"Best" PA subdesign for the Eminence Kappalite 3015LF - Page 8 - diyAudio
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Old 21st April 2013, 01:19 AM   #71
Xoc1 is offline Xoc1  United Kingdom
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I have not worked out a cone correction for the 3015lf
I have a correction curve for the Fane XB15 on a 18mm baffle as an example.
Firstly I model the cone volume and baffle cut out, and measure the cross section at different positions.
I then input the areas into a spreadsheet and calculate the equivalent height if the area was the full width of the speaker (in your case 503mm)
This gives me a cone correction curve that I can plot in the cad as an additional line that is used to calculate the folded volume, instead of the line of the baffle. The cone correction line is plotted on the top face of the baffle. The cone correction is simplified and averaged to 3 segments to be equivalent to the 3 timber sections.
This then gives a resultant horn section (as the 3rd screen grab.)
In your case I think you need to make S2 bigger, this seems to fill in the dip!
Use the Hornresp Loudspeaker Wizard to adjust S2 etc dynamically to see what works and adjust your fold accordingly. Then remeasure the unfolded horn and sim it again. Sometimes it takes a few iterations to get a reasonable result.
Regards Xoc1
Attached Images
File Type: jpg XB 15 section.jpg (18.3 KB, 229 views)
File Type: jpg XB 15 section sheet.jpg (91.0 KB, 228 views)
File Type: jpg C C Hornfold.jpg (23.1 KB, 231 views)
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Old 21st April 2013, 01:42 PM   #72
jbell is offline jbell  United States
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Quote:
Originally Posted by Robin N Zone View Post
Jbell,you still havent told us if you ever built your extended/v2 version that this is based on
Regards
Robin
yes, i've built MANY variations on the ss15. Most of them net minus in some respects to the original. Every time I get more 40hz, I get overall less total spl. In the end, total spl seems to rule the day.

The things that I have done that are net positives.

The 'wasted triangle' I eliminate to make S1 bigger, all else equal on original ss15. (very small but positive change) Big S2 actually makes cabinet lower without going longer. Problem is making that section 'rigid' enough. I typically take a piece of the round cutout and make a stiffening plate through that area. If your construction techniques aren't up to par, just build it the original way.

compression plate with 400-500cm opening. It really helps when 'wound up' to keep the cone 'linear'

2 -- dowell or 'broomstick' bracing about 6" apart. If you find one of those really long drill bits made to go through house walls (about 36" long) you can drill a couple holes from front to back and use dowells with 'rings' and glue where you go through each board.

2" vertical strip of wood attached to front panel in the center, (rt.angle to the front panel) it flexes ALOT there.

2" strip of wood attached to bottom panel from front to back -- bottom panel flexes alot.
metal grill on mouth to eliminate flex.

The original 2 angle boards from top/back and back/bottom. make a pair of them, 6" apart.

I've played with several different angle baffles in the upper back, no clear winner there, however smaller is better and it makes a great places for making 'routed out' handles and a recessed area for a speakon.

hope that helps... Really -- the original ss15 is just a pretty nice balanced cabinet for the 3015lf.
Good luck, and post pics/measurements when you make sawdust.

Last edited by jbell; 21st April 2013 at 01:45 PM.
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Old 21st April 2013, 03:22 PM   #73
tb46 is offline tb46  United States
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Hi Y'all,

Some more ponderings on the SS15 :-):

I have not build or used a SS15, but I have tried on paper to improve on it. My result is, that the SS15 is a very good compromise, I feel a cone-corrected version should take that into account, and I furthermore think, that neither Hornresp nor AkAbak can provide a simulation that reflects what this driver/box combination is going to do at high power.

Particularly not the small S2 (high S2 compression) version of the cone-corrected SS15 (SS15CC?).

Someone has to build and measure, and compare models with different reduced S2s, e.g.: in jbells sketch he has about 1" between baffle and the other side of the duct, but this may well be with a compression plate, that would alter the geometry (it also would alter the Hornresp model, as you than have a throat chamber with an opening into the horn @ S2 (or two openings if you pull the cone compression all the way to the baffle, "opening" #1 points towards S3, and "opening" #2 points towards S1).

I'll attach a pdf with a look at Robin's first cone corrected drawing.

Regards,
Attached Files
File Type: pdf SS15_cone_correction_measurements.pdf (158.9 KB, 39 views)
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Old 21st April 2013, 04:11 PM   #74
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Thanks again guys

I really appreciate all the help and suggestions!

Martin, thanks for explaining your thinking on the conecorrection, looks very logical to me.
In my first attempt I just had a offset from an averaged coneshape, but I do see that your way makes more sense.
Btw, did you ever make a "final" conecorrected version of your TH18? And do you think it would be even a half good idea to build it in 12mm birch (more bracing) and the 3015lf? It looked like the driver simmed rather good in your cab if nothing else.

