From TalkBass Wiki
My cab has been built by a local furniture hobbyist... (I encourage you to ask around and find someone in your area). Once he has finished the woodwork, I'll do all the finishing, electronics and outfitting. What this project is not: A bargain build. I know that this CAN be done on the cheap. I wanted it to be done correctly and without compromise. In the end, it will cost somewhere between a nice production cab and a boutique build.
The first set of pictures have been provided by the builder, hereto known as "Andy", since that's his name. He supposedly will be posting HIS take on the build on his own online space including commentary. I'll be happy to post that link when and if it comes to me.
http://www.forums.woodnet.net/ubbthreads/showflat.php?Cat=&Number=4517456
1/2" Baltic Birch (cabinet grade) ply, all dadoes are 1/8". All measurements are within 1/32". You can see that the build starts with one side, the front baffle, shelf and the top bracing unit. The top bracing piece (including mid-chamber bottom) are all one piece of wood. The other pieces of bracing are individual.
Three sides...done. Additional side has been added, all but the lower bracing is in place. The pieces are glued in place, Brads are used as a secondary fastener, but I'm not sure how much they actually add to the structure. The only screws that are used are in the back, and that's so I can get in and do what I need to, to go over the seams and prep the interior once in my hands. Andy doesn't use any metal fasteners, and prefers traditional joinery.
The box together without top and bottom. The back is fitted but not attached. The final cab came to me with all screw holes in the back drilled and counter sunk along with pocket-drilled holes so there are no screws in from the top. There are screws and drill holes in the bottom, where they won't show.
Next up: pictures of the build I took earlier today once getting the cab home:
Pieces and parts:
Speakers:
15” Speaker: Eminence 3015LF: [1]
6” Speaker: 18 Sound 4ND410: [2]
Look around before buying. I got my 15” for around 135+ 5 dollars shipping, and the 6” came for 135 shipping included. Like deals should be fairly easy to come by. While there has been plenty of talk of substituting cheaper speakers, I haven’t found a good argument to skimp. You’re building this cab for a reason, so why not do it right.
Some words about electronics:
CROSSOVER:
Originally I had one of the Eminence generic crossovers in this cab. It pretty much sucked. Don't do it. I later tore out the Eminence and put in a CBG crossover, but with all upgraded components. If you're going to do it, do it right. Also, its important to note, that my crossover is NOT the same as the current version listed. My components have slightly different values. Go with the current version...mine is great, but the newest version is slightly more refined.
Here's the original Eminence crossover compared to some of the beefed up spec for the CBG:
And here's the crossover and L pad installed (again!):
Note that it's all a little ratty looking. Its because I'd been in and rewired, ripped out the Em crossover, Later on, I installed a switch for the L-pad too, and now there are even more splices, and crap. its sound and secured, but not beautiful. I'm not losing sleep.
L-Pad:
For those like me doing this for the first time, this is a “loss pad” or an attenuator. You can certainly purchase one that’s a an adjustable pot, but I was just looking to balance the two speakers. The 18 Sound 6” is more sensitive than the 3015LF, so its suggested to “pad” it back by 3db. A quick heads up...the L-Pad resistor array that I build is NOT the same as the one currently spec'ed. It was built previous to the published plans for the CBG crossover/L-Pad, and as such, varies from the one now listed.
My L-pad is 3.5 db, because the values for the two resistor components were a lot neater at 3.5db rather than 3. For others like me, doing this for the first time the L-pad is two resistors, one in series with the speaker, one in parallel. Of course, there’s a pile of sites that have L-pad calculators, but I like the Weber site: [3]
There are also a pile of different sites that have resistor series/parallel calculators to help figure out what resistor values will work best. (What helped me as a noob was to recognize that speakers are resistive devices too, so if you can figure out how impedance works with your cabs in series or parallel, you’ve got it down). Because the R1(Series) value is 2.65 ohms, running 3x8ohm resistors in parallel works perfectly. The R2 (parallel) resistor should be 16.12, so 2x8 ohm resistors in series does the job. Charlie Escher pointed out that 3.5db works out very neatly, and I appreciate his help!
