FE-6J1-2 fever tube pre-amp board is the circuit schematic design imitation crew Music fax X-10D,to be optimization,more stable performance than the 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 supply voltage. works: an open tube filament heating is started,when the boost from the -voltage boosting hot filament tube,etc.,also happens to boost boosting finish,so this is the with the rectification,8*470UF the capacitor filter very clean,good supply system will not have a ,the filament is 12V DC supply,need two filament tube is connected in series with a DC filament also in order to reduce the noise. 6J1 Tube Buffer 0.85 magnification, connected between and before or after class, can effectively filter digital flavor. AC 12V input: The DC3.5 / 5.5 x 2.1 socket, 12V AC adapter, if you non-plug AC 12V transformer, cord need to solder on the circuit board. Remember: You can not a DC input, otherwise it does not work! the left-channel input / right channel input: audio signal input, can be connected to mobile phones, computers, , the MP4, and other music players. the left channel output / right channel output: an audio signal output terminal can be connected to the audio signal input amplifier, amplifier board. the switch / volume knob: turn the knob counter-clockwise to decrease the volume beginning, when the volume to the minimum, if it continues to rotate until the "ticking" sound, then the off, the light goes off; in the closed state, Turn the knob clockwise to hear "tick" sound, light is on, the is turned on, then the volume is , then continue clockwise is to increase thevolume. Type: 6j1 tube input : AC 12V 1A, 5.5x2.5 plug Channel :2.0 / stereo Potentiometer Role: Volume adjustment + Switch Size: 77 x 75 x 52mm Colour:As shown Material:PC+Metal Package Contents: 1 x 6J1 preamp amplifier board diy kits Only the above package content, other products are not included. Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.