DR250 Bass Guitar/PA Speaker
Last Update: 19 July 2005
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One of my friends told me that his son, Adam, had recently taken up bass guitar. Adam wanted some advice on what kind of speakers he should use. Pro sound isn't my thing, but I was fairly certain that the DIY world had something out there that was at least as good as the bargain retail offerings.

I did quite a bit of research, and finally wound up on Bill Fitzmaurice's site. Bill has quite a few folded horn deisgns. I've been intrigued with horns since the 80's when one of my roommates had a pair of Klipsch LaScala's. The idea of an inexpensive, highly efficient bass box made a lot of sense, especially since I had a young, able bodied assistant! After browsing, exchanging emails, I bought plans to Bill's DR250.

The DR250 uses a 10" prosound woofer with an optional tweeter array. After looking through the recommended drivers, I chose an Eminence Beta 10 with 8 piezo tweeters. Construction of the box (as I did it) uses 1/2" baltic birch plywood, 1/8" poplar "bending" plywood, and 3/8" bending luan plywood. We probably had 40 hours into the construction.

The final form is a very impressive speaker for the $170 in components and wood. This is a very articulate PA monitor that could probably run off of 10 watt toy amp. We tried it with one channel of my cheapie 50 watt shop receiver. Neighbors came by to see if they were left out of the party!

As predicted, some equalizing would be necessary for "flat" response. Sounds much better from 20-40 feet away than it does up close. The crossfired piezos are surprisingly good. Somewhat harsh & sibilant up close, but very listenable at longer distances (especially for under $2 each!) It does a great job on vocals & piano. MUCH cleaner than the average DJ rig.

Last, (but not least) is the way cool factor. Adam is looking forward showing up with a one of kind box, that he helped build. I'm looking forward to some future income from his gigs down the road.

Lessons Learned (What I would do differently the next time)

• Cut the pipe in half before building the side braces to the horn. Use the half pipe to determine the optimal width of the wings.
• Cut three trapezoidal inserts for the interior horn to keep it aligned and parallel
• Trim & sand the internal horn before mounting to the box
• Cut top,bottom, & center rounds at the same time
• Mount the center semi-circle braces after covering the sides of the horn
• Move small ports to top, long ports to bottom
• Make the partial braces on the inside of the horn shorter to allow access to the screws on the driver
• Rotate the driver so holes don't line up with the braces for the inner horn
• Move all tweeter holes away from the notch as far as possible
• Do the case of the interior horn out of two layers of 1/8"
• Rivet and glue the inside two pieces of 1/8" plywood together before shoving them into the butt crack
• Preform the 1/8" before bending (let it sit overnight)
• Cut the bending layers at least two inches too long and trim to fit (Bill warns you)