PREAMP GAIN ADJUSTMENT The preamp gain in the Bass Micro Synth has been set at the factory for use with a bass equipped with single-coil passive pickups. If you will be using another instrument with higher or lower output, it may be necessary to readjust this setting. A screwdriver or alignment tool with a tip width of no more than 1/16″ is required. To access the preamp gain adjustment, remove the bottom plate from the Bass Micro Synth. Look for the small trim pot in the lower left corner of the circuit board, it is labeled TRIM1 GAIN TRIM. Turning the trim pot clockwise will increase the preamp gain. Turning it counter-clockwise will decrease preamp gain. Please do not touch any other components when the bottom plate is removed or you risk damaging the circuit board or the components. So maybe you can look up in the setting of it.