Simaudio 810LP Phono Preamplifier - Manual (Page 10)

810LP Reference Dual-Mono Phono Preamplifier
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10
Resistance Loading:
There are sixty-four (64) unique resistance loading
settings available using DIP switches 1 through 6,
located at the bottom of the upper DIP switch bank.
The range of available settings starts at 12.1 Ω and
ends at 47k Ω:
Figure 3: Left and right channel DIP switches for resistance loading adjustments
The factory default is 47K Ω, whereby DIP switches
6, 5, 4, 3, 2 and 1 are all in the right (‘OFF’) position
as seen in the example to the right. This setting
would be applicable for most moving
magnet cartridges.
When you are using a moving coil cartridge, you will
most likely want to set the resistance loading to a
much lower impedance value. For instance, when
your cartridge manufacturer recommends a value of
100
Ω, you would position DIP switch 3 to the left
(‘ON’) and the other remaining switches (1, 2, 4, 5 &
6) to the right position (‘OFF’) as seen in
the example to the right. We strongly
recommended that you never use the
47k Ω resistive load setting for moving coil
cartridges.
A comprehensive diagram of the DIP switch
combinations for all 64 available resistance loading
settings can be seen on the bottom panel,
immediately to the right of the switches and just
below the previously mentioned capacitance settings
diagram. Finally, the values written beside the DIP
switch number represent the resistance load if only
that switch is in the left position (‘ON’). For example,
when only switch 1 is in the left position (‘ON’), the
load value will be 22
Ω; when only switch 4 is in the
left position (‘ON’), the load value will be 221 Ω; and
finally when only switch 6 is in the left position
(‘ON’), the load value will be 1000
Ω.
Note: Choosing a loading impedance for a moving
coil cartridge is not an exact science as there are
many variables that can affect the manufacturer’s
recommended setting. Choosing the best impedance
is ultimately a compromise between what sounds
best to your own ears and what works best for the
cartridge, based on its internal workings. When
experimenting with different impedance settings,
always keep in mind that a poorly loaded moving
coil cartridge will result in sonic performance yielding
a lack of definition, reduced bass performance, as
well as aggressive upper-mid and high frequencies.