Blaupunkt CASABLANCA Casablanca CD51 Operating Instructions Manual page 27

Start by adjusting the treble and mid levels and finish by setting the bass levels.
Sound Impression / problem
Bass too weak
Dirty bass,
booming sound,
unpleasant pressure
Sound very much in the foreground,
aggressive, no stereo effect
Dull sound,
low clarity,
no brilliance to the instruments
Measures
Increase bass
frequency: 50 to 100 Hz;
Level: +4 to +6
Reduce the lower mid level
frequency: 125 to 400 Hz;
Level: approx. -4
Reduce the mid level
frequency: 1,000 to 2,500 Hz;
Level -4 to -6
Increase the treble level
frequency: approx. 12,500 Hz;
Level +2 to +4
53