SPS-1 Operating Instructions - Front Panel


(Click on front panel for larger photo)

Input Level: The Input control sets the operating level. Set the input level so the signal level stays between the limits set by the Signal and Peak LEDs. The unity gain setting is 12:00.

Peak/Signal LEDs: The green 'Sig' LED indicates that the signal level at the input stage is above -20 dBu, the lower limit for proper operation. Set the Input level so this LED stays on most of the time. The red 'Peak' LED indicates that the signal level is near the upper limit for normal operation, +14 dBu, at one of the following places in the signal path: Preamp Module output, Input stage, EQ input and output, or Channel output. Set the Input Level control so that this LED flashes only occasionally.

EQ In/Out Switch: Pressing the EQ button illuminates the red 'on' LED and puts the 3 band Parametric EQ into the signal path.

Three Band Parametric EQ
: Each of the three bands (LO, MID, HI) of the EQ has three controls:|

Frequency: The ranges are: LO: 35 - 880 Hz MID: 180Hz - 4.2KHz HI: 840Hz - 19KHz
Bandwidth: The bandwidth control sets how wide or narrow a range of frequencies around the center frequency are affected. The range of adjustment is: LO: 0.1 - 1.0 octave. MID and HI: 0.33 - 1.0 octave
Level: The level control sets the amount of boost or cut (± 15 dB maximum) that is applied at the center frequency.

Master Output Section

Pan
: The pan controls determine the left (ccw) and right (cw) position in the stereo mix for Channel 1 (top) and Channel 2 (bottom).
Master Level: This control sets the level for the Left and Right balanced outputs on the rear panel. The unity gain setting is 2 o'clock.
Phase Rev: Press this switch to reverse the overall phase of the Master Outputs. This can be useful for feedback control.
On/Loop: These two LEDs indicate the status of the mute and effects foot switches. The 'On' LED (top) indicates that the master, monitor and channel outputs are active. The 'Loop' LED indicates that the stereo effect loop in the master output section is active. When the footswitch is not used, the 'On' LED is always lit, and the 'Loop' LED lights when an effect device is plugged into the stereo effects returns.

Monitor Output

Monitor Level
: This control sets the level for the Left and Right 1/4" unbalanced outputs on the rear panel.
Phase Rev: Press this switch to reverse the overall phase of the Monitor Outputs. This can be useful for feedback control.
Monitor Source Switch: The Monitor outputs are normally fed the master stereo mix (MIX), which is identical to the Master outputs. Press this switch to feed Channel 1 directly to the monitors. This can be useful for controlling feedback in pickup/mic applications, by feeding the pickup-only signal from channel 1 to the stage monitors.
Phones: This is a separate output stage for driving a set of stereo headphones. The output level is determined by the Monitor Level control.