MASTER SECTION
(10) POWER ON/OFF SWITCH
This switch turns the unit on and off. The SPM-4250 uses relays to ensure quiet turn-on and turn-off.
(11) 48V PHANTOM POWER LED
Lights to indicate when 48V phantom power is turned on.
(12) ECHO EFFECTS DISPLAY
This numeric Effects Display will indicate which of the 16 echo presets has been selected.
(13) ECHO TIME SELECT BUTTONS
Use these UP and DOWN buttons to select one of 16 preset time intervals of the built-in Echo Effects DSP (Digital Sound Processor). Setting 1 selects the shortest echo time to emulate plate and doubling effects whereas setting 16 enables the longest echo time for stadium reverbs and delay sounds. Settings around 4 - 7 emulate room and hall reverbs by adjusting the ECHO DEPTH CONTROL (14) to approx ten o’clock and the ECHO LEVEL CONTROL (15) to mid.
(14) ECHO DEPTH CONTROL
This adjusts the number of repeats and feedback/depth of the echo effect selected. Turning the control clockwise sets the repeats to maximum for lengthy echoes or plate effects. Turning the control counter-clockwise sets one repeat for single delay or doubling effects.
(15) ECHO LEVEL CONTROL
This adjusts the level of the effected signal sent to the master mix bus.
(16) 5-BAND GRAPHIC EQ
The 5-band graphic equalizer allows you to adjust the frequency response of the left and right master bus signal, allowing final tonal adjustments. This provides a maximum of 12dB cut or boost from the flat position for each frequency band; 63Hz/250Hz/1KHz/4KHz/12KHz. The faders can be adjusted to easily eliminate feedback at the corresponding frequency. These EQ’s are pre MASTER VOLUME.
(17) LED OUTPUT METER
The 5-stage stereo output LED meter display the can be used to maintain proper levels in the master mix. The red PEAK LED will light when the output signal is just below clipping. It is acceptable if the red LED lights occasionally. If the red LED lights more than occasionally, you should turn down the MASTER VOLUME (24) to avoid audible distortion and clipping, which can cause damage to your speaker and even the internal amplifier.
(18) AUX SEND JACK
The AUX SEND JACK provides a mono mixed signal output from each input channel to an external effects unit or other device. The signal level is adjusted by the EFF and Volume controls of each channel.
(19) AUX RETURN
This input can be used to return the effected signal into the SPM-4250 or it can be used as an auxiliary input for line level devices. The input signal can be adjusted using the MASTER VOLUME (24) and the output volume of the external unit.
(20) TAPE INPUT / REC OUTPUT JACKS
The Left and Right TAPE INPUT RCA jacks allow cassette recorders, CD players, or MP3 players to be added to the master mix output. These signals are affected by the TAPE LEVEL (21), MASTER VOLUME (24), and 5-BAND EQ (16). The RECORD OUTPUT Left and Right RCA jacks provides signal output to recording devices, home audio equipment, or external amplifiers. These outputs are post MASTER VOLUME and 5-BAND EQ.
(21) TAPE LEVEL
This adjusts the amount of TAPE IN signal that is sent to the master bus.
(22) HEADPHONES CONROL AND JACK
This control and corresponding 1/4 output is for connecting headphones to the SPM-4250 to monitor each channel, or the master mix, dependant on the MASTER PFL (23) setting.
(23) MASTER PFL SWITCH
When this push-button switch is out, the HEADPHONES receive the main mix signal post 5-BAND EQ / pre- MASTER VOLUME. When the button is depressed, the signal is sent from each channel PFL control to the HEADPHONES. In this setting, the HEADPHONES jack can also be used as a sub-mix output.
(24) MASTER VOLUME
The MASTER VOLUME sets the level of the stereo signal sent to the internal power amplifiers.
