Fishman SA330x, Руководство пользователя

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About Acoustic Feedback
There are two features to help control acoustic feedback when using the
SA330x with a microphone or acoustic instrument – the Phase switch and the
Anti-Feedback notch control.
Feedback usually occurs when the natural resonances of a microphone or an
instrument react with amplified sound. The louder these sounds are amplified,
the more they can interact. Feedback occurs when a sound resonates in sync
with the amplified sound, reinforcing and building to a sustained howl.
Phase Switch – The Phase switch flips the polarity of the input signal from
positive to negative, changing its relationship to the sound coming from the
amplifier. One phase setting usually provides better resistance to feedback
than the other and will vary depending on the input source or instrument and
the playing environment. Another approach to determining optimal phase
is choosing the switch position that sounds or feels most natural. In certain
environments the Phase switch may not have an audible impact.
The Phase switch also affects the signal polarity to the balanced D.I. and
Monitor outputs, synchronizing the amplifier with other sound systems in use.
Anti-Feedback - The Anti-Feedback control is a variable frequency notch
filter designed to subdue a resonant peak of a sound source that might be
prone to feedback. Turning this knob adjusts the center frequency of the filter,
ranging from subsonic (off) to 330Hz at full clockwise. To adjust this feature, try
to induce feedback and then turn the control until the intensity is diminished.
Setting Phase and Anti-Feedback
1. Start with the Anti-Feedback control turned down completely.
2. Turn up the Volume and or Gain on the SA330x until feedback begins.
3. Flip between the two Phase positions. Each position will produce a
different dominant feedback frequency. Listen to the frequencies and
select the Phase position which allows the higher note to feedback while
subduing the lower.
4. Adjust the Anti-Feedback knob clockwise until it subdues the frequency of
the higher feedback note.
Since optimal tone is a matter of taste, one can also experiment with reversing
the order, using the Phase switch to control the upper feedback note and the
Anti-Feedback notch for the lower.