Build your own open-baffle loudspeaker system
In the pages listed below you will find information for building open-baffle loudspeakers using conventional cone type dynamic drivers. As an example and as an enticement to you, I provide you with design information for the PHOENIX, a loudspeaker system of the highest sonic performance, true to the original , FAQ22 .
The speaker evolved over a number of years and represents
a departure from my earlier approach to system design in Ref.12.
At that time I had not sufficiently understood the influence of the room upon
the reproduced sound at low frequencies. The speaker is a refinement of the compact
dipole in Ref.
2, a 3-way system with line-level crossover and equalization circuitry ahead of
the power amplifiers.
Each playback channel consist of:
1 - A panel with two 8 inch drivers and a 1 inch dome tweeter. It is an open baffle design and the unit might mount on a speaker stand or hang on two thin ropes from the ceiling to bring the tweeter to ear height or slightly above. The panel should have a distance of at least 2.5 ft (0.75 m) to any adjacent wall.
2 - A woofer with two 12 inch drivers arranged for dipole radiation. The woofer should be positioned at the same distance from the listening place as is the panel, and preferably along the side wall, for optimal summation of sound outputs in the crossover frequency range, and minimal excitation of room modes.
3 - An active crossover/equalizer for three power amplifiers of 50-200 W each. The amplifiers must have identical voltage gains, <0.1% distortion and >20 damping factor.
I have kept the wood working aspects of the design as simple as possible without compromising the sound, and a blank circuit board for the crossover/eq electronics is available. This still leaves to you the details of how to mount the panels, load and package the circuit board, and refine the looks of the speaker. I assume you have available at least a few electronic measurement tools, like a signal source and an oscilloscope, and maybe a loudspeaker measurement software package with a sound card and a measurement microphone. Should you have no access to test equipment, then you might want to have me check your assembled printed circuit boards for a nominal fee. No acoustic tests are necessary, other than for driver polarity with a battery.
Since this is an open baffle, bi-directionally radiating dipole speaker, it is free of the typical box coloration and provides the most natural bass reproduction due to minimal excitation of room modes. Also, as a fully active system and with a superb - but costly - driver complement, it will be capable of extremely dynamic and articulate sound reproduction. It is definitely at the leading edge of speaker-room-listener system design.
The PHOENIX system challenges most other speakers for accuracy of sound reproduction. The theory behind the design may also be a challenge to your understanding of acoustics, electronics and loudspeaker construction. Building the speaker, though, should be straight forward when you follow the detailed information provided and will guarantee a successful outcome.
This is meant to be a DIY project for the music loving hobbyist. Should you consider using part or the whole of my design for commercial purposes, then contact me for permission and contractual agreement before using any of the information provided.