Halcro dm10 Owner's Manual page 6

The variable resistor and capacitor set the
load impedance of the high input impedance
amplifier stage and act to load moving magnet
cartridges.
This configuration forms an active load. The
variable capacitance
capacitance and the load resistance is 1/8
the value of the potentiometer resistance. This
configuration lowers the noise floor at high
frequency, and its attributes are described
below.
The output of the high input impedance
amplifier stage is, as well, fed to a 15Hz 3
order high-pass Bessel filter. This acts as a
"rumble-filter." Following this is the RIAA
equalization stage. The RIAA equalization
adheres to the RIAA specification within
0.25 dB at all frequencies.
sets the load
th
of
rd
The output of this RIAA stage is fed to a low
noise input selector stage, which has a gain of
2. In truth, if a phono input is selected, this gain
can be set to either 1 or 2, depending upon
the gain of the selected phono input. Some
inputs are balanced inputs and one input is a
current input with a load impedance of 51
ohms, for optimal
matching. The equivalent input noise of the
voltage inputs
3.5 nV/sqrt (Hz), and that of the current input
is 13 pA/sqrt (Hz).
The volume control is implemented so as to
include two identical stages in series. This
minimizes output noise.
5
inter-connect load
is approximately