Assuming you have figured cabinet volume correctly, it should be close if you have the 42 Fs drivers instead of the 43.65 Fs drivers.
I was wondering why it looked better than the sims I posted yesterday, then today remembered there are two versions of the 3015LF.
I like Djim's tapered plenum.
Built about 6 tons of cabinets with tapered plenums, they work well.
Art
Three solutions for you Oliver; quality eq , lower its crossover point, use RCF principles from the ESW1015 (or the original ESW1018 concept if you like but both will need extra volume), or even better use a combination and that's beside the fact that the peak will be less if every second cab is put upside down, and therefore the cube form comes in handy 
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I remember seeing a post somewhere, directing to the 2 different stampings on the back of the cones to verify what versions one had. I don't remember where that post is tho.
You will find out what you have when you test the cabinet :^).
Experimenting with Fb is fun, the sims don't tell you everything.
Don’t let the fun turn into frustration, it’s not worth. Just look to what you have accomplished so far (no, didn’t mean that sarcastic this time). You seem to dig into all details just because you cannot accept data without understanding, nothing wrong with that. Maybe it’s just time to build something, even if it is made from cheap chipboard. Just get the adrenaline rush from your first build: cutting wood, smelling glue & dust and getting thrilled by its first sound (even it’s not perfect). It will empty your head!
That is why you should build it and experiment with the port length, you can decide which works best for the music you like.
The box will work with a wide range of Fb, and with the 4" wide port you can experiment all the way from a too high Fb (no duct) to way too low, which will act like a sealed cabinet.
None are "wrong", none are "right" (though one Fb will result in the flattest response in a given box volume), the varying alignments are a continuum.
If you want to add to your indecision, consider making a push pull Keystone tapped horn enclosure, slightly larger size (would need to be about 32.5 wide) than your present box idea, but will be about 6 dB louder.
Art
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Hi Djim,
I'm not getting frustrated
I just can't decide whether to build somethin with these 2 new 3015LF's or to sell them and go with a 30 Hz TH (with a higher quality driver - less pwr compression, etc) I've been eyeballing. I'm working on low funds at the moment, so I'm trying to be careful w/my decisions.The PPSL I posted was a 37 Hz cab and I don't know if they'd be ideal for PA, but according to the sim it would be 3-5dB louder @ 30 Hz than the 2 SS15's I have. I know what you mean though - I could've built one by now 
and got it out of my system. Do BR6 enclosures raise the low corner when stacked (unlike TH's)?
Hi Art,
I'd love to. Do you have any pics, plots, design ideas, etc for an enclosure? I've seen your Keystone thread, but didn't see any design models. Maybe I missed it..??
Hi Crescendo, just build some cabs for the 3015LF’s and see how they work out. Afterwards you still can decide to sell them or not. Used or not, second handed is second handed, so would it matter for the value of your drivers?
Just don’t focus too much on the 30Hz output because 15 inch PA drivers are not built for that range. Roughly, the -3dB point for LF PA drivers (with a stiff suspension):
50/55Hz for 12inch
40/45Hz for 15inch
35/40Hz for 18inch
For so called extended LF drivers that would be approx 5 Hz lower. Although you can force them to play lower, it will be at cost of SPL and max power. In my view the 1/3WL of a TH should be on or above the Fs of the driver to get decent efficiency. Designing TH’s lower will roughly cost you 0.7dB for every Hertz.
If you are tight on the budget make sure your system at least delivers the efficiency needed in your case. Even if you can design a system with that extra octave lower, there is nothing more frustrating (and costly) as running out power/headroom. Also keep in mind you always can trick the minds of your audience by suggesting there is much more low end than there really is. A little eq or even better an extra filter + parallel compression of just the lower part of the sub range (40 to 60Hz for instance for JBell's SS15) gives more 'balls' than an extra half octave that is rolling off.
Just don’t focus too much on the 30Hz output because 15 inch PA drivers are not built for that range. Roughly, the -3dB point for LF PA drivers (with a stiff suspension):
50/55Hz for 12inch
40/45Hz for 15inch
35/40Hz for 18inch
For so called extended LF drivers that would be approx 5 Hz lower. Although you can force them to play lower, it will be at cost of SPL and max power. In my view the 1/3WL of a TH should be on or above the Fs of the driver to get decent efficiency. Designing TH’s lower will roughly cost you 0.7dB for every Hertz.
If you are tight on the budget make sure your system at least delivers the efficiency needed in your case. Even if you can design a system with that extra octave lower, there is nothing more frustrating (and costly) as running out power/headroom. Also keep in mind you always can trick the minds of your audience by suggesting there is much more low end than there really is. A little eq or even better an extra filter + parallel compression of just the lower part of the sub range (40 to 60Hz for instance for JBell's SS15) gives more 'balls' than an extra half octave that is rolling off.
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Hi Djim,
I guess since they are New In Box, I was thinking I could get an easier sale for more $ than if they were used.
Since I have upgraded my power amp recently, I do have a bit of headroom. But, with this PPSL, it requires +6dB of eq at the cut-off freq. 3015LF's are 450W rms/ea x2 drivers = 900w + 6dB = 3600W - so, my amp must be capable of 3600W, correct? That's 3dB more than the 3015LF's MAX pwr. Am I missing something?
