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pjanda1 19th May 2010 07:18 PM

BetsyK Simple TL
4 Attachment(s)
I've been talking about this box for a few months, and I finally completed some graphics. This is a folded TL/TQWT that I modeled in Horn Response. I have built a couple of pairs, and they sound great! They started as a project for my brother and sister-in-law who needed moderately sized enclosures. I like this box over vented boxes due to the intrinsic bracing and midbass gain. I have used them against a wall and in corners. You could make the terminus front facing, but I'd make it as pictured as long as you can get them an inch from the wall. Of course, you could also make them side facing.

I have them stuffed with a pound and a half of polyfill per box. I have it concentrated towards the top, and tapering down to stop just above the folds. The brace is arbitrary. You could leave it out, or you could do something more substantial. The drawing assumes 3/4" material. I used "Arauco" ply, which is an almost entirely void free pine that costs less than $25 a sheet.

This is my favorite reasonably sized box for the BetsyK's. I hope you'll ask questions and try them!

Wild Burro Audio Labs - DIY Full Range Speakers

pjanda1 20th May 2010 02:34 AM

Oops! I was just pondering the drawing I posted, and it occurred to me that I screwed up badly. As you can see, the box doesn't have sides. That was intentional, and it is assumed that 3/4" sides cover the whole thing. However, the width of the cabinet with sides is 12"! I show the "guts" as being 12" wide, but they are really 10.5". A finished cabinet would be 12"w x 13d" x 44"h, not 13.5" wide as the drawing would seem to indicate.

Part of the design goal was to make very efficient use of both floor space and materials. So, you can get a pair of cabinets out of a sheet and a half of ply (many places sell half sheets). I get all the front, back and sides out of one piece. First, I cut two 44" pieces of the 8' length (allowing you to cut off the edges if they are damaged or not square). The, I cut each of those into two 10.5" (fronts and backs) and 13" (sides) panels. That allows you an extra inch for kerf (I use a thick plywood blade). So, you waste very, very little of the entire sheet and the grain goes up and down on your speaker. Then, I cut strips out of the other half panel for tops, bottoms and braces.

hope that makes sense,

Wild Burro Audio Labs - DIY Full Range Speakers

nic6paul 21st May 2010 12:14 AM

Paul I have been waiting for something a bit smaller to come along. I think the next time I am at menards or one of the big box shops I will pick up arauco plywood.

kenpeter 21st May 2010 07:03 AM

1 Attachment(s)
Vaguely what I had in mind. Probably won't stick religously to
the original 3rd K12 cab I was unsucessfully trying to sketch.
There are measurement discrepancies I've yet to resolve. I'm
just gonna wing it... In Styrofoam, of course...

Yes, I'm aware this cab is scale for 12, and BetsyK is an 8.
But we already know these two like each other, except for
the eyelet thing. Effect of foam is the only real gamble...
Aruco definately where I'd go next if the Foam don't cut it.

ejfud 6th October 2010 03:21 AM

Anybody built one of these yet?

How's the bass response?

tweakk 3rd June 2011 02:02 AM

Hey Paul,

I just got off the phone with a pro cabinet-maker and he's ordering the materials tomorrow and building a pair of your TLs for me.. 100% hardwood baltic-birch ply. I'll post pics when it's done.


freddi 3rd June 2011 02:38 AM

hi Kenpeter - did you catch the thread of the guy on the Karlson forum who landed a pair of the elusive "3rd K12"? - he loaded those with EV 12L - maybe you can get some dimensions - his are almost square at the bottom
Hello from a newbie - about to get my first set of karlsonettes

tweakk 18th June 2011 02:34 AM

3 Attachment(s)

My Simple TL with Founteck NEO 3.5H ribbon tweeters. 100% hardwood baltic-birch laminated with Wilson Art Xanadu.

Not hooked-up yet...

tweakk 18th June 2011 02:35 AM

2 Attachment(s)

ejfud 18th June 2011 02:05 PM

Great build!

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