Owner`s manual
Syncron User manual. Functions description. Mixer Panel and VFD Display.
10
We want the audio signal to fluctuate away from the maximum level
(distortion begins) and away from the minimum level (or
background level), where some noise is present due the nature of
the ICs used in the electronic circuit (all ICs induce noise into the
audio signal).
At the draw, we depict this “safe” level within two discontinue lines.
We have to set the level of input signal so that the signal peaks do
not reach saturation levels and the lower amplitude parts of the
signal are not too near the background noise level.
We have to acknowledge that a professional audio system is a serial
bounded group of professional audio devices and that saturation or
other signal deterioration present in one device will appear
someway or another at the serial bounded following devices.
If we deliver saturated signal from the mixer to the power amplifier
we will not be able to get rid of this saturation whatsoever. The
power amplifier will amplify all what is given and if noise is given
(saturation at mixer), it will be amplified. Naturally, that is bad.
Protection of power amp and speakers.
Power amplifiers and loudspeakers: Current professional power
amplifiers are quite reasonably protected against signal
deterioration and excessive levels and shortcuts. Loudspeakers are
not that well protected, hence a rule or some must be devised to
use the correct speakers with a given power amplifier.
Well, that rule is not a straightforward statement but more of an
understanding of the principles and nature of the audio signal. The
nature of the audio signal refer to the type of music you are playing
and more specifically of its Dynamic Range. The bigger the
Dynamic Range the bigger the power amplifier needed. If the
Dynamic Range of a give audio signal is big, the difference between
the minimum level and maximum level of this audio signal will be
big as well. Therefore, we will need an oversized power amplifier
with enough power to amplify the maximum levels without reaching
the saturation level at the power amplifier (normally, power
amplifiers have red LEDs to let you know when they start
saturating). As a vague rule we can say that Rock and highly
compress music require a power amplifier delivering a power value
slightly bigger than the rated maximum power of the speakers.
However, we recommend the power amplifier rated power be 1.5
times bigger than the rated maximum power of the speakers.
Example: if the power amplifier rated power is 200W RMS at 8, the
rated maximum power of the speakers should be
200x1/1,5=133,4W RMS at 8.
Using the power amplifier: Saturation and input levels.
In order to make the most of your power amplifier you must watch
two things:
1- Set the volume controls in a way that the saturation LED lights up
only occasionally (peaks).
2- Feed the power amplifier with an audio signal of the appropriate
level. What is the appropriate level? Professional Power Amplifiers
are set for an input level of 4 dBu. Do not panic, it is easy to get to
it. 4 dBu is just a fixed measure of the audio signal that
professional audio community uses as reference level, it can be
expressed also in Volts 4dBu equals 1.23 Volt RMS. So to speak, the
Power Amplifier will work at its best if feed with a signal of a level
near the 4 dBu or 1.23 Volt RMS. How do we set this level? Easy,
using the mixer appropriately. Incidentally, the nominal level for a
professional audio mixer is also 4dBu. Therefore, if we set the
master output level of the mixer carefully monitoring the output
level meters (normally LED bars), we will ensure that the level of the
audio signal fed to the Power Amplifier is near 4dBu because the
nominal level of the mixer is 4dBu and we set correctly the output
level or the mixer.
Why we should avoid saturation?
Obvious reasons aside there is a more “material” reason. Saturated
signal can damage your speakers. Although some speakers have
overload protection, a highly saturated signal can deliver D.C. and
this phenomenon can easily shatter your speakers.
Mixer Panel