Re: EQ & filters: I'm already crossing over my SS15's lower than many others since the filter begins to cut much higher than the set point. According to WinISD, I am still within xmax by doing so, even with some eq you recommended quite a while back in the SS15 thread The majority of my gigs are dubstep, so a lot of sweeping sine waves and I haven't heard any funny noises from the drivers (knock on wood) and they don't get very warm either. We're running 2 of them off 1 ch. of my PLX3402 (1100w/ch @ 4 ohms). On top of that, I am running a limiter (not too heavy) w/fast attack & release times.
I guess since they are New In Box, I was thinking I could get an easier sale for more $ than if they were used.
Since I have upgraded my power amp recently, I do have a bit of headroom. But, with this PPSL, it requires +6dB of eq at the cut-off freq. 3015LF's are 450W rms/ea x2 drivers = 900w + 6dB = 3600W - so, my amp must be capable of 3600W, correct? That's 3dB more than the 3015LF's MAX pwr. Am I missing something?
Re: EQ & filters: I'm already crossing over my SS15's lower than many others since the filter begins to cut much higher than the set point. According to WinISD, I am still within xmax by doing so, even with some eq you recommended quite a while back in the SS15 thread
The majority of my gigs are dubstep, so a lot of sweeping sine waves and I haven't heard any funny noises from the drivers (knock on wood) and they don't get very warm either. We're running 2 of them off 1 ch. of my PLX3402 (1100w/ch @ 4 ohms). On top of that, I am running a limiter (not too heavy) w/fast attack & release times.
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Hi Crescendo,
Yes, the SS15’s will lack efficiency in the low end needed for D&B, Dub(step) and some others. For that kind of music 18inches (or even bigger) are actually a must! Putting the 3015LF’s in a low tuned PPSL will give you a more flat response down low but you will miss the efficiency higher up. Indeed, don’t feed your 3015LF’s with 1800W per cab because it will kill them. Also it wouldn’t work in practice anyway because the last 1000 watts would almost get lost by power compression. So that’s not a realistic solution.
About parallel compression, that is something different from what you have done and will therefore sound very different. The trick of parallel compression is that you feed two signals to the sub amp; one directly signal from the crossover as normal, the other one trough another processing stage. That processing stage needs to be squeezed totally by a compressor and use the output gain on the compressor to mix the processed signal together with the 'untouched' signals into the sub amp. This way you can pump up the rms signal of the low end while keeping the peaks (dynamics) from the ‘untouched’ signal. It will make subs sound larger then life. To set out the filter frequency for the processing stage you can take the 3rd knee point in the response of the TH.
Yes, the SS15’s will lack efficiency in the low end needed for D&B, Dub(step) and some others. For that kind of music 18inches (or even bigger) are actually a must! Putting the 3015LF’s in a low tuned PPSL will give you a more flat response down low but you will miss the efficiency higher up. Indeed, don’t feed your 3015LF’s with 1800W per cab because it will kill them. Also it wouldn’t work in practice anyway because the last 1000 watts would almost get lost by power compression. So that’s not a realistic solution.
About parallel compression, that is something different from what you have done and will therefore sound very different. The trick of parallel compression is that you feed two signals to the sub amp; one directly signal from the crossover as normal, the other one trough another processing stage. That processing stage needs to be squeezed totally by a compressor and use the output gain on the compressor to mix the processed signal together with the 'untouched' signals into the sub amp. This way you can pump up the rms signal of the low end while keeping the peaks (dynamics) from the ‘untouched’ signal. It will make subs sound larger then life. To set out the filter frequency for the processing stage you can take the 3rd knee point in the response of the TH.
Hi Crescendo, parallel compression is not available in (any?) digital crossover systems. Also, using compression in digital crossovers means you compress the whole bandwidth of the sub (including the peaks/transients). So the end result is different from parallel compression. Compressing the whole signal (blue signal in the graph), like all digital crossovers do, will sound much more processed/unnatural and destroys the dynamics at higher compression levels. It will also lead to more suppression of the lowest part of the sub range since the attack of kicks triggers the compressor.
You can higher or lower the amount of the parallel compressed signal by using the output gain of the compressor.
You can higher or lower the amount of the parallel compressed signal by using the output gain of the compressor.
Yes, you missed the plans, they are in there.Hi Djim,
I'm not getting frustrated
Do BR6 enclosures raise the low corner when stacked (unlike TH's)?
Hi Art,
I'd love to. Do you have any pics, plots, design ideas, etc for an enclosure? I've seen your Keystone thread, but didn't see any design models. Maybe I missed it..??
A PP dual 15 could be made easily by widening the cabinet to fit them, and adding a standoff to the reversed cone adequate to account for the magnet depth.
compression ratios of the ppsl ??
Yep, Me again. Am trying a different plenum, much smaller this time, and wanted to ask if my calculations with respect to the compression ratios agree with how you figure yours (?) I'm using a 12 inch driver; the approx SD is about 90 square inches and my plenum exit is also 90 sq inches, so is that a 2:1 ? (or does the volume of said plenum come into play somehow?)
Thanks in advance that you (djk) or anyone else may offer.
Yep, Me again. Am trying a different plenum, much smaller this time, and wanted to ask if my calculations with respect to the compression ratios agree with how you figure yours (?) I'm using a 12 inch driver; the approx SD is about 90 square inches and my plenum exit is also 90 sq inches, so is that a 2:1 ? (or does the volume of said plenum come into play somehow?)
Thanks in advance that you (djk) or anyone else may offer.
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