So very rare to find in great working condition .  *SOLD*

The RH532 Electronic MFB is an electronic three-way loudspeaker enclosure employing the Philips motional feedback system.

This box, having a volume of 15 litres, incorporates three special loudspeakers, an electronic regulator and control system and two power amplifiers with a total output of 60 Watts (sine wave) – a 40 watt amplifier for the low notes loudspeaker with MFB and a 20 watt amplifier for the middle and high notes loudspeakers.

Incorporated in the cone center of the low notes loudspeaker is a piezoelectric element (PXE) which monitors the cone acceleration and converts it into an electrical voltage. This voltage is proportional to the cone acceleration and is led into a comparator circuit where it is accurately compared with the original signal supplied to the loudspeaker by the amplifier.

Cone movement does not always accurately correspond to the electrical signal applied to the voice coil. This is due mainly to lack of uniformity of the magnetic field coupling with the coil during large cone excursions and resonances of the cone and of the air enclosed by the loudspeaker box. These effects are particularly apparent in the low frequency region and result in distorted bass reproduction.

The voltage difference. detected by the comparator, is fed back to the loudspeaker via the amplifier as a correction signal, thus the loudspeaker is forced to reproduce the original signal.

Specifications

Type: 3 way, 3 driver loudspeaker system

Frequency Response: 30Hz to 20kHz

Crossover Frequency: 500, 3500Hz

Bass: 1 x 8″ AD8065

Midrange: 1 x 5″ AD5060

Tweeter: 1 x 1″ AD0160T

Enclosure: 15 litre

Dimensions: 378 x 283 x 212mm

Weight: 12kg

Note: built in amplifiers