It 'compensates' for the drop off of hearing in frequency extremes when the volume is lowered.
Unfortunately the compensation is a fixed one (probably about 20db at 20Hz and 4db at 16kHz) and not much use for accurate compensation.
Nakamichi and Yamaha had variable compensation controls on their pre-amps of the '70s, which compensated by reducing the volume at the mid frequencies only, thus being a more accurate compensation from the normal (flat) volume level.
Bob P.
Unfortunately the compensation is a fixed one (probably about 20db at 20Hz and 4db at 16kHz) and not much use for accurate compensation.
Nakamichi and Yamaha had variable compensation controls on their pre-amps of the '70s, which compensated by reducing the volume at the mid frequencies only, thus being a more accurate compensation from the normal (flat) volume level.
Bob P.