September 12, 2011

Point source horn - building my prototype

This is my first attempt at building a point source horn. 

Fitting the parts together. This isn't as easy as you think! They don't all sit flat, so one pair of sides had to be chocked up with wedges before I could drill.


You can see the edges aren't quite perfect, but it was close enough. Each of the four parts had three edges at different angles. Only the front edge could be left square. 

The corners required some figuring out. The pencil marks show my first idea about how to do it, until I realised it would be better to do it differently. I cut it off square further back.

At this point, it hasn't been glued together. I took it apart and used a 13mm round over bit on the front edge. Then the pieces were glued together. The trick was to stop the round over early. This is the result.

Fixed in place, I then cut off some of what remains with a hand saw, then smooth things off with a hand file.

The threads that came with the DE250 aren't long enough, so I had to buy some and then cut them to length. The head of the bolt is under the flange and a cut away had to be made so I could screw it on with a spanner. The bolt head would otherwise hit the wall of the horn. 

I cut the port holes with a spade bit prior to fixing the pieces together, so I could do it with a drill press. It isn't obvious at first, but for the ports to come in at the right place, they have to be drilled through the side walls as shown. It was a bit tricky. A more accurate way to do it would be with a drill press, but I would need to make a rig to hold the horn at the right angle. This is one of those things that turns out to be more difficult than expected. 

Side view with drivers installed. A simple base allows it to sit on top of my subs securely. 

So many drivers, so little space:

Drivers are B&C DE250 and Pyle PDMR5.

1 comment:

  1. Wow, nice job getting all that MDF together and worked so well!
    - ZOG


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