74.3. Channel gainAll the SMAC input channels have accessible input sensitivity GAIN (2) controls.These controls have the function of compensating for differences of level existing between thesound sources connected to the table.The gain controls have a variation margin of ±15dB (channels 1-2) and ±20dB(channel 3). All GAIN adjustments must he done very carefully using the VU-METER as areference and avoiding that all the red LEDS of the VU-METER light up, input could be cliped.4.4. Channel equalizationInputs 1 and 2 are provided with a 3-way tone control (6-7-8) of wide range ofoperation, -30 to +10dB for bass and treble and –25 to +10dB for medium. This wide rangeenables a progressive KILL effect instead of the sharpness of the ISOLATOR switch (11).Channel 3 is provided with a conventional two-way tone control with a ±15 dB range.4.5. Long-life Crossfader with VCA.The addition of the Voltage Controlled Amplification (VCA) control to the fineness,precision and mechanical strength of the crossfader has resulted in an operating life greaterthan 300,000 operations. That means that the SMAC PRO20 crossfader operating life is 30times greater than a high-quality mechanical crossfader.4.6. Changing the crossfader.Once the operating life of the crossfader has ended, it can be changed very easily.Replace the old crossfader by a new one and the system will operate as the PRO20 day. Tochange the potentiometer proceed as follows:1.-Remove the screws from the cover.2.-Disconnect the multipin connector.3.-Remove the crossfader screws.4.-Replace the crossfader by a new one.5.-Fix the crossfader screws.6.-Connect the multipin connector.7.-Place the cover and fix the screws.Always use original ECLER GENUINE SPARE PARTS for your SMAC.