Probably forgot to set it back to the normal value after I modeled it as such. The difference in the intended passband is mostly negligible. The inductor helps with the peaks a bit above 100Hz, but that's about it.
Metric conversion. I use the Cutlist output just to determine where all the cuts go... I do the actual cutting in metric down to the last millimeter.
That way, PL has less open spaces to fill. Also, because those internal panels are 11.8" wide and the plywood is 48," you want the cuts on supply piece 3 to be as accurate as possible. There's no real room for error. Part of the fun I had making the internal width as wide as possible and yet still fitting on three sheets of plywood.
I suspect variation in the individual drivers would make more of a sonic difference than a small rounding error in cutting boards. The few boxes I've made, I rounded to the nearest kerf width, and that seemed to serve me fine.
I'd complain about the mm, but I wish my country would switch to metric so I don't have to keep track of things like 51/64ths in my head while I'm working.
Speaking of drivers, I made a point over at my AVS forum thread I should make here as well. As per Hornresp simulations, this design will stay roughly within Xmax up to 300 watts. It'll take 600W or so for the drivers to approach Xmech.
Just wanted to caution people - try not to feed this design more than 500-600W. Add more jiggawatts at your own peril, Doc Brown. Exceeding Xmax a little bit is ok, exceeding Xmech will require new drivers. Hornresp doesn't account for a few things in the excursion graphs, so reality will probably see a fair bit less excursion than the sims show, but better safe than sorry.
Can't get enough SPL with 500W into one of these? Time to build a second one. You're still going to be coming in under a grand, if you go by what I've paid so far. Nothing wrong with headroom
I'm gathering materials to try out your design regardless. I really like the efficiency, as low-power is a real concern with my home design. I had to modify things to sell the idea to the boss. For better or worse, I'm going to build the box as a base for a couch. Actually, the dimensions you give are perfect for a daybed, but I was planning to make the box a bit wider and narrower with the same port length, so as to make the overall piece not as obtrusive in my living room and more consistent with a normal couch. As a side benefit, where I place it, the back will be at the point of the first reflection of my front speakers (the width allows capture of all three), so I can kill a few birds with the one design.
I hope you don't see this as a perversion of your work, but if I can make a tapped horn look nice in a modern living room, maybe I could convince some people that quality and crazy don't have to coincide.
Also--I'm still going to use my other two drivers in a sealed box (but separate). If I can't make them integrate properly, I've got lot's of other uses for them. I'm thinking I need a bunch more...
I've made lots of progress watching the rain refuse to stop for two solid weeks. It's gotta be dry out there for me to cut wood. Can't do that in the house, so I'm at the mercy of the elements
Otherwise, once the wood is cut, I'll probably have the whole thing done in a week.
If you want to try a refold, that's up to you. I just made it so it would be easiest for me to build it. The way I have it folded now, it can't get any wider and still come in at less than three plywood sheets, but making it wider would help the response and sensitivity a bit.
Well, I would have gotten the woodcutting done today, but somebody's circular saw needs that somebody to go out and buy it a new plywood blade. How did I find this out? The hard way, of course.
I got one cut done, and only one - the new saw guide. Used the old two part guide with a perpendicular board for strengthening to make it.
Gee, do you think the blade's warped at all?
Thankfully, this is only the saw guide. I intentionally left scrap in there for when I do the real cut on one of the side panels from this sheet. So, all is not lost on the wood supply side of it yet.
Here's my cutting platform, built from scrap pieces of pressure treated 2x4:
The drill is so powerful it buried the screws halfway to China in there, so I'm not worried about the saw blade hitting them. Will still avoid cutting near where the screws are.
The bad blade. Lasted me through five sheets of this stuff, and five only. Not sure if that's normal, but around here the pickings are slim for saw blades. Will grab a new one tomorrow if I can and get back at this on the weekend. If the weather holds.
New blade in the house. Also grabbed a few last minute things. Another box of screws just in case 200 isn't enough, the straight brackets that will hold the kludge block to the one panel I can't cut to size (they will be removed before the last panel goes on), and a couple plastic scrapers.
Also grabbed a 1" wood boring bit for the Speakon.
Not a cloud in the sky today, so I was out there making sawdust. Unfortunately, I only managed to get two of the three sheets chopped up today. I don't know about you guys, but when I've been out in the sun and I stop sweating, I also stop working in the sun.
Cutting the two biggest panels for this project is hard enough. Doing it when I haven't been able to exercise properly since last June due to knee issues only makes things harder. I need to work on my cardio.
That said, I am pleased to report that 4 of 12 panels are done and they are accurate to +/- 1mm. You know the saying "measure twice, cut once?" I'm a little more OCD than that. I measured 4-5 times for each cut. Took 3 hours that way, but at least I now have panels way more accurate than the last tapped horn had.
Something else I learned - the new "saw guide" is actually less accurate than the two piece metal straightedge. It's bowed 4mm out in the middle. I had to mount a scrap board to it and clamp it down for tension to make it accurate. As a result, I'm going to have to use the two piece on the final sheet. Those cuts have to be as accurate as I can make them, and I don't see any other way to do it. The two piece has one section that's bowed inward by 1mm. That's acceptable, I think. I'll clamp a stiffening board to it, like in the below picture of my new saw guide - should keep it from bowing inward.
One last thing before pictures. The 40 tooth carbide tipped saw blade is the best thing I ever did. Thanks go to lilmike for the suggestion. Way faster than the plywood blade was, and just as clean cutting.
First cut of the day. Much, much better.
One of the big side panels done.
Working on the mouth side. That masking tape was a suggestion by someone to keep the birch layer from chipping. It didn't work. The saw ripped the tape right off the wood. Ah well... I'm not building a work of art, here. I picked this wood because it was cheap, but good quality.
Four pieces done, in their place of final assembly in front of the projector screen. Tomorrow, I hope to be recovered enough to finish off that last panel.