Description: R27 is reverb depth resistor, if you want it can be adjustment, please remove R27 and connected a potentiometer to the SGG pad, the potentiometer value range is 20k-50k. Note: just Reverb Plate, without Preamplifier FunctionSpecifications: Name: PT2399 Microphone Reverb Plate Working Voltage: DC 6-15V Board Size: 50x50mm/1.97x1.97inch Quantity: 1 PcNote: Please allow 1-3mm error due to manual measurement. pls make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!No Retail Package Package Includes: 1 x PT2399 Microphone Reverb Plate