Jbell, thanks for your answers and tips
I must say that Im kinda leaning against a more original SS15, but maybe with the conecorretion, but maybe not as extreme as the one I drew first.
While Id really like to spend more time on optimising the design, I more or less have a deadline, I need two more subs on saturday.. and Id prefer to not need to rent subs, I probably gonna need to rent 2 Pioneer CDJ-2000s to manage the two gigs so :P

Id like to start building tomorrow, but that doesnt mean that I cant build a different version of the SS15 in the near future, but would of course prefer to build a version that Id stay with for a while.

I was thinking to put routered handles in the upper back corner, with either a corner "reflector" the whole way, or perhaps just covers around handles? Seems to me that it wont be much of a loss to loose some volume in the corner?

Oliver, thanks for spending all the time you do with drawings and all SS15CC seems like a good name for the cone corrected version, lets go with that?

I will probably only build one version of the SS15CC now, but who knows:P Dont know about any other builds here in Sweden to compare to sadly..

Now, back to cad and hornresp to see if I can get it a bit better, the sim looks a lot better with Olivers suggested 512cm^2 S2, big difference, so Ill make a cad drawing with that and his suggestion on S3 location.

Ill post when I have something to post

//Robin
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Old 21st April 2013, 08:58 PM   #75
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So, the next cad drawing is "ready".
Ive calculated the conecorrection the way that Xoc1 showed earlier today, and used that together with the suggestion of 512cm^2 S2, and moved S3 to the second 180bend.
I calculated the area that the driver takes up at the S4 location, and put the equivalent in the Cad. This whole operation lost me about 10cm of hornpath.

It does sim better for sure, so thanks guys Im still not sure if panel I, H and G have a good shape or not, probably possible to adjust those some more.
I just took the cone correction curve and moved it to get 101mm S2. I dont really know how Martin gets his shapes, I cant really see the connection between his panelshape and the cone correctionshape, but Im sure there is some nice correlation

I also made a simple comparison of relative sizes between, from left to right, the SS15CC, the TH18 (in 12mm ply) and my Titan48s. They are all lined up with the horn openings to the floor and front.
The SS15CC sure is a lot smaller than the T48s But the TH18 are quite a lot smaller also, and it looks like I could fit 4 of those in my van, where I can only get in 2 T48s, and that would be nice

So, now Im basically thinking: Should I spend many more hours trying to get a good design from what Ive started with the SS15CC, which may or may not turn out better than the original version with say a smaller baffle opening.

Or, just go for the standard SS15 with the simple mods that Jbell suggested earliger?

Or, since I dont really need to stick to one sheet, just go with the Xoc1 TH18, but in 12mm ply, afterall, it will only get an 3015LF, not a multiKW 18", so should be fine with some extra braces, I think?

I do like the response that the 3015LF seems to get in the TH18, and if Im willing to go bigger than the SS15, there is no point in trying to design something myself when Martin has already made such a nice design

The downside of the TH18 with a 3015LF would be that it is a rather big cab, and as such really deserves a better driver I think, but it would get me more out of the drivers I have on hand now..

And it would be nice with subs the size of the SS15 for sure.
This is the kind of decisions Im really bad at :P

Ive attached the cad drawing and a Hornresp export for the SS15CC v2.

Regards
Robin
Attached Images
File Type: jpg SS15CC TH18 T48 Comp1.jpg (48.8 KB, 215 views)
File Type: jpg SS15CC TH18 T48 Comp2.jpg (20.9 KB, 204 views)
Attached Files
File Type: pdf JBells SS15CC RL 2013-04-21.pdf (72.1 KB, 33 views)
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Old 22nd April 2013, 05:46 AM   #76
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Apperently it didnt work to post a rarfile, so here comes a link to a folder on my google drive, there is an R14 version of the cad file, and 2007 version, and also the Hornresp export, and the size comparision drawing I made in 2007.dwg format.

https://drive.google.com/folderview?...1U&usp=sharing

Regards
Robin
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Old 22nd April 2013, 08:00 PM   #77
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Default So, version3 now :)

Oliver (TB46) gave me a suggestion earlier today, which gave more S1, and much nicer shape to the whole S3-S4 region, it did also sim better.

Attached is the drawing as a pdf, and a hornresp export.
The dwg in R14 format can be found at the same link to my google drive in the previuos post.

I ran a few sims of the original SS15, and also of a mod that Xoc1 posted a while back in the single sheet challenge thread.
None of those take the volume of the cone into account as far as I can see, neither in S2 or S4, so S2 gets bigger and S4 smaller in reality, which atleast in the sims gives more 40hz, less 60-100hz.

So it seems to me that taking the volume of the driver into account early on should jield a cad that performs closer to the sim, no?
If there is also a performance benefit, Im not to sure. See the attached pic that compares mine and Tb46s SS15CC v3 with the SS15 Xoc1 mod, when the later has the volume of the driver roughly added to S2, subtracted from S4.

The other point of the cone correction seems to be better cone control at high drivelevels, but we dont se that in the sims... Could a smaller cut out in the baffle(as Jbell suggested yesterday) on say the Xoc1 mod do much the same thing?

Not sure how to move forward now..

