The RiPole 30 is a special dipole variety. This subwoofer design - patented by Axel Ridtahler - doesn't increase the woofer's resonance frequency (in free air it's at around 27 Hz), on the contrary, the resonance frequency of the mounted bass driver is reduced to 20.7 Hz.
The theoretical background was provided by Siegfried Linkwitz who designed similar dipoles.
The subwoofer requires a specific type of bass driver, e.g. the RBS 512, chosen by Axel Ridtahler.
Our listening impression:
The RiPol 30 is not well suited for high volume sound reproduction. On the other hand, for those who want low bass that is unobtrusive and freely floats through the room and cannot be located, the RiPol 30 is the answer. This loudspeaker is the perfect choice for: - PC home cinema - bass that may not be located - bass extension for electrostatic and full range drivers.
The RiPol 30's disadvantage is that for high volume levels several loudspeakers need to be stacked.
The picture to the right shows the RiPol 30's frequency response (measured in 1 metre distance, speaker away from walls). According to our taste this is the ideal position. For those who prefer even lower bass the amplifier module Detonation DT 80 may be adjusted (a) at 30 Hz by +3 dB (b) or at 25 Hz by +6 dB.
The RCA amplifier module Detonation DT 80 was chosen for its abundant adjustments. The module is placed in a separate casing, sized 314 x 264 x 154 mm and provides extremely neutral bass coming from a small loudspeaker enclosure but also allows adjustments according to taste.
Price of standard kit with amplifier module: - not available
further details about the bass driver
Hint: For a genuine hi-fi system we suggest two RiPoles that should not be placed in a corner or close to the wall.
RiPol 30 Building Instruction Home
For higher output levels several RiPoles may be stacked.
Slightly modified components and a more powerful Detonation DT 150 are being used.
Price for Twin RiPole kit R30-2 with amplifier module DT 150: - not available
Axel Ridtahler's comparison of different subwoofer systems you'll find here