Philips RH521

The RH521 was a stereo amplifier marketed in 1972 by the Philips Corporation. It was a high specification unit and part of their record playing system consisting of the GA212 electronic record deck, and RH407/01Z loudspeakers. The amplifier power output was 30-watts (rms) per channel into 4 Ω loads with harmonic distortion less than (or equal to) 1 %. An interesting feature of this amplifier is the 4-position contour switch that maintains the high and low frequency ends of audio at lower volumes. One can also connect two pairs of loudspeakers for the Philips STEREO 4 surround sound system. As well as bass and treble controls it also has scratch and rumble filters built-in.

The GA212 record deck was designed to surpass DIN 45 500 standards, and has photo-electronic stop switch that is totally silent. It comes with a GP400 magneto-dynamic cartridge (specifications and details are in the following pages). The turntable also has a floating suspension, with hydraulically damped pick-up arm for accurate cueing.

The RH407/01Z loudspeakers have 40-watts (rms) power handling capacity, and each enclosure has a 10-inch woofer, 1-inch tweeter, and 5-inch mid-range, with 800 Hz and 4000 Hz crossover frequencies. The enclosure design is infinite baffle type with 35-litres volume, and dimension 412 mm × 540 mm × 222 mm.