Lii Audio 15" full range

Proud owner here, as of last week. I threw them up onto a pair of table leg stands, just to be sure they're OK after shipping, as a Saturday morning effort. They are.

I'm quite happy with the sound. Now, I need to mount them on an OB design of some sort. Any assistance would be much appreciated!

I was casually thinking I might replicate Decware's "Betsy" design and would like to understand why the "barrel" shape works. Caintuck Audio, the originator of the Betsy, also offers "tombstone" style baffle boards with parallel sides.

Lucky for me, there's a Washington state surplus store very near to where I live, which has tables, desks and other MDF based bench-tops at very inexpensive prices. My plan is to pick something up and start cutting. If I'm lucky, there'll be two of something I could cut into a Betsy, or something with parallel sides I can simply trim to height.

The typical desk or workbench top laminate - my worry is how to get a clean edged, say, 16" circular cut in something that may be 2" thick. I like the standing mass of a baffle like that, but I dread trying to make such a cutout with something like a Sawzall. The Decware speaker mounting is flush with the baffle surface - looks really nice - However I assume the only way to do that is with a router...

Hopefully I'll be choosing a couple of hunks of material to work with this coming week. I could have got a pair of matching 6' diameter 2" thick tables - which would have easily yielded a pair of Decware style Betsy Baffles - for $5 each. I couldnt have lifted them atop my Subaru forrester if I wanted to. What practical width should I be setting my sights on for this 15" and its free air of ~50 Hz?

Thanks!
 

Attachments

  • DSC01907.jpg
    DSC01907.jpg
    423.3 KB · Views: 3,628
  • Lii F15.jpg
    Lii F15.jpg
    435.2 KB · Views: 3,638
Last edited:
I had a look on line for the "old wharfdale baffle" and found this;

I like the comment that "There is no particular virtue in its dimensions". Also the tilt-back angle wasnt shown in the drawing. Apparently the "Betsy" stands up straight and I was wondering if I should incorporate some backward tilt into the stand part.

I'm also wondering about speaker height. I'd like to keep the speaker center 20 - 24" up off the floor (to match my seated ear height) but I understand this may be wrong thinking on my part, as there may be as much to lose in some other performance aspect if I do this.

I can see that the speaker position on the baffle correspondes to the wing shape of the sides. If I flipped the whole thing 180 (conceptually), would I get combing due to the speaker height being more toward this ear height I think I want?
 

Attachments

  • Wharfdale.jpg
    Wharfdale.jpg
    75.3 KB · Views: 3,092
  • Wharfdale1.jpg
    Wharfdale1.jpg
    183 KB · Views: 2,947
  • Wharfdale2.jpg
    Wharfdale2.jpg
    113.4 KB · Views: 2,878
Last edited:
I had a look on line for the "old wharfdale baffle" and found this;

I like the comment that "There is no particular virtue in its dimensions". Also the tilt-back angle wasnt shown in the drawing.

I'm also wondering about speaker height. I'd like to keep the speaker center 20 - 24" up off the floor (to match my seated ear height) but I understand this may be wrong thinking on my part, as there may be as much to lose in some other performance aspect if I do this.

Gilbert Briggs was being a touch 'British' with that one; it was actually a rather well designed baffle. Mixture of accident and design perhaps, but it's popular. The driver position is deliberately low to pick up some boundary gain for e.g.
 
The Edge program shows best bass with a wide baffle and the driver off to one side. The wider side of the baffle can be turned back 90% so the from looks like the driver is centered.

I like that idea, folding the baffle back on one side only means less of a problem with cavity resonance and the overall narrower baffle means less blockage of the front wall reflection.
 
@djn, scootjoplin,

Yes, I was shown a pile of apparently new tables and the lady there promised she'd make them available on Tuesday (tomorrow). These will fit in the back of the Subaru and I can probably afford 3 or 4 of them; use two, split one to use for a single wing on each "cab".

(And one in case I screw up a cut on one, either way the remainder becomes the base / stand construction)

About those cuts, let's say I'm cutting across or around something with counter top laminate on it already. What tool method would make laser fine edging? I'm afraid if I just cut across one of these with the tablesaw, it's just going to shred the laminate at the cut. Anyone know any tricks to working with laminated MDF using a rotary blade?

To make the speaker cutout, I was actually dreaming up making a tool that could get me a clean edge on the laminate. Sort of a "boy who harnessed the wind" affair. Unsure if they make a hacksaw-style blade for my harbor freight "Chicago" sawzall, but that's where I'll first start to look for a solution.

I'm going to mount the speaker not recessed on the top surface, so it'll cover any cutout anomalies. I've been thinking of a second (1/4"?) wood finish laminate to shore up around the speaker basket top, perhaps I could cut a decent decorative pattern into it that would also break up the surface from being so flat. And it would be nice to get some kind of screen or cloth over these and great if I can figure a way to incorporate that into this second laminate idea.

We'll see what tomorrow holds. If successful, I'll post pictures of the materials. There's a place that sells large slabs of granite in the same parking lot. If I'm lucky at the surplus place, maybe I'll stop by there and ask "how much for one of these in granite? with a 16" hole in it?" Thanks,
 
Last edited:
JJ look here....OB Theory

Yes, I was thinking of OB theory when I read above, but I didn't want to break JJ's dreams.
You want a driver that plays consistently the bass, because it will need to be equalized by passive or active means.
Since your driver is already G-normous, you wouldn't want to push its bass abilities because it's full BW and because of IMD, and generally it's the big one to generate bass.
So you'll need a shelving HP filter for the Lil 15" and another woofer for the bass. Probably a 4 Ω or 2+2Ω 15" woofer for car audio could do the job, probably two and a dedicated amplifier with electronic crossover, who knows?
:clock:
 
Well, here it is. (My wife went with me, so I didnt, er, get a chance to stop at the granite store...) I got 4 of them and they charged me next to nothing for a brand new table top.

They weigh 53 lbs each, very close to my max safe lift limit. 30" wide, and I'll probably be using somewhat less than their 59.5" height but I'd like to keep the vertical orientation.

I'm hoping someone can suggest where to arrange the 15" driver cutout on the surface, if different than the obvious spot. I'm OK with it being offset from the circular top, if sonic benefits are a result.

As all of it is a compromise, I'd simply like to do the best I can with this set of material. I'm OK with losing the octave below this speakers 60 Hz Fs; these cones are pretty tight and not suspended at all like the Wharfdale woofers.

Thanks!
 

Attachments

  • DSC01909.jpg
    DSC01909.jpg
    374.7 KB · Views: 1,261
Vertically, at some odd harmonic, so normally at H*0.21, 0.349, 0.424.

Horizontally, at some acoustic or golden ratio, especially since it's a 1/2 round top. The pioneers seemed fond of the industrial design's 1:1.4142:2 while folks nowadays tend to use the 0.618:1:1.618 golden ratio, but there's lots of others to choose from: http://docshare04.docshare.tips/files/28838/288382396.pdf

Room ratio formula: Chapter 13, fig. 13-6

Room ratio chart with some already done: Chapter 13, fig. 13-9.

GM