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The Piezo System
Some guitars are equipped with Graph Tech saddles with built in piezo pickups. The pickup
signal is led to the instrument's output jack after it has been amplified by a preamp powered
by a single 9V battery. The preamp is located in the guitar's control cavity and attached to the
piezo/magnetic signal mixing knob (Blender). The preamp enables adjusting the piezo pickup's
output level to the output level of magnetic pickups (for the Blender's centre setting), as well
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as determining the amount of EQ for the piezo pickup. It is achieved by adjusting two small
PR-type controls located on the piezo system's plate. Adjustments should be performed
carefully, using a small screwdriver or a similar tool (fig. 19).
fig. 19
When shipped from the factory, the piezo volume is set up to match the magnetic pickup's
volume. It may require adjustment after changing strings or after changing the height of the
magnetic pickups under the strings.Piezo pickups tend to carry much more high frequencies
compared to magnetic pickups. In some instances, this may lead to signal distortion. In order
to rectify the problem, it is advised to either (fig. 20), decrease the piezo system's output
volume (fig. 21), decrease the amplifier's input gain or adjust its EQ. Signal distortion may be
also caused by an empty battery. In this case, the battery should be replaced immediately,
with attention to correct polarisation. The piezo system's battery is located in a special
compartment placed at the back of the body, next to the control cavity. The guitar's output
jack also functions as a power switch. To prolong battery life, remove the plug from the
output jack when not using your instrument.
Given the fragility of the saddles' construction and
the fact that they are linked to the electronics with
thin wires, it is recommended to use special caution
while replacing strings and intonation and action
adjustments. Use of superfluous force may cause
damage to the piezo system.
Depending on pickup and electronics' configuration,
there are a few different ways of controlling both piezo
and magnetic signals. One of them is described below.
The piezo system is activated by the push-pull
master volume knob. The next knob acts as a piezo
and magnetic signals' mixer (Blender) (fig. 22).
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fig. 20
www.mayones.com
fig. 21
Electric Guitar User's Manual
fig. 22
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