IPAL (Integrated Powered Adaptive Loudspeaker)
The IPAL principle maximises the efficiency of
Traditional transducer design is compromised by the need to present an amplifier with a load impedance that is as resistive as possible – which implies a loss of efficiency of the transducer and also sets a limit on the current in the voice coil because of thermal dissipation. A transducer that would minimise the voice coil resistance, maximise the Bl “force factor”, or that would present a more reactive load, would enable a significant increase in the conversion efficiency.
In the practical embodiment of the IPAL principle in the ASX, DSP controlled, active feedback topology “emulates” an ideal virtual “target” transducer to maximise efficiency and maintain linearity at maximum excursion. Distortion is reduced by up to 20dB and power compression virtually eliminated. The IPAL system in the ASX comprises a dedicated Class D amplifier module, a DSP system,
a 21" (530mm) transducer unlike any other and a differential pressure sensor.
the drive unit
A neodymium motor system of immense proportions, coupled with a voice coil impedance of less than one ohm enables the drive unit to generate an unprecedented force upon the air load presented by the enclosure. This ability dominates the rest of the driver’s
By adjusting the processing in the control loop, fixed parameters such as moving mass, resonant frequency and even cone area can be “virtually” adjusted and optimised.
To handle the unprecedented forces and resultant air pressures requires an extremely strong cone material. Made from a mix of cellulose and carbon fibres, the cone has excellent strength when in tension and compression – unlike woven aramid fibre cones, whose compressive strength is much lower than their tensile capabilities.
amplification and DSP
The efficient Class D amplifier topology in the ASX is capable of delivering a peak power of 8.5kW and dramatically reduces the amount of energy dissipated as heat, as well as being much smaller and lighter than other amplifier topologies. The switchmode power supply, with Power Factor Correction for worldwide operation, has very high voltage rails which can also provide high levels of current into the very low impedance of the 21" (530mm) drive unit.
The DSP system is programmed with a number of parameters which represent the model of the ideal “target” loudspeaker. The actual audio input signal is then processed, so that the real loudspeaker emulates this ideal target at all power levels. A differential pressure sensor is mounted close to the transducer and is part of a feedback loop which generates an error signal feeding the DSP system to compensate for the
*International Patents PCT/IT2006/00615, PCT/IT98/00031.
US Patent No. US 6,281,767 B1
commercial installation: ASX © Martin Audio Ltd.
