"Best" PA subdesign for the Eminence Kappalite 3015LF

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If you find my thread on the 'stadium horns' that I built using 3015lf's, you'll find a real 30hz option... and several posts about the whole BFM mess. Stadium horns are anything but portable, and you can only drive them to 50v or so safely. The SS15 is the 'balanced' option between loud and low, that's really the best bet in my opinion.

I was compelled to look this up since I hadn't seen it. Looks pretty awesome and reasonable to build! 50% larger gross volume than a t48, correct?

http://www.diyaudio.com/forums/subw...s-merged-subwoofer-thread-13.html#post2605761
 
Hi Robin N Zone,

Post #17: "...
I´ve seen references to the Furysub, but all links to it have been dead..."

You'll find the furysub in this thread: http://www.diyaudio.com/forums/subwoofers/131852-live-sound-specific-tapped-horn-thread-54.html . I don't remember if the one in Post #536 was the last drawing, but it should be close enough. It's a good thread to read through.

As to the SS15, it's the best compromise I've seen for the 3015LF, a slight improvement could probably be had by incorporating cone correction into this design: http://www.diyaudio.com/forums/subwoofers/190635-th-18-flat-35hz-xoc1s-design-57.html , Post #562 and so on (I recommend this thread to anyone who is looking for an extended range PA TH). Maybe jbell has some aditional information.

Hornresp does not indicate the losses at high power levels, according to the experts that have actually build and measured both bass-reflex and tapped horn enclosures that is where the TH really shines. In other words, if you want to know you got to build both, and measure (preferably outdoors, @ 10 meters w/ 100W, e.g.: like Danley).

Gotta run, Regards,
 
Hornresp does not indicate the losses at high power levels, according to the experts that have actually build and measured both bass-reflex and tapped horn enclosures that is where the TH really shines.
TH "shine" with stiff cones, but have lots of losses with lightweight cones like the 3015LF.

In post # 1492, “Single sheet TH challenge”, Crescendo measured his 3015LF loaded, 1/2” Aruco plywood SS15 cabinets at:

70Hz: 103.2 dBC, 2.83 v at one meter
70Hz, 124.7dBC, QSC PLX3402 amplifier “just at clip” ( about 75 volts, 700 watts at 8 ohm)

Had there been a linear voltage in/SPL out relationship, 700 watts/75 volts would have resulted in about a 28.5 dB increase in SPL, 131.7 dBC.

The cabinet fell far short of 131.7 dBC.
131.7-124.7 = 7 dB of power compression.

What % of power compression is from voice coil heat, exceeding Xmax, cone flex, or wood deflection is conjecture.
On a (presumably) short test, the voice coil should not heat much, exceeding Xmax, cone flex and wood deflection are the more likely dominant compression features in Cresendo’s test.

Tom Danley mentioned a 3 dB under prediction measured loss in the upper range of a large, multiple 18” cabinet. It required stepping up from 3/4” to one inch Baltic Birch with more extensive bracing to get the SPL up to the predicted level. Ended up weighing a lot more than the prototype.

Jim (jbell, the SS15 designer) mentioned some 3/8" deflection of the SS15 front panel at high power, that could amount to almost half of the measured upper power compression losses.

The reduction in the SS15 level at high voltage seems even worse than the FLH results shown in post #13 of this thread.

As Jim has mentioned before, the SS15 was designed to be efficient, lightweight, and quick to build.
It succeeds on those counts.

Art
 
turbodawg:
Oh man... I'd completely blanked that train wreck of a conversation out of my mind... thanks for the 'way back'

Art: (weltersys)

Yep, those measurements that you mentioned (here and in the past) show a bunch of compression. I usually run out of gas at 128 - 128.5... no matter what I do to the ss15 with a 3015lf, that's about where it runs out of gas... with the construction methods that I choose to use. Because of that, I've moved on to an ss18... but it's something that deserves it's own set of detailed plans, instructional video, etc... so probably not something that is a DIYaudio topic, more of it's own website topic.

Where the OP has 3015lf's... and the ss15's successes are pretty well documented on DIYaudio, as well as other boards -- it's the best chance of success I know of in this particular case.
 
