONE BROWSING THIS THREAD: THIS IS NOT THE OFFICIAL JBELL LAYOUT
As you can see, my path divider coming from the top of the horn is perpendicular to the top, and not angled like yours. However observing the cross sections, this seems to yield a good expansion on paper. It would be great if you could write your measurements more legibly for me
Still waiting for my Delivery of Eminences....
Oh and one more thing: what's this threads opinion on a good finish. Speaker felt, or some kind of robust paint? I already have edge rails and corner protectors on the way.
Rat Fur (carpet) is expensive, heavy, and gross when it gets dirty or wet.
I just use black paint, and carry a bottle of black shoe dye to touch up scratches.
I have friends that prefer the rat fur, if you do that buy a dark grey color.
Light gray looks OK when new, but shows any dirt after a while.
I just use black paint, and carry a bottle of black shoe dye to touch up scratches.
I have friends that prefer the rat fur, if you do that buy a dark grey color.
Light gray looks OK when new, but shows any dirt after a while.
I think you might have found the wrong thread because I'm struggling to find context for your comment, but while we're here I'll always be a huge advocate of duratex. I've painted 11 big cabs so far. It seems crazy expensive for a gallon of paint, but the coverage is fantastic and the durability is extremely good. You can paint a surprising number of cabs with a gallon.
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