Parameters
1. Power supply: DC+-(35V-55V) recommended +-45V and AC12V
2. Power: 300w (total harmonic distortion THD+N<0.1%), DC+-45V, 4 ohms
3. Class A 90W, measured under 4 ohm load
4. Speaker impedance: 4-8 ohms.
5. PCB size: 59*236MM.
6. Adjust the differential input stage current to 2MA: Adjust the VR1 (500R) adjustable resistor so that the voltage between C and D is 1.5-2V (that is, the voltage across the R9 (1K) resistor); the input differential current is 1.5- 2MA, this value is the best sound quality
7. The quiescent current of the large tube is 100MA: Adjust the adjustable resistance VR2 (1K) so that the voltage of the two points A and B is 22MV. At this time, the quiescent current I=22MV/0.22R resistance is 100MA; if the customer heat sink is large enough, it can make Increase the quiescent current, generally 100MA-300MA sound effect is best.
8. A pair of boards with left and right symmetrical output inputs

Features
1. Use original Toshiba A1943/C5200 and 2SA1930/2SC5171.
2. The interstage coupling capacitor adopts WIMA top capacitor 1UF, and the main circuit of electrolytic capacitor signal adopts imported Panasonic brand name to ensure strong and continuous power support.
3. The resistor is made of five-ring metal resistor. The main circuit uses a five-ring metal film resistor with an accuracy of ±1% to ensure a good signal-to-noise ratio.
4.PCB adopts 1.6mm thick double-sided sheet, 2.0 oz copper thickness, and spray tin full process to ensure good passing performance of large and small currents. First-class PCB quality.
5. The biggest feature of this board is the use of the current advanced C1237 BTL speaker protection circuit, effectively eliminating the impact sound and DC output protection function of the open and shutdown, making your speaker more secure.
6. The layout of the entire circuit board is quite rigorous and reasonable, and the overall