Full Range-ifying a custom 115 cab

[DukeLeJeune]

Duke, looking at the response curve on USSPEAKER, I think I'm just not reading it right. The "huge 1.2kHz peak" that you also referenced in my original build seems like only 3dBs at 1.5-2kHz.

Are you looking at the 3015LF, or the 3015?

Here's the 3015LF:

[Invalid or Expired Link Removed]

The "baseline" SPL is what you see from 150 to 400 Hz. Then we bump up by a dB or so at 500 Hz, and then there's a 5 dB peak on top of that a 1.2 kHz. So the way I read things, it's a 6 dB peak. To me that's "huge", but perhaps I'm just a wuss.

By the way, at one time I set out to design a passive crossover for a 3015LF + horn, and the lowpass section I ended up with was EXACTLY the same as greenboy's. I was horrified when I looked at his crossover design and realized that if I sold this as a kit, everyone would think I copied the lowpass section from greenboy. But the take-home lesson for anyone else would be that, with my fancy-pants computator and mikerophones, the best I could do was a duplicate of greenboy's work. He is really, really good.

I'd go with greenboy's crossover in a different cab before I'd go with a different crossover in greenboy's cab. Not to put down his cab design, but that is a cat that can legitimately be skinned more than one way (though he pretty much nailed the optimum there as well).

 

[Patman27]

Yes, I'm using the Kappalite 3015LF. Did I link you the wrong one?
I see what you mean, Duke. I guess it didn't really register until just now.

In that case, would you suggest I pull down crossover specs for greenboy's 15+6, and make a mid enclosure for the 18 Sound 6.5"? I mean, I think my cab's relatively large compared to other production models. It's taller and deeper than the three other 115s that I compared it to before starting the build (Son of Bertha, Eden 115, another one that I happen to forget at the moment).

 

[greenboy]

Can you get a 6" mid on your baffle and not have it too close to the edge? It looks like it might go in at the wide side. Look at my 15/6tube plan (linked via the fEarful wiki).

If not, go external. Keep driver spacing as close as is practical.

I didn't do any math here on you net box cubes, but I can tell you that my crossover is going to be closer than the generics at matching both your drivers' free air characteristics, and what happens once they are enclosed in your cab's internal space.

 

[greenboy]

Oh, yeah, Patman - if the 15/6tube flat plan confuses you, there is a 3d model of the cab too, viewable in google sketchup. That stuff is linked near the bottom of the fEarful wiki.

And thanks, Duke, for your kind words. But doesn't that kind of make us both suspect, you being from the home of these guys?:

 

[Patman27]

Can you get a 6" mid on your baffle and not have it too close to the edge?

[warm, fuzzy feeling] Duke, greenboy, and everyone else, thank you so much for all of your input! [/feeling]

By the way, I have more detailed pictures on my site, including some more (embarrassingly) low quality shots and finished-product snappies.

With a measuring tape, I found that 6.5" is just going to fit. Hopefully the actual cutout sizes for each speaker would leave adequate space for some more 5/8" ply.
How would you recommend I add in a mid chamber? Glue/black-colored screws from the outside, or just good clamping and glue? Corner blocks screwed/glued in from the inside?

 

[greenboy]

Ah, whatever you feel comfortable with. Just go in from the woofer hole, and make sure cuts for the mid chamber pieces are fairly straight/flat. Screws are fine if you don't mid them. Run a bead on either side of pieces to make sure there is a good seal after the pieces are glued/screwed down.

Make sure you have a well-placed 1/4 hole to run wires into the mid chamber before the pieces get attached.

 

[Patman27]

Make sure you have a well-placed 1/4 hole to run wires into the mid chamber before the pieces get attached.

do you usually seal that with anything, or just leave it open?

 

[greenboy]

Duct tape.

You could get fancier, but it doesn't hurt to have a little air relief anyway.