I think I need to make sawdust soon :P

Regards
Robin
Attached Images
File Type: jpg SS15 Xoc1 Mod vs SS15CC v3.jpg (87.8 KB, 57 views)
Attached Files
File Type: pdf J Bell SS15 Mod Xoc1 .PDF (83.7 KB, 23 views)
File Type: pdf JBells SS15CC RL v3 TB46 Mod 2013-04-22.pdf (69.6 KB, 29 views)
File Type: txt SS15CC_v3.txt (441 Bytes, 13 views)
File Type: txt SS15_Xoc1_Mod.txt (431 Bytes, 10 views)
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Old 22nd April 2013, 09:30 PM   #78
Xoc1 is offline Xoc1  United Kingdom
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The SS15 version I drew predates my use of any TH cone correction.
The TB46 mod version looks good.
The cone correction should ensure the bottom end response is fairly close to the sim.
Actual performance of the cab will be very dependent on your build and how well you brace the cabinet.
Regards Martin (Xoc1)
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Old 23rd April 2013, 07:32 AM   #79
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Martin, thanks for your answers!
Yes, I guessed that was the case for your version of the SS15. But still, when I roughly added/subtracted the volumes of the driver, your version simmed better then "mine" I think, so it really seems like a large S2 is the way to go for the Kappalite, maybe even more so with the newer ones.

So my question would be, what other benefits will the cone correction give, apart from making the sim closer to reality?
Im not convinced that the V-loading that Ive been looking at would give all that much more even loading of the cone, it feels almost more uneven than just a flat panel. I mean, the volume towards S1 dont really move anywhere?

The main advantage that I can see with that style of conecorrection and folding is that it gives a longer path, but that doesnt seem to do any good, atleast not when the box size is the same and the driver is the 3015LF.

Using a smaller round opening in the baffle, like the 4-500cm^2 that Jbell suggest, should create a more even load on the driver I would think, and increase the compression a bit.

One of the gigs we had booked on saturday just got moved 3 weeks, so now Im not in a desperate need for 2more subs, so there is some more time to design something good now

Regards
Robin
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Old 3rd June 2013, 10:47 PM   #80
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Default Long time no post! ;)

Hello again guys!

Been a bit busy the last few weeks, sadly only partially with subwoofer design...

But Ive done a bit atleast, and Ive decided on what direction and such, finalising a version of the SS15, mainly based on the one that Xoc1 did a while back, but slightly wider and some other small changes, to optimise the sheet even further
Ive decided to do a bit more bracing than the "standard" SS15, and to cheat a bit, Ill make the braces out of 9mm BB, and use a full sheet of 12mm BB for the rest, so it wont really be an SS15, but thats fine be me

Ive made a few versions of the drawings and sims with a the conecorrection, and I just cant get it to sim better than Xoc1s version, even when I take the cone into consideration on the Xoc1 design.
A large S2 seems to be critical for the newer Kappalites, so Im going with the Xoc1 (close to Jbells original) basedesign, and tweak it a bit

One thing that Jbell have suggested is to reduce the opening in the baffle to something like 3-400cm^2, much the same way the baffle in my Titans are made. Im thinking that a round opening would load the cone more evenly than a square opening or the "double S shape" opening that was suggested for Xoc1s TH18 a while back.
Any other suggestions about that? What shape would be best? I guess that max performance and max durability of the driver might not go hand in hand here, and Id opt for durability here.

I would then need to mount the driver on a spacer, 12mm should be best, then Ill get about 18mm clearance for the cone and surround, xlim is 17mm, so if the cone hits the baffle it will not really matter much :P
Perhaps 9mm spacer could be used, but then Ill only get about 15mm clearance, with an xmax of 11mm it should work fine, but a bit to small margin I guess? I dont think my current amps can drive the 3015LF to 15mm excursion, even less likely considering powercompression and limiters set to maybe max 60-65V, but still...

Im also thinking about putting a smallish cornerbrace/"reflector" in the lower corner, without constricting the hornpath at all, so really only taking away nonlinear extra volume in the hornpath. This is mainly to get a cut away lower corner, and then save a bit of wood on the bottom and back panels. otherwise Xoc1s interior hornpanels dont actually fit on the one sheet
Also, I can then put some nice 80mm wheels in the lower corner, I know I know, small cabs, not really necessary to have wheels, but Im building these to get smaller easier to handle alone cabs so theyll have wheels
Anyone seeing a big problem with a "reflector" like that?

Im also thinking of routing a handle in the top of the cab, a cutout in the top hornpanel, and 2 cutouts in the top, on each side, coverd with 45degree "reflectors" each side. More or less like a barhandle, only routed into the cab instead I know, loosing a bit of cabvolume there to, but must have handles, these will be rental cabs. My plan is that these will be light enough to lift in one hand, and it should work good to use that handle to roll them on the wheels, so wount need to lift the much anyway
This handle will also just take away nonlinear cornervolume in the cab, so hopefully not contstricting the path.

Id like to have routered handles in the sides also, but that might take away to much S1/S2 area, cause thats where theyd end up..

What do you guys think? Am I way of base here? I need to start building this week, for real this time :P

I can upload a pdf with the latest version of the drawing I have tomorrow

Thanks for all help guys!

//Robin
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