R E A R C O N T R O L S A N D C O N N E C T I O N S
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Bottom
Panel
7.BALANCED INPUT CONNECTORS (1/4" TRS & XLR) These 1/4" (6.3mm) TRS (Tip/Ring/Sleeve) phone jacks and XLR jacks are compatible with balanced inputs and are wired as Tip/Pin 3 =
Since the channel TRS phone jacks and XLR jacks are wired internally in parallel, you can parallel this unit with another amplifier by using either the LINE 1/4" jack or the XLR jack (depending on which you’re using to input your signal) to output the signal to the input jack of the other amplifier.
The 1/4" TRS phone jacks can also be used for unbalanced inputs. For TRS phone plugs, simply connect the unused side of the balanced input to ground. For 1/4" TS phone plugs, no change is necessary for compatibility with this input. Balanced input signals are recommended as they are less prone to AC hum. For long cable runs a source of less than 600 ohms output impedance is needed to avoid signal loss. For short cable runs an unbalanced signal input should be suitable.
(Note: Do not use both unbalanced and balanced cables in the same
For stereo
8. INPUT LEVEL SWITCH
Sensitivity slide switch offers 3 sensitivity inputs of operation; 0.77 volts, 1.0 volts & 1.44 volts.
9. MODE SELECTOR SWITCH
The SPA Series amplifiers offer 3 modes of operation: PARALLEL, STEREO & BRIDGED. Slide the switch to one of the three positions for your application.
•PARALLEL (MONO) INPUT — This mode allows both channel outputs to operate in parallel with the same signal. In this mode, use channel 1 input and Level Control to operate Channel 1 and Channel 2 Speaker Outputs. Channel 2 input is not operational.
•STEREO INPUT — This is the most common mode generally used, and allows independent control of 2 separate signals such as stereo, main and monitor live mixes, and bi- amp operation (highs in one channel and lows in the other).
•BRIDGED MONO — This mode combines the power of both channels to drive a single speaker. Connect the input signal to Channel 1 input for bridged mono operation. When in Bridged mode, use the red binding post (banana jack) outputs only. If Channel 1 and Channel 2 outputs are used, the Speakers will be out of phase.
(CAUTION: This amplifier can deliver high power into a speaker. Make sure that the speaker can handle the power output of this amplifier)
10. GROUND LIFT SWITCH
Switch to disconnect the chassis from ground if necessary to eliminate hum caused by ground loops.
11. SPEAKER OUTPUT CONNECTORS
Speakon™ and binding post (banana jack) outputs are compatible with a speaker load of 4ohms or greater (8 ohms or greater for bridged operation). Do not use less than an 8 Ohm load when in Bridged mode. Connections are as depicted on the rear panel.
12. FUSE HOLDER & POWER CORD CONNECTOR
This fuse holder contains an AC primary fuse. When this fuse blows, replace it with the same type fuse, size and power rating (see SPECIFICATIONS). If it continuously blows, stop replacing the fuse and refer servicing to qualified personnel. The cord connector is used to connect the AC power source to your power amplifier.
(CAUTION: After checking the AC supply voltage, be sure that the correct fuse is in the fuse holder.)
CAUTION: DO NOT REMOVE THE AC PLUG CENTER GROUNDING PIN.
13.INPUT VOLTAGE SELECT SWITCH (BOTTOM PANEL) Select 115V/60Hz or 230V/50Hz as appropriate for your area.
(CAUTION: Selecting the wrong voltage can damage your unit. See also POWER CONNECTION, pg 6)
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