DC buffer stereo preamp circuit board: high impedance input and low impedance output, no amplification gain, driving strong influence after reducing the level of input, from the past and the effect on the sound of great benefit.NOTE: Now the color of the board is Green or yellow.PCB board (double-sided solder resist, size 61 × 43mm thick copper foil, thickness 2mmImmersion Gold PCB high quality red plate (double-sided solder, size 61 × 43mm 72 μm thick copper foil, thickness 2mm. The line signal input-output DC-coupled, without coupling capacitors, Output midpoint DC potential 0 volts adjustable. DC ± 5V to ± 15V supply.Imported RC element assembly, Nissan "KOA" 1 / 4W colored ring precision metal film resistors, American and S NE5534, imported silver-plated IC sockets easy to upgrade, Japanese filter electrolysis, high-quality terminals.Plastic NE5534 board can be replaced with other types of single op amp, such as the OPA627, AD847, AD797, OPA637 and so on. Selected larger current consumption of the op amp sounds better then ± 15 can work, input and output using terminals, the board left four mounting holes to facilitate fixed.The preamplifier board best design for OPA627, if the NE5534 single OPA627 op amp upgrade directly to a single operational amplifier, have an immediate effect, it is worth a try! Stereo, CD, replace the op amp amplifier Manifold Mount machine tool. (need buyer purchase OPA627)Actual data:OPA627 parameters: voltage feedback, JFET-type, high-precision, high speed. Power supply voltage; ± 4.5 ~ ± 18V, differential input voltage: Vs + 4V, input voltage: + Vs + 2V ~ -Vs, allow power: 1000mW, low noise: 4.5nV, high speed build: 550ns, low offset voltage: 100uV, low voltage drift: 0.8uV / ℃, gain bandwidth of 16MHz, the conversion rate of 55V / US, distortion of 0.0006%, CMRR 110dB, current consumption ± 7.5mA.The buffer circuit is simple, wide range, High Definition force, rich in detail, tonal balance, drive and strong, easy to match and after the class. Its quality depends on the merits of the op amp's performance.Friendly reminder: use the time to pay special attention to the input voltage should not exceed ± 18V, a DC voltage of positive and negative polarity not connected correctly. Circuit board NE5534 manifold is used to disassemble product.