14
TUBE VITALIZER
The Process Level control determines the ratio between Bass
and Hi-Mid Freq. to the original signal. It also determines the
damping intensity of dominant mid frequencies. This allows rapid
adaptation to the loudness curves (Fletcher-Munson curves,
‘curves of equal loudness’, see below). Practical adjustements
range between 3 to 7.
The human ear perceives the audio frequency spectrum at
varying sound pressure levels very differently. Perception is by no
means ‘linear’. The Tube Vitalizer alters the frequency spectrum in
such a way that the balance is maintained between all frequency
ranges even at varying monitor volumes. For the human ear, the
sound is more pleasant and easier to perceive than the original. In
other words, increasing the Process Level value also increases the
intensity of the Hi-Mid Freq. filter and the Bass filter, whilst domi-
nant mid frequencies are damped by amplitude-controlled phase
shiftings. This improves the perception of loudness, clarity and
the bass punch, i.e. the strength and fullness of the audio signal.
Measurement 5:
Bass = Soft
Bass-LC filter = Active
Hi-Mid Freq. = 3 kHz
Process Level = 0 to 10
Diagram:
Fletcher-Munson curves,
»curves of equal loudness«
Control elements
sound pr
essur
e lev
e
l in dB
threshold of pain
loudness level
frequency in Hertz
thr
eshold of hearing
Process Level
7
