Jun 11 2018

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PB 18

PB 18

Ported Bass 18″

Designed by Mike Hatt of Ivan Sound.

Fusion 360 modeling by Ulan McKnight of LBH Sound.

This file is free to use in any way that you see fit. It would be nice if you shared any modifications/upgrades/insights with the community but there is no requirement to do so.

The .zip file with everything you need:



Design notes:

The PB 18 (Ported Bass 18″) has been specifically designed for the Beyma 18PWB1000FE. Mike’s goal was to produce 30hz is a compact box. While you can use any 18″ driver in this box, the cabinet has been designed to highlight the special features of the Beyma. Please consider purchasing drivers from US Speaker. Al has been a fantastic resource throughout the development of our cabinets.

Handles have been added to the side for easy lifting. The cabinet, including driver and hardware, should not weight more than 65lbs. Four caster supports are included in the design if you wish to attach casters to the back of the box for even easier transport.

We use jack plates to attach a pair of NL8 connectors and a speaker cup (for “bare wire” hook-ups) to get signal to the box. This allows us to run a single NL8 cable from our amps to our “stack” of speakers. From there, we use 4 foot NL8 jumper cables from one speaker to the next. We include an extra “bare wire” connector on our subs (like the PB18) and our lows in case we are in a situation where we don’t have NL8 cable (gotta be ready for anything ;). It is more difficult to damage a sub or low driver so if someone sends high frequencies to the box, it will just sound bad… but the signal shouldn’t damage the driver. (We specifically do NOT include “bare wire” connections for our mid and high boxes.)

Our wiring for the 8 conductors in the NL8 cable are as follows:

1-/1+ sub
2-/2+ low
3-/3+ mid
4-/4+ high

The cabinet dimensions are

22.5 wide
25 tall
31.5 deep

CAD notes:

A single PB18 requires more than one sheet of 4×8 plywood. Two cabinets can be created out of three sheets of plywood and since I normally make two at a time, the first three sheets are for the normal double assembly.

I strongly suggest folks cut a single box to test everything out and make sure the file works on your system. To assist with this, I have included sheets 4 and 5 that will supply you with all the parts you need for a single box. (How sweet =)

The front baffle extends to the bottom of the port ceiling to hide the end-grain of the port. If you wish to hide the front end grain, the rectangle is 22.5 x 25 by the depth of your material.

All bracing, including the port, is secured using pockets. This allows for simple alignment of the parts and holds everything together firmly.

All edges are butt-joints so you can show off your carpenty skills. I had pre-drilled a number of holes in earlier designs but found them to be redundant and didn’t really save all that much time in the build.

CAM notes:

1) Score all parts

We use a .23″ flat downspiral to score all parts. The downspiral bit will push the wood down and limit tear-out. We use a relatively small bit and spin it fast (18,000 rpm). You can experiment with the speed and feed and let us know if you find better settings for the material you use. We do not score the pockets in the interest of time.

2) 2D pocket

We use a 3/8″ upspiral to ensure that the bottom of the pocket is as clean as it can be. We have found the tear-out to be acceptable with the material we are using (baltic birch) but if you are having issues, you can simply add the pockets to the scoring in the first step.

3) Rough climb

This step is the secret sauce. We can power through cutting out the vast majority of material using a 1/2″ downspiral bit. The trick here is to leave an ‘onion skin’ of .1 inch to hold all the pieces together.

4) Onion cut

We use a tiny 1/8″ upspiral to slice off the last material. The upspiral ensure that the bottom face has minimal tear-out. Using a small bit really helps with this.

Permanent link to this article: http://lbhsound.com/wp/pb-18/

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