7
8. Next, experiment with the AC75 or AC150's graphic
equalizer. Begin by setting each of the seven sliders
to their flat “0” center detented position. Then, move
each filter slider in turn as you play your acoustic and
listen to the effect on the tone each of the equalizer
filters makes. For more information, see the “About
Equalization” section on pages 14-15 of this manual.
Again, when you get a graphic equalization setting
that complements your instrument and playing style,
it’s a good idea to write it down for future use.
If you have followed all the steps above and are
still experiencing difficulties, call Samson Technical
Support (1-800-372-6766) between 9 AM and 5 PM
EST.
Using the Channel 1 Tone controls
For enhanced tonal control, Channel 1 features a BASS
and TREBLE control. The Bass frequency control has an
effect on the low-end frequencies around 100Hz and
the TREBLE control has an effect on the frequencies
around 10kHz. Setting the BASS and TREBLE knobs to
“0” (twelve o’clock position) produces a flat frequency
response. To add more lows to the input connected
to Channel 1, raise the BASS control above “0” and to
reduce the low frequency response, lower the BASS
control to a setting below “0”. To add more highs to
the input connected to Channel 1, raise the TREBLE
control above “0” and to reduce the low frequency
response, lower the TREBLE control to a setting below
“0”.
Using the Phase switch
The PHASE switch is used to switch the polarity of the
Acoustic Ribbon’s speaker system. The PHASE switch
can be used in conjunction with the NOTCH FILTER to
remove feedback (see the following section
Setting the
NOTCH FILTER
).
In some instants the speaker system can excite the top
of the acoustic guitar and create a resonance that pro-
duces feedback. By inverting the PHASE of the speaker
system, the chance of producing a resonant frequency
the feedback is greatly reduced. If you hear feedback,
try engaging the PHASE switch. If feedback continues,
try to eliminate it using the NOTCH FILTER.
Setting Up and Using Your Hartke AC75 and
AC150 Acoustic Amplifier
