Symetrix 528 - Use Wide Peaks, Narrow Notches; Tuning the Eq;Notch Filter; Parametric Eq;Notch Filter Examples

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If levels are too low, increase the preamp gain (or the output gain of the
device feeding the line input).
4.2.2 ICnow What You Are Liatening To Low frequency boost may increase
the level of some frequencies that cannot be heard, for one reason or
another. Many high quality microphones are capable of generating
substantial output at very low frequencies (below S0Hz) which cannot be
adequately reproduced by most monitor speakers or headphones. Be aware
that the true effects of low frequency boost may not be audible , and may
actually result in a "muddy" or distorted sound.
4.2.3 Uae Wide Peaka, Narrow Notchea In general, the human ear prefer s
wide bandwidth peaks and narrow bandwidth notches . Boosting a narrow
bandwidth produces a sound usually perceived as "offensive ," while boosting
wider bandwidths (. 72 octave or greater) usually results in a sound deemed
"musical." It has also been observed that very few people will notice
anything's missing when a narrow bandwidth (.3 octave or less) is cut,
even when it's cut as much as 30dB . But, cut a wide bandwidth and the
resulting sound quality is often called "empty ."
4.2.4 Tunina the EQ /N o tch Filter To "tune" the equalizer, use full boost .
For both boost and cut, the 528 ' s parametric equalizer / notch filter is
intended to be put to work on specific frequencies . To find fl particular
frequency "by ear' ' (the method used by everyone who doesn 't have a real -
time analyzer); tum the cut / boost control all the way up to +lSdB (be very
careful of feedback if you are monitoring on a loudspeaker!) . Set the
bandwidth for about .3 octave . Tune the frequency control until you
distinctly bear the part of the sound you wish to control. Then, adjust the
cut/boost control for the appropriate amount of change , and readjust the
bandwidth control if necessary.
To notch out interference like 60Hz bum, follow the procedure above to get
an approximate setting for the frequency control. Then, to fine tune the
notch for the best possible rejection of the interference, turn the cut / boost
control all the way down to -30dB. Very carefully adjust the frequency
control for minimum hum. Then reduce the bandwidth to about .2 octave,
and readjust the frequency control for minimum hum. Repeat this process
until the narrowest possible bandwidth is acheived .
4.2.5 Parametric EQ/N o tch Filter Examples The parametric equalizer / notch
filter can be made to behave like many different kinds of equalizer, and to
perform many filter functions. The following examples show a group of
representative frequency vs . amplitude curves, the control settings that
produced them , and in some cases suggested uses for the type of curve
shown.
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