INPUT
– The GBE-100 is equipped with a standard ¼” unbalanced input. Input sensitivity can be
switched from approximately 300 mV (passive) to 1.25 volt (active). The input impedance is 500 k
ohms. The precision input scaling preamp contains a 36 Hz, 12 dB/octave high pass filter (more
effective and less intrusive than the more common 6 dB filters) and an “RFI” filter (radio frequency
interference) to eliminate unwanted noise. The input gain stage consists of a feedback type circuit
that provides continuous variable gain control with minimal noise.
ACTIVE/PASSIVE SWITCH -
This switch sets the input sensitivity for either passive or active
(battery powered) basses. The Active position reduces the input sensitivity by approx. -10db.
GAIN CONTROL –
This continuous variable control adjusts the input signal to the preamp. Use this
in conjunction with the input O/L LED.
O/L LED
– This LED indicates OVERLOAD (clipping) of the input signal. For the cleanest input signal
possible this LED should only light with the strongest peaks from the instrument.
TUNER OUPUT
– The GBE-100 is equipped with a parallel and fully isolated tuner output. Within the
amplifier design this jack is located after the front end scaling preamplifier, is pre-signal shape
and pre-eq and may also be used to drive a separate direct box or high impedance recording
device.
CONTOUR CONTROL
– The GBE-100 is equipped with a variable “contour” control that provides a
wide bandwidth mid-scoop style filter in the signal path. With the control in the counter-clockwise
position, the filter is effectively removed from the signal path.
ACTIVE EQUALIZATION
– The GBE-100 contains an active 3 band active equalizer with sweep
frequency midrange. This equalizer, similar to those found on professional sound consoles, is a
very useful tool. The low frequency eq section is a 100 Hz, shelving curve with 15dB of cut or
boost. The high frequency eq section is a 3.5 kHz, shelving curve with 15dB of cut or boost The
“sweep mid” section features 12 dB of cut or boost with a bandwidth approximately 1 octave wide.
The center frequency of this filter is continuously user adjustable from 150 Hz to 2 kHz with a
single control. This filter is typically (but not always) used to reduce or remove offending
frequencies in the instrument’s pick-up response, or boosting response to achieve a particular
voicing. Spend some time experimenting so that the process becomes creative as well as
corrective.
MASTER VOLUME
– The master volume control adjusts the overall volume of the amplifier and the
effects return. Typically, best results are obtained when this control is operated between the 9:00
and 3:00 positions.
HEADPHONE OUTPUT
- Use this jack to connect standard headphones (8-600 ohms). A speaker
switch on the back panel shuts off the internal speaker of the combo, allowing private practice or
studio work. This output is short circuit protected.
DIRECT OUTPUTS
– The GBE-100 is equipped with a high quality pre-eq. balanced direct output
with a ground lift switch for pin 1. The output level is –10dB nominal line level, pin 2 hot, and the
output impedance is 600 ohm. The direct output is fully protected from mixers providing phantom
power up to 48 volts.
CD/TAPE INPUT
– This line level input allows a buffered connection for a CD or Tape player for
practice sessions or band rehearsals.
