1st Build - Jack 112

[miramadar]

Here's a link to the post leading to the decision to build this speaker:

http://billfitzmaurice.info/forum/viewt ... 28&t=20399

So, I've ordered the drivers from Leland Crooks at speakerhardware.com. I ordered 16 piezo tweeters, an Eminence 3012HO woofer, and a pre-built crossover. The piezos and the crossover came today. The woofer should be here tomorrow.

I'm having a very difficult time finding suitable plywood for this project. I've called every lumber store within 50 miles and there's just none to be had. Locally, birch can only be found in 3/4" and 1/4" thicknesses. The big box stores only carry junk. I did, however, find a lumber store about 1.5 hours south of me. I plan to make a trip down there later this week.

I would like to finish the cabinet in durex, but Speaker Hardware only carries 5-gallon quantities. That's way more than I would use. Does anyone know where to find it in smaller quantities?

Anyway, my journey begins...

[miramadar]

Here's a pic of the crossover... I kinda know what the different parts are...kinda. Ok...not really. I'm more of a wood worker than an electronics guy. Anyway, some advice on how this thing hooks up would be great. This board that Leland made though I of very good quality. Very sturdy construction. There are 2 leads marked "In", two marked "W", and 2 marked "T". I'm assuming that the "In" leads are for the hot and ground from the jack. The "T" are hot/ground to the tweeters, and the "W" are hot/ground to the woofer. Confirmation of this would be great. I really know very little about electronics.

I ordered 16 tweeters. My original plan was to have a 16-tweeter melded array. Since then, though, I've decided that for this cab I'm going to have 8 tweeters mounted flat. If this thing sounds as good as everyone says, it will be the "top" half of my 2xJ112 bass stack. The "prospective" bottom cabinet will be woofer-only. If all goes well, I plan to build another pair of J12's for PA mains, at which time I will use the other piezos.

[miked]

There are 2 leads marked "In", two marked "W", and 2 marked "T". I'm assuming that the "In" leads are for the hot and ground from the jack. The "T" are hot/ground to the tweeters, and the "W" are hot/ground to the woofer. Confirmation of this would be great. I really know very little about electronics.
.

You are correct. I don't have plans for the Jack, but I'm assuming the piezo array is like all the other BFM cabs and is wired out of phase. If the plans say to do so, simply switch the + and - leads from the piezo array. + to - and - to +.

Most decent lumber supply places should have Baltic Birch. They may call it Russian Birch. Essentially, you want 9-ply, 1/2" birch ply. Possibly the guy you spoke to on the phone didn't really know the different names it goes by? Keep trying to get BB; the crap they sell in Lowes or HD is not suitable for cabs.

[Charles Jenkinson]

My tweeters were wired in phase with my woofer. Page 13 of my build thread has the detail. IMO, phase can only be tested with an SPL meter - ears are subjective, meters are not. The convention for woofers is that they should move out when the positive terminal of a 9 volt battery is touched on the positive woofer terminal, and the negative to the negative - wire the woofer for this convention, (and make the assumption at this stage that whatever may be upstream in a P.A. type set up (not your case just for now) that the amp (or amplifier systems) are all in phase.)

[miramadar]

The 3012HO came today! Very cool speaker...and weighs close to nothing! I picked up some maple plywood yesterday...closest thing I could find to birch around here. $50 per 4x8 sheet. I got 4 sheets to make the trip worth it. Should be enough to make 4 Jack12's. I hope to get 1 of these cabinets done over the long holiday weekend. Well, at least put together. I still haven't found a source for Durex coating. The maple plywood looks nice, so I might just stain it and coat it with oil-based polyurethane, satin finish.

[miked]

http://store.acrytech.com/Speaker-Cabinet-Coatings/

Leland carries it too, but his site says roller grade is out of stock. http://www.speakerhardware.com/duratex-roller-grade.php

[LelandCrooks]

Order it direct. I'm out, and will be for a while. I do have pints in stock.

[miramadar]

I got a long way over the long holiday weekend. Here are some pics...

[miramadar]

[miramadar]

[miramadar]

[miramadar]

Thus far I figure I've got about 20 hours on this box. A lot of that time, though, was spent figuring out the best way to do a particular task or finding tools. For instance, it took me a while to figure out how to line up the top/bottom onto the baffle in order to glue it. I decided to use wooden dowels as reference pins. I drilled through the top and into the baffle, installed the dowels, put adhesive on the edge of the baffle and then set the top down on the dowels. That process, figuring it out and actually finding some dowels, took the better part of an hour. Depending on how well this cabinet sounds, I plan to make 3 more Jack12's and it shouldn't take nearly as long.

I found that I spent almost as much time removing glue squeeze-out as I did cutting out the pieces and putting them together. Luckily I have a good paring chisel that works great for this.

Being my first cabinet, and given the fact that my woodworking skills were a bit rusty, I'm pretty satisfied with things overall. There are some mistakes, but I don't think they are critical.

More to come...

[88h88]

It all looks good to me! Like you said, as this is the first time you'll tend to be more careful but the second one will go far quicker as you'll be used to the processes. Keep up the good work!

[iamlowsound]

You could just use regular truck bed liner, Home Depot or Lowes should carry it.

lowsound

[biggerrigger]

A great tip to speed up the PL cleanup is to wait about an hour after you apply the PL then run the chisel down the joints. This gives it enough time to set but not become rock hard. It sure makes clean up go way faster. If you hit a soft spot in the PL and it sticks to your chisel just let it cure and it will peal right off.