REAR PANEL CONNECTIONS AND CONTROLS continued
For a single pair of 4 ohm or 8 ohm speakers the Load Impedance switch may be set to its 4-8
Ohms position. The Load Impedance Switch must be set to 2-3 ohms whenever the load will be
lower than 4 ohms. Speaker loads below 4 ohms impedance can cause the Model 275 to over-
heat rapidly and cause audible distortion. These are examples that require the 2-3 ohms setting.
1. Driving two pairs of speakers whose impedances you don’t know.
2. Driving two pairs of speakers with impedances that are lower than 8 ohms. Two pairs of 4
ohm speakers driven simultaneously are a 2 ohm load.
3. Driving a single 4 ohm speaker bridged to mono. This is a 2 ohm load.
4. Driving two 8 ohm speakers bridged to mono. This is a 2 ohm load.
Note:
For the coolest possible operating temperature we recommend setting the Load
Impedance switch to 2-3 ohms even if you are using a single pair of 8 ohm speakers.
Automatic Turn On and Off
Auto Turn On Switch
For convenience, there are two ways the Model 275 can be triggered to turn on automatically.
•
When a suitable voltage is applied to its 12V In (input) jack.
•
When an audio signal is present at the L and R audio Input jacks.
Note:
When either automatic turn on method is selected the Model 275 front panel Power but-
ton is disabled so that on/off is determined solely by the triggering preamp or system controller.
12V Position
When the Auto Turn On switch is set to its 12V position, the Model 275 is turned on and off
with an ex9V to +12V voltage from your preamp or controller. When the external volt-
age ceases the Model 275 will turn off immediately. The 12V switch position disables the front
panel Power button.
Man (Manual) Position
When the Auto Turn On switch is in its MAN (manual) position, the auto turn on function is disabled
and the Model 275 must be turned on and off manually with the Power button on its front panel.
Audio Position
When the Auto Turn On switch is set to its Audio position, the Model 275 will be turned on
whenever an audio signal is present at its Left and Right Input jacks. After the audio signals
cease the Model 275 remains on for about ten minutes. This prevents unintended turn-off
during pauses in your music or movies. The Audio position of the Auto Turn On switch also
disables the front panel Power button.
Note:
You will achieve more consistent auto turn on operation by using the 12V DC trigger if the
Model 275 is driving the surround, center, or rear channels. At the beginning of films the surround
channel levels are even lower than the minimum level required by the Audio sensing circuit.
12V In Jack
The Model 275 12V input uses a 2.5mm sub-mini jack. To trigger the Model 275, insert the plug
at one end of the provided trigger wire into this jack and the other plug at the other end into the
source component’s trigger output jack.
Some components, including most Parasound Surround Controllers, may use a 3.5mm mini jack
for trigger output, so we have also included a included a 2.5mm jack - 3.5mm plug adapter for
your convenience.
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