1. Using 6J5 tube, NE5532 3. The resistor uses high-precision chip resistor to ensure a good signal-to-noise ratio of the whole machine. 4. PCB adopts 1.6mm thick double-sided sheet, 2.0 oz copper thickness, and tin-spraying process to ensure good passing performance of large and small currents. First-class PCB quality. 5. The input and output are made of gold-plated RCA lotus seat, which is durable and beautiful The board layout is reasonable, beautiful, and the current is small. Basic parameters: Power supply: DC12V2A ( needs to be regulated by 12V, not higher than 12V) Machine size: about 129* 100* 35MM (without tube height) Panel function: switch treble adjustment bass adjustment total volume Note: 1. This finished machine is a preamplifier, not an amplifier. It should be used with a post-amplifier or an active speaker. It is not allowed to directly connect passive speakers, speakers and earphones to the power amplifier; if it is not used, the car will be burnt if the voltage is unstable. 3. Make sure that there is no problem with your source. The preamplifier itself has a preamplifier function. If the source itself is noisy, then the preamplifier will only amplify its noise. Please use a good source test. Note: Power supply is not included in the package. You need to buy 12V2A power supply by yourself. Material:Aluminum alloy colour:Silver Package Contents: 1 * 6J5 Tube Preamplifier 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.