Joris and others who build enclosures at home...

Discussion in 'Amps and Cabs [BG]' started by coyoteboy, Jul 26, 2001.

  1. coyoteboy

    coyoteboy easy there, Ned Supporting Member

    Mar 29, 2000
    Sactomato, CA
    This question may have come up in the "cabinet building 101" thread, so I hope I'm not being repetative, but I'm thinking of trying my hand at prototyping and building an enclosure or two for myself. My question is: approximately how many man hours does it take you to build an enclosure, and how much, approximately, does it cost?

    Assuming that you have all the spec's, materials, and tools, and not including the driver(s) which is a large cost variable, and starting from uncut plywood. You can use whatever spec enclosure you'd like.

    I'm not asking those of you who actually sell your cabs to reveal your base construction costs, I'm just trying to get a basis of comparison to conventional enclosure design, as what I'm thinking of trying is not conventional in terms of materials or construction technique.

    Thanks in advance.
  2. I'm not a cab-builder myself, but i think that there is only 1 answer possible to this question...

    it takes just as much time / cash as you want it to.

    e.g. you can buy speakers that cost $30 a piece, but you can also buy speakers that cost $800 a piece..
  3. coyoteboy

    coyoteboy easy there, Ned Supporting Member

    Mar 29, 2000
    Sactomato, CA
    and not including the driver(s) which is a large cost variable,
  4. My last project was pair of cabinets for my 15" subwoofers. I use MDF because it is dense, straight, and easy to make a precision cut. Standard plywood is totally unacceptable. I have no experience with marine, Baltic, or other grades of plywood, but can tell you the sh*t you get from Home Depot is not acceptable.

    $30 (1) 4x8x3/4" sheet of MDF
    $200 (1) Rockford RFR-2215 subwoofer
    $60 handles, grilles, Speakons, jack plate, t-nuts, mounting hardware, port tube, wire
    $5 Titebond III glue
    $16 (2) yards ozite carpet
    $10 3M "77" spray contact adhesive

    Time involved:

    3 hr: measure & precision cut each cabinet panel
    1 hr: measure and cut driver openings and ports
    4 hr: precision cleat all mating panels
    8 hr: gluing, fitting, bracing, and farting around time
    2 hr: port tuning
    1 hr: driver installation and wiring
    1 hr: cut and install handles
    1 hr: cut and install jack plate
    1 hr: route cabinet edges to 12mm radius
    1 hr: seal all internal joints with a bead of RTV

    I use a table saw and circular saw with an 8 foot precision straight edge to make all my cuts. I get better accuracy with the circular saw than I do with the table saw by using a depth micrometer to get exact measurements from the straight edge to the kerf. This is painstakingly slow.

    All my panels are both glued and screwed. Every mating panel has a common cleat that is glued and screwed to one panel. The cabs are cross braced internally with a glued and screwed series of braces. Cabinet edges are rounded with a 12mm / half-inch router bit to prep the edges to accept standard corner pieces.

    I'm not a production cabinet maker, so I don't care about all the time involved. It is irritating for sure, but that is part of the fun. If I calculated the amount of hours building cabinets at my hourly billable rate as a computer consultant, I would be paying a fortune for building the cabinet. However, this is a pleasant exercise that does NOT have anything to do with computers, so I consider it "therapy" and overlook the hours involved.

    After you build your first one, there will be a list of "aw-sh*ts" that you didn't visualize during the design. This is a Normal Thing, and why you should consider your first cabs as prototypes, and don't fool yourself into thinking you are going to build the Mona Lisa your first time out.

    One of things many builders miss, is to recess the speaker board enough to allow for the grille and hardware. One inch is not enough. I recess two inches.

    Have a cabinet shop build it to your specs. This will provide you with instant gratification the first time out.
  5. Nightbass


    May 1, 2001
    Seattle, WA
    Hey, bgavin, let's talk about this some more. Tell us exactly how you use an 8 foot straightedge to make precise cuts - how do you get a 90 deg angle, and how do you clamp it to the plywood?

