FSG-01 First Stage Gain Control Daughterboard
for System 1000™
The FSG-01 is a First Stage Gain control daughterboard for the
MDA-101,
a System 1000 microphone preamplifier - line level DA. The FSG-01
performs gain change directly at the input stage of the microphone
preamp thereby optimizing the noise and distortion performance of the
preamp. By placing the actual gain change at the first stage of a
microphone preamplifier, the noise figure and distortion performance of
the preamp is maintained. VCA gain control is often placed in the third
stage of a preamp, however this is a compromise to overall distortion
and noise performance as well as making first stage clip condition
correction impossible without a remote input attenuator.
The FSG-01 uses 8 ultra miniature relays to select 9 different
gain settings for the first stage of a preamp. The gain range provided
is +25 to +65 dB inclusive, in 5 dB steps. Control for the daughterboard
is performed by way of a DC input voltage with a range of 0 to 10 volts,
either positive or negative going, where 0 volts represents 25 dB of
gain and 10 volts represents 65 dB of gain. By using the remote input
attenuator option on the MDA-101, a total gain control range of +5 to
+65 dB is achieved. The control port input to the daughterboard is a
differential amplifier which facilitates noise free control over long
distances.
The FSG-01 remote controller can be as simple as a single 1
k ohm potentiometer placed between ground and a single +10 volt
power supply, or as sophisticated as a full computer control system
feeding the output of a simple 8-bit DAC to the control port input. An
easy control implementation is accomplished with a 9 position switch and
a resistive voltage divider network. All logic on the daughterboard is
static, that is, there is no clock signal on the board that would
compromise the operating signal to noise ratio.
LEDs on the front edge of the daughterboard provide a visual
indication of the gain taken in the mic-preamp.
Price: $230.00 Product has been discontinued.
Larger image of FSG-01
FSG-01 Manual
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