Integrated Amplifier
SIA2-150
4.1 Description
The SIA2-150 is a high quality integrated amplifier designed to partner ATC passive
monitors and other Loudspeaker systems. It incorporates five line level stereo inputs
plus headphone jack, stereo record, pre and sub outputs on RCA phono sockets and
one pair of loudspeaker outputs.
Input selection is achieved via a rotary control. Output volume adjustment is achieved
by a precision potentiometer. A tape monitor function is a duplicate of the source
selected by the input selector. A standby function is also accessible from a front panel
push button. Mains power is applied from a rear panel mounted switch.
The SIA2-150 incorporates the same gain reduction and loudspeaker protection
circuits as used in the ATC active monitors. This ensures that even working at very high
levels the amplifier is held back from clipping so improving the subjective performance
and protecting the loudspeakers from damage.
All SIA2-150 functions are duplicated on the included ATC SCAR-B remote control
handset.
4.2 Inputs
The SIA2-150 accepts unbalanced RCA phono input plugs. The signal is present on
the centre conductor of an unbalanced input and the signal return is made via the
screened outer. If there is any hum present on the inputs, this must be traced to its
source and not suppressed by the removal of screens or earths. Removal of the
screen on an unbalanced input is likely to result in uncontrollably loud hum. The input
sockets are illustrated in diagram 1.
All inputs are line level sensitivity via RCA phono connectors on the rear panel.
Inputs are labeled CD, Tuner, AV, Aux., and Tape. in. However, they are electrically
identical and a line level signal from any source equipment may be connected to any
input.
4.3 Outputs
The SIA2-150 rear panel, illustrated in diagram 1,
carries connectors for left and right loudspeakers,
Tape left and right outputs, Preamplifier left and
right outputs and a left and right summed mono
output.
Loudspeaker connections are made using the two
pairs of proprietary ATC loudspeaker terminals.
The positive terminal is coloured red and the
negative terminal is coloured black. The left and
right channels are clearly marked and correspond
to the left and right inputs. The wire used for the
connections to the monitors will have some
identification for the positive conductor. Usually
this is red, but may be a moulded stripe on the
insulation.
Diagram 1 - SIA2-150 rear panel and connectors
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