Resistors: 5x 8ohm 50 watt non-inductive. Mouser and Parts Connexion both had good viable parts, the ones from Parts Connexion came out slightly cheaper:
Part# HUNT-016-68515 8.0R / MRC50
Vishay 8 ohm 50w non-inductive resistor
Wire: My wire is 16 gauge 100% copper. Mine came from an automotive store, but only because I couldn’t find any 16 gauge at any local electronics places and I didn’t want to have to mail order for wire. 18 would probably work as well, I notice that my Berg cab has wiring much smaller than 18 and its never given a problem. Larger than 16, and you’re probably going to have trouble soldering some connections.
Here’s my L-pad, done and ready for installation:
-green in lower left is the positive from the crossover.
-green in top center is the positive to the 6” speaker.
-red in the lower right is to the ground.
Further L-pad notes: Keep in mind that resistors work by creating heat, so space them appropriately for the fact that your array may see up to a couple hundred watts. If you're concerned, it's been noted in the 3rd fEarful thread that you can mount your components on an aluminum plate as a heat sink or probably easier, use a few washers under the components to create some air flow. Of course, don't use any sound deadening material over the L-pad or crossover. In a later L-pad I built, I raised the resistors off of the base by using longer mounting screws and using fiber washers between resistors and the board.
Both crossover and L-pad will be mounted on the 'shelf created by the port. Greenboy has suggested that the upper reaches of the cab would be a good place for mounting (the back of the mid-chamber, etc.) as it wouuld shorten wire runs from the input jack plate. I've instead, gone against this good advice because I want to have access to these parts for future 'in case of's. Mine will be divided, with L-pad on the left of the shelf, below the mid-chamber (I'll wire it up through the holes in the bracing with zip ties to keep the wiring solidly in place), and the crossover will be mounted to the right side of the shelf. This will allow me to use some batting on the shelf, directly below the speaker.
Ok...some of you may know that almost a year after I built my 15/6 I also built a 15/Sub. The box was built by another TB'er and I traded for it rather than paying cash. I had a bunch of hardware left over from my other build, and that made things a bit cheaper and the learning curve was certainly less, since I had done most everything for the 15/6 already. Onward to some pictures:
The 15/sub as it arrived in the mail.
Applying some PL-Premium to all internal seams. You can also see that I've glued backings to the handle holes. This will give the screws more to grab and also hopefully deaden any chance of handle vibration and lessen the chance of air leaks.
Another similar shot...you can see I'm going for speed over neatness with the PL.
Taped off, and ready to start doing coats of black paint for baffle and port.
The Input jacks. Both Speakon and 1/4 inch. You can see they're not paralleled laterally. My 15/6 DOES have all four in parallel. When paralleling my cabs, I always run to the 15/6 first, so I didn't feel the need to do all four. You can also see that all the jacks have shrink tubing around them, ready to shrink. Once wired and shrunk, I fill any air space with silicone for total air tightness.
The low pass for the 15-sub. You can see its a very EASY circuit. This one is mounted on a stout piece of ply, and is both trussed down and hot glued in place. All the wires are also secured. As I knew the sub would be pushing a lot of vibration, I didn't want ANY chance of vibration. My wiring is getting slicker and more organized too.
Sub-box lined. A bit more aggressively than my 15/6. That's thick poly batting that's been doubled over and spray glued. Since this is a sub I wanted a bit more damping material in there. I have no complaints about it sounding 'boomy' nice and controlled on the lows.
Low pass, installed on the port shelf. Easy to reach if I need to...but luckily, so far no need.
Duratex coated, Handles installed. speaker in place. Once the Duratex goes on it moves quickly
Corners and grill installed. The grill is the same expanded metal grill from Reliable Hardware as the first cab. You can see that I also have additional grill mounting hardware. I really like the kit that Reliable sells for additional stand off pieces. Well worth it and the grill is solid and not bending or going anywhere. I have more for the original 15/6 but haven't had the occasion to pull it apart.
Front View.
Back View.
back to fEARful
