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Design Goals

• Omni-polar Dispersion with a small point source by using closely spaced small drivers
• Very Low Distortion
• Minimal Baffles
• Small Size/Weight and easy to move (for best sound, the these speakers should be placed at least 3 ft from the walls)
• Easy Construction (PVC Pipe)
• Reasonably priced high quality drivers
• Fountek FR88EX 3" Full Range
• Tweeter - Vifa OX20SC00-04
• DSP Active Crossover (Behringer DCX2496) but something like the MiniDSP would also work well.

Photos

Construction

This is a very easy to build speaker. It uses 3" Schedule 40 PVC pipe and a single coupler. The 3" driver is has a few wraps of masking tape to make it a tight fit into the coupler. You could also use silicone to make it permenant.

The tweeter is connected using the black wire from standard 12 Gauge household wiring. The wires are passed through the mounting holes for the 3" driver and secured with silicone and then bent into place. I used crimp on connectors with black heat shrink tubing to cover the connectors.

The grill is made using hardware cloth (wire mesh like uses for small animal cages) and covered with standard grill cloth. I cut two 1/4 in high pieces of of PVC coupler (Warning: To cut, use a miter saw and attach a pipe coupler to a scrap piece of pipe so you can keep your hands at a safe distance from the blade) and hot glued it to the top and about 1.5" from the bottom the hardware cloth. I then covered the top with grill cloth using small dots hot glue in non-visible areas. I then wrapped the cylinder with a piece of grill cloth that extended about 1" past the bottom of the cover. I hot glued it on the back and then tucked the extra cloth on the inside of the grill cover to make a snug fit.

Polar Measurements

Horizontal polar response from 1 meter at 0, 30, 60, 90, 180 degrees (Smoothing Gated response)

the purple line is 180 degrees (1 m behind speaker)

Ignore measurement below 1 Khz

Crossover

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Listening Impressions

• Very low distortion
• Very flat response
• Closer sound stage
• Must be placed at least 3 feet from walls
  • Sounds best to me when listened to a with a 6 ft equilateral triangle (provides a good ratio of direct to reverberant sound)
  • It's very hard to localized the speaker and sounds good anywhere in the room

Another Similar Design

Oliver at 2pi audio independently created a similar design using the same tweeter called the Demokrit-T