ISO
Active Member
It is basically variable pitch rotating fan coupled to induction motor. Pitch of the fan blade is controlled by to and fro motion of the speaker coil. Zero pitch no action. positive pitch will push air out and vice versa. Principle is similar to helicopter fan control.
1. Response is from 25 hz to below 1 hz
2. High efficiency at very low frequencies
3. No equalization needed for response to below 1 hz
4. Has enough acoustic output to move an open door .5" between
1 and 5 hz
5. Transient response is near perfect
6. Requires very large enclosure to absorb fan noise
7. Infinite baffle enclosure to prevent front and back wave
cancellation (I use my entire basement of 2000 sq, ft.) The
smaller the back venting is the lower the efficiency (reduced
output)
8. Requires a low pass xover (recommended xover frequency
between 15 and 25 hz @ 18 db per octave (I use Marchand
Electronics rotary woofer controller which provides 200 watts
to pitch the fan blades, built-in adjustable xover from 15 to 25
hz, gain control, adjustable phase and damping.
9. Requires a motor controller to control the speed of the rotating
fan and maintains constant speed when the fan blades are being
pitched. This controller is used to set the speed of the rotary fan
to match the volume of one's room. My room is 29' long x 19'
wide x 11' high cathedral ceiling and I use considerably less
speed than the maximum.
10. The required opening into the room (minimum is 3' x 3') I use
4' x 4'
11. My enclosure is 8' long x 4' high x 4' wide and is braced completely
sealed. All inside surfaces are lined with 6" fiberglass
12. All the electronics; preamps, power amp that pitches the blades,
sources (Dacs, etc.) should have excellent very low frequency
response.
13. Produces very low bass utilizing low pressure (conventional subwoofers
utilize high pressure (cones move back and forth madly to produce
very low bass. The rotary woofer matches the air load (impedance)
Horn enclosures do the same to match impedance, but would require
an enormous enclosure.
14. One needs an additional 120 vac outlet for the fan motor and motor
controller.
1. Response is from 25 hz to below 1 hz
2. High efficiency at very low frequencies
3. No equalization needed for response to below 1 hz
4. Has enough acoustic output to move an open door .5" between
1 and 5 hz
5. Transient response is near perfect
6. Requires very large enclosure to absorb fan noise
7. Infinite baffle enclosure to prevent front and back wave
cancellation (I use my entire basement of 2000 sq, ft.) The
smaller the back venting is the lower the efficiency (reduced
output)
8. Requires a low pass xover (recommended xover frequency
between 15 and 25 hz @ 18 db per octave (I use Marchand
Electronics rotary woofer controller which provides 200 watts
to pitch the fan blades, built-in adjustable xover from 15 to 25
hz, gain control, adjustable phase and damping.
9. Requires a motor controller to control the speed of the rotating
fan and maintains constant speed when the fan blades are being
pitched. This controller is used to set the speed of the rotary fan
to match the volume of one's room. My room is 29' long x 19'
wide x 11' high cathedral ceiling and I use considerably less
speed than the maximum.
10. The required opening into the room (minimum is 3' x 3') I use
4' x 4'
11. My enclosure is 8' long x 4' high x 4' wide and is braced completely
sealed. All inside surfaces are lined with 6" fiberglass
12. All the electronics; preamps, power amp that pitches the blades,
sources (Dacs, etc.) should have excellent very low frequency
response.
13. Produces very low bass utilizing low pressure (conventional subwoofers
utilize high pressure (cones move back and forth madly to produce
very low bass. The rotary woofer matches the air load (impedance)
Horn enclosures do the same to match impedance, but would require
an enormous enclosure.
14. One needs an additional 120 vac outlet for the fan motor and motor
controller.
