100% and High Quality Power input: AC 12V 1A 5.5*2.5 PLUG Channle: 2.0/ stereo Potentiometer Role: Volume adjustment + Power Switch FE-6J1-2 fever tube pre-amp board is the circuit schematic design imitation crew Music fax X-10D,to be rational optimization,more stable performance than the original machine,tube play 10% increase. This board uses a single 12V AC input,the circuit processing provides 6J1 tube needed positive and negative voltage and filament power supply voltage. Power works: an open power tube filament heating is started,when the boost from the zero-voltage start boosting hot filament tube,etc.,also happens to boost boosting finish,so this is the same with the guts rectification,8*470UF the capacitor filter very clean,good power supply system will not have a hum,the filament is 12V DC power supply,need two filament tube is connected in series with a DC filament also in order to reduce the noise. Color as shown Material: plastic + metal SIZE: 77MM * 75MM * 52MM Package Contents: 1* 6J1 tube preamp amplifier board 1* Transparent shell parts 1* Instruction manual 1* Screw package Note: This is Diy Kits. you need do it yourself. Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.