Hi Robin N Zone,

As jbell is bringing up the "SS18" maybe I should add to what I said in Post #22: if you put your 3015LF into Xoc1's design for an 18" woofer you'll have a very nice TH. Naturally, it'll be bigger than the SS15 but it will reach a little lower. By the way, in that big a box don't run the input into the 3015LF past eg=45V with the 32Hz/24dB/octave LR high pass that jbell recommended in Post #19, at that input level the speaker just exceeds Xmax (on paper), and as weltersys already pointed out any additional input power will not buy you anything (well, maybe distortion, torn diaphragm....).

I'll attach some Hornresp screen prints:

Regards,
 

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While I'm just randomly throwing ideas out there, the Cubo Sub also came to mind:

http://www.diyaudio.com/forums/subw...-its-data-bass-should-i-do-2.html#post3340777

Here's a measurement of a cubo sub vs. 30hz tuned BR design. Both are 300L and use a Precision Devices PD1850. Much more below 35hz from the BR, but the Cubo is +5db sensitive from 40-100 hz+. More discussion in the linked thread.

http://www.diyaudio.com/forums/subwoofers/192707-best-sub-5.html

231630d1311010417-best-sub-cubosubvreflex.jpg


Here it is against a more conventional kilomax driver:

232206d1311332368-best-sub-cubosubpdvreflexkm.jpg
 
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Hello Guys!

Sorry I havent answered for a few days, work got in the way..

I´ve been trying to read as much as I can on the SS15 and other designs suggested here, there sure is a lot to read :)

I really like the SS15, feels like a very good alternative to my T48s. But, I wouldnt mind to go a bit lower than the SS15, 35hz would be nice:) But then I´d need a bigger box..

Like JBell says, the SS15 seems like a very good compromise for the 3015LF:)

tb46, I like the ideas that popped up here about cone corretion, gonna read up a bit more on that:) Is that something that someone has tried?

Is there something like a "final" drawing of the SS15, is that the one that is linked in the first post of the single sheet challenge thread?

Jbell, I see that you often used to say something like the T48 is 10-13db down at 40hz compared to 100, but alot of measurements of the SS15 seems to tell the same story? about 10db down at 40? But there seems to be different measurements and a bunch of different simulation curves?

I just want to be relatively sure that I´d get the same or better performance from a pair of SS15s as I get from my pair of T48s:) I do understand that I´ll loose some 100hz bass, but that doesnt matter, I always eq that area down anyways:)

If I can get very similar performance in a cab half the size, that would be truly fantastic:) If I even can get a bit more 40-50hz that would be amazing:) I´d be able to bring 4 SS15s in about the same packspace as my 2 T48s, so should be able to go louder:)

The consensus seems to be that the SS15 is the best compromise cab for the 3015LF:)

Have anyone compared the two directly? Maybe it comes later in the SS thread, have only read about 70pages.. I thought it was interesting to see that Dave Non-Zero (who I "known" from the BFM forum) liked the SS15, I guess he actually compared them.

Jbell, you mention that your Stadium horn goes to 30hz? But I´ve seen you write 40hz in your thread about them, did that change?:)

If one crosses a SS15 at 32hz, will there be any noticable output at 32-40hz? I see that the response drops rather sharply at above 40hz? Maybe if I run 4-6 of them in a cluster?

tb46, I´m gonna look into the Xoc1´s design that you suggest in post #26, but it feels like something like that has to be the next project, with a better driver:)

I think I given up on going below 40hz with the drivers I have, so it feels like SS15 is the way to go for now:) The only question is which "version" to build:p What about handles in that cab btw, would it work with some normal dishhandles or cornerhandles? How have those of you that have built them done?

Thanks again for all answers guys! So much to read on this forum :)

//Robin
 
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here is another option for the 3015
http://www.diyaudio.com/forums/subwoofers/185836-3015lf-th-35-40hz-but-only-20-deep-help.html
the problem is that excurion risez rapidly under fb ,so a hpf to low is going to distort/destroy the driver.
the model in the above topic has much less cr (puting less stres on the cone)and is tuned lower@the expnce of lower output.

Thanks for the link Epa! I´ve looked at that design also, and it is interesting:) I do like that it goes a bit lower than the SS15, I dont like that it has less output however ;) I know I know, no free lunches :p

About the 32hz highpass on the SS15, I do understand that going to low might damage the driver, thats why I asked, since Jbell recommended it be crossed that low? I think I read something that it got some extra cooling thanks to more excursion or something like that?

So it looks like we have 3 contenders for my drivers:
Jbell´s SS15
Xoc1´s TH18
Bjorno´s T-QWP

I do like that the SS15 seems to give me more or less the same or even better output (not at 100hz obviusly) as my T48s in a cab half the size, and that it uses 12mm ply. But I´m not really restricted to just 1 sheet per cab, and a bit more extension would be nice... descisions descisions..