    I'm thinking that we can open the world of bass cab building to more people if we can present a suitable alternative to the table saw, for patient and meticulous DIYers. A good Makita or whatever is only $125 or so.

    The idea of getting more precise cuts than a table saw is intriguing, so do share...

  6. I use a pair of Central precicion calipers which also has depth gauge are part of the mechanism. I use a couple of cheapie C clamps to bolt the straight edge to the work so it provides an edge to the circular saw. Make a cut on scrap material, then use the calipers to make an accurate measurement from the edge of the cut to the straight edge. Mine is 1.465" or something similar. Write it on the circular saw with a sharpie pen.

    The straight edge itself is just a piece of 5/16" x 2" x 8 foot aluminum stock that I picked up at a hardware store. I got a thicker piece for dimensional stability. You can also use an aluminum level, such as a Craftsman, but they are a bit more difficult to easily clamp to the work. Check the straight edge with an 8 foot level while buying at the hardware store. That way you don't have to own an 8 foot level just to check your straight edge.

    I use a Roofer's square for my 90 degree angles. If you are anal, you can check them by comparing both diagonal measurements. If square, both will be exactly the same. If they deviate, you have an out of square box. If you make that cut, you are f*cked from here on out.

    EVERY piece must be square.

    When you lay out your cuts on MDF, you can get really close by marking the cuts with a razor blade instead of a pencil. This is shaving RCH at this point, and why precision cuts with a circular saw take so much time. It is all in the setup.

    All my joints are butt and cleat type. I use a scrap piece of 3/4" MDF to position the cleat exactly so the mating panel is completely flush. In other words, the cleat is 3/4" from the edge of the butt joint, but since MDF is not exactly 3/4", I use a scrap piece as a jig to accurately locate the cleat.

    If you can layout your panels so that common widths (or lengths) can be made with a single cut on the 8-foot length, you will have more accurate panels. For example, if the box is 20" deep, each top and side panel will be 20" by whatever the other dimension is.
  7. Bgavin, my sentiments exactly.

    I only use a circ. saw for my cuts, and use a long straight edge and clamps to make the cuts.

    What you might want to mention next is how you make your speaker cutouts. I use a scrap piece of 1/4" thick wood. Then I make a hole for the router bit, then bolt it to the scrap wood. Next, I get the radius for the speaker hole. Then, I measure from the outside tip of the router bit I use (1/4") to a point on the scrap wood. I make a small hole for a screw, the hole must be just a "bit" larger than the screw so it can pivot. Then find your center for the speaker, bring the router bit all the way up so the router will fit flush. Then put a screw through the hole on the router-wood combo exactly onto the center. Then I make 3 passes at slightly greater depths. The max penetration of my router will go to exactly the correct depth to cleanly cut through the MDF. Using this method, I've achived precision of +/- 0.06 of an inch. Quick, and precise once you've got your radius found out.

    I ususally use butyl adhesive for gluing it all together. I'll build the cabinet up, then undo one panel at a time, then glue and reassemble. I also use 2x3's for internal bracing on loaded panels (ones with handles, or if it's a bottom cabinet, then put them vertically). I then route over all the edges, then Super 77 the carpet on. I always lay out my designs fully on ProE or ACAD.

    I leave 1" of recess for speakers. This is because I then use rolled expanded metal for the speaker grill. I then do like the new ampegs, and roll the edges over for strength. Now for speaker clearance, I'll hammer and dolly to stretch the metal to make a large radiused "sphere" in front of the speakers. Talk about time consuming, but it's incredible looking. This gives more than enough room.

    It takes a good amount of time. The initial buildup is only half the battle:) Finishing is what takes all the time:)
  8. coyoteboy

    coyoteboy easy there, Ned Supporting Member

    Mar 29, 2000
    Sactomato, CA
    Thanks a bunch, gavin and nuts! your rough guidline will help a bunch I'm sure. After I have a finished product, I'll post it up.

    Thanks again