3015lf?

[Brett]

Originally Posted by wg_ski

Or at least, semi-pro...


It would be a welcome addition, as DIY tends to be a forbidden subject on the 'real' pro sound forums.

PSW seems open to it, at least if you approach it intelligently, and there is also Mogale's Speakerplans forum.

[davygrvy]

Originally Posted by mike james 533

Would anyone be willing to run the numbers if I share the measurements?

Another way to approach this, is to chose the driver first, then design the cab for the driver instead of the other way.

[mike james 533]

davygrvy, your right my way of going about this is bassackwards. lol My 24" wide T48's are just to big for my bad back to move around. So I have 2 -3015lf's to pull from them and reuse. I saw TDA audio's post with the tapped horns he did with the 12" and 18" versions, and that got me thinking about that design with the 3015lf. The thing I would like to change about the design is to add some height so rear wheels could be used and still dolly it. So I was looking to add 7.5" to the height, making it 39" tall by 17" wide.

[davygrvy]

Consider a tapped horn something like this. This is a very square config and should be easy to build as a single fold. IOW, deep and short. Or maybe a three-fold for taller and half as deep. 780cm^2 when done the width of the driver leaves about 9 inches on the other dimension.
3015LF_singlefold_parms.png
3015LF_singlefold_resp.png
3015LF_singlefold_disp.png
3015lf.txt

[BP1Fanatic]

Davygrvy, would you feed that TH the full 450w? I show a max input of 30w @ 9.6mm and a maybe a 25hz subsonic filter.

[davygrvy]

Full 450W, nope. Worst displacement (in band) is 40Hz for 36 volts (162W). Sharp high-pass it around 30 Hz or so. But your getting a sensitivity around 97 @ 60 Hz in halfspace. A larger mouth will bring efficiency up.

This is more like an HT sub cause it's smallish and that personally is what I'm going for when I get around to building it for myself.

[davygrvy]

This cab is about 6dB louder. Tuned a little higher and good to 43 volts. See jbell's threads please! Do not look to me for the last word.

[jbell]

bad back huh? sorry to hear that. looking for something TH-mini style? I did a quick sim at 50% of the volume of a 24" T48. Yea the T48 has it at 100hz , but the baby TH kicks hard at 50hz. This is an overlay of hornresp and lelands T48 at the 2007 shootout.

You could do a single fold of this easy enough, and have something easier on the back, that doesn't need a bunch of eq to flatten out.

just a thought.

[littlemike]

How low do you need to play? How big of a cabinet can you tolerate? Unlike a lot of drivers used in tapped horns, the 3015 really likes a big box.

Jbell's sim above looks good, really good for such a small cabinet. That is as smooth as anything I have come up with, and it is considerably smaller. You can get this driver to play lower, but you will not get it to play much louder with a larger tapped horn.

[littlemike]

OK, so Jim got me thinking....

It is possible to get to a 40 Hz cutoff, maintain 100 dB 1W efficiency +/- 3 dB from 35-140 Hz, and still be at 340 L (12 cubic feet), but it takes a slightly more esoteric tapped horn with dual tapers and a ported compression chamber. Still not at all bad for a box that is ~2'X2'X3'. Excursion becomes an issue above 250 watts below 50 Hz, but above 40 Hz, you remain within xmech (17 mm) until over 600 watts, though at this point, you really should think about making another cabinet or two.....

Details:

ID=23.40
Ang=2.0 x Pi
Eg=2.83
Rg=0.00
Fta=1.75
S1=450.00
S2=514.47
Con=11.50
F12=0.00
S2=514.47
S3=1000.00
Con=70.00
F23=0.00
S3=1000.00
S4=1662.58
Con=169.00
F34=0.00
S4=1662.58
S5=1800.00
Con=30.50
F45=0.00
Sd=881.10
Bl=18.50
Cms=1.40E-04
Rms=3.90
Mmd=85.40
Le=0.90
Re=5.30
TH=1
Vrc=0.00
Lrc=0.00
Ap1=401.00
Lpt=2.54
Vtc=3000.00
Atc=881.00
Com=Small 40 Hz TH 3015lf