//Robin

Time to read a bit more...
 
Hi Robin N Zone,

Post #29: "...tb46, I like the ideas that popped up here about cone corretion, gonna read up a bit more on that Is that something that someone has tried?

Is there something like a "final" drawing of the SS15, is that the one that is linked in the first post of the single sheet challenge thread?..."

http://www.diyaudio.com/forums/subwoofers/170771-single-sheet-th-challenge.html

Posts #74 and 82 for the original SS15. In Post #1921 PASC shows one form of cone correction applied to the standard SS15.

Post #1499 has jbell's sketch on a slightly enlarged/modified SS15 w/ cone correction, it should be easy for you to extract a drawing from that (also, see Post #1503, etc.). In Post #1564 jmbro has a picture of a sketup model. I don't know if jbell has any additional data on this experiment.

Regards,
 
Hi Y'all,

If somebody could, please, fill in the missing dimensions in the drawing below, we can arrive at an accurate dimension for the cone correction (multiple answers will be fine, that way we have some controls to look at):

Regards,
 

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I can measure one of mine tomorrow, I have two still unpacked:)
Mine are from 2011, ordered them the 6e of may 2011, so they should be the newer version?

Would be nice with a slightly updated SS15 to fit better? with the new 3015LF, with cone correction:)

I´ve finally read the whole SS15 thread, and Jbell´s v2 looks really intersting:)

I´m not really constrained by the single sheet requirement, but I do like it, but could go for a bit bigger, but only a little, to get really good 40hz, but maybe Jbell´s v2 get that anyway? :)
 
Hi tb46
What is it that you are proposing to do.
As I see it there are issues with the SS15 design, but overall it is successful.
The folding of the horn looks fairly uneven when unfolded, but the restrictions, which coincide with the folds are what give the SS15 its overall horn length.
Take away the restrictions and try to smooth out the taper and the horn length is shortened by a significant amount.
The only dimension it the SS15 design that is significant when trying to get all the parts from a single sheet is the front to back dimension which being just over 600mm allows 2 panels to be cut from the 1220mm sheet. Everything else can be adjusted.
To cut a long story short if you want to redraw the horn adding a cone correcting dip at S2 and you want to smooth out the expansion and keep to a single sheet the best way to achieve that is by making the entire cabinet narrower and taller.
The other design aspect of the SS15 that could be changed is the timber thickness.
Increasing the thickness of the timber would hep to reduce the losses at higher levels but introducing miters and still trying to keep to a single sheet soon becomes difficult.
Regards Xoc1
 
But I feel they are lacking when we are playing stuff like Hardstyle or Hardcore, some Psytrance or even some modern House music
I've compared the T48 against a cabinet that goes deeper as the T48 and has flatter response (but less of that 100 -120 Hz BFM-thump). For the EDM mentioned the T48 didn't lack (for hardcore not at all actually).
Using the cabinet that goes deeper at parties I don't feel I'm missing much for hardcore and psy if I cross at 40 -45 Hz.

If your driver choice is limited to the 3015LF, per driver the T48 is still a good choice for those styles. Personally I didn't found it's size a real bother due to the lowish weight.

Against a cabinet like Xoc1´s TH18 it will likely still sound louder at 120 Hz but be swamped in the 30 - 60 Hz region. You would need music that excels at 30 - 35 Hz to really feel the difference. I don't feel the EDM mentioned falls that much in that category.

That being said, at home I like to listen to early hardstyle and psytrance on a sub that goes to 33 Hz and has a small thumb on 63 Hz.
When using a sub that dives down to 15-ish Hz, it adds so much thickness to the bass it's not a real benefit.
Most EDM- producers do not use subs that go that deep, so strictly speaking they do not now what they add (or leave in).

Have you tried V-plating?

Best regards
 
I see that post 1499 in the SS Challenge Thread is definitely the layout to go for
http://www.diyaudio.com/forums/subwoofers/170771-single-sheet-th-challenge-150.html#post3028139
As Jbell says in that post :
"A bit of 'S2 cone correction' instead of a compression plate.1" taller and 1" narrower...and the SS15 can now hit with authority an honest to goodness 40hz. "


Any comparisons to see if the predicted "authority" translated in to an actual SPL increase at 40 Hz, and what that level was?
 
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