October 2, 2011

S2 prototype - construction 2

More progress on my second point source prototype. 

Tools I couldn't do without:

You see two sets of calipers. The top set find the dimensions of the throat, which can then be measured with the calipers. There is also an angle tool which gets used a lot with a project like this. 

This is a "buzzer." It's a fixed plane with a fence that can be angled. It's good for planing down rough timber edges quickly, but it can also do angles. Most of the angles for the horn were done on the buzzer. 

Shop smith. It's a multi-purpose tool - table saw, drill press, wood lathe and sanding disc all in one. In this project it functions mostly as a table saw, few of the angles are best done with this tool. 

You may have noticed the throat has some interesting things going on. This is where it gets fixed. The table on the shop smith is angled as shown and the horn is clamped on. See below. Now the sanding disc is pressed into the throat until it comes out nice and flat. 

Like this:

With the different angles involved here, I need a different mounting system. A flange will mount to the horn, then an acrylic sheet makes it all work. You can't attach the compression driver to the flange as the drivers are in the way. 

The flange and mounting plates are fixed together and then I find the centre point, marked with a punch. You can see the holes in the acrylic sheet already drilled. 

A very large drill bit comes in handy:

The second flare section is a little more difficult to get right. Parts are screwed together so that I can see they will fit together. It's not possible to hold them together correctly, not even with two people.  

Four pieces assembled with screws:

Blocks were used in the corners to help with alignment. The edges of these were precisely angled. 

Second flare angle sitting on top to check alignment:

The horn is bigger than it might appear. Overall width is around one metre!


  1. I did not get a sense of scale until that last photo with your feet.

    That horn is HUGE!!!

  2. Yep, that's why I put the feet in there! Will be mounted in a 1.2m wide bass trap.


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