In the fifties
Philips introduced the Bi-ampli system. The radios have
two separate amplifiers. One has high tones filtered out
and is connected to a big speaker, the other one has low
tones filtered out and feeds a smaller speaker. This way
one gets a better sound reproduction, because high and
low frequencies have less chance to interfere with each
other and the total output power is doubled (in theory).
In 1965 the Bi-Ampli logo disappears. This receiver has four wave lengths: long wave (1150-2000
m), medium wave (185-580 m), short wave (16,5-50,8 m)
and FM (87,5-100 MHz). It can produce stereo output from
an external source and therefore has two identical
amplifiers and speakers, but it does not have FM stereo. Plano radios
have a low profile and big tuning dials at the front.
Loudspeakers have moved to the sides.