Solidyne AUDIMAX 362, User Manual

Page: 9 / 19

SOLIDYNE
AUDIMAX 362
Pág. 9
2.2.2 Blocks Diagram
1.2 Processing Stages
Stage 1 – Peak Asymmetry Canceller
It is known that, by a particularity disposition of
the vocal cords, the sonorous emission that these
generate are asymmetric triangular pulses. The
three cavities that filter and shape these formants,
to obtain the vocal sounds, do not modify this
intrinsic characteristic of the human voice. All the
spoken word and still sung is strongly asymmetric.
This creates an important reduction of the energy
of the audio signal, particularly when it pass
through a compressor, because the compressor
sets its compression level for the greater peak,
does not concern its polarity. In this way, when a
polarity is fit to the 100%, the opposite polarity
hardly surpasses 50%, due to the asymmetry.
The fact that the music sounds louder than the
human voice, after pass through a compressor is
a phenomenon well known. This is because the
musical sounds are symmetrical, whereas the
human voice is not.
In order to correct this problem, WITHOUT
INTRODUCING ANY ALTERATION AT THE
SOUND QUALITY, peak asymmetry canceller is
used.
This technique, based in a discovery of the Dr
Leonard Kahn, acquires international validity with
the work of Oscar Bonello, published at the
Journal of AES, Vol.24,5 in which it is described,
for the first time, the theory of its operation.
The peak asymmetry canceller is in essence an
all-pass network, a class of not minimum phase
network. That is: a network whose transference
function has zeros in the right semi plane. This
network has a full flat response to frequency; only
its phase response is function of the frequency.
This phase rotation, which must compliment very
particular conditions, is responsible of the peak
symmetry of the audio signals. Signals that by
their nature are symmetrical (like most of the
musical instruments), are not modified by this
processor.
This processor, by itself, allows to increase
between 3 and 5 dB the final power broadcast by
your transmitter (it is to say that it increases by a
factor of TWO the average power transmitted).
Numerous tests have been made in different
countries, to verify, in real conditions, these
results.
Stage 2 – Input Expander
The expander, previous to the compression
process, is an excellent resource to increase the
signal/noise ratio of the original program. This is
advisable, since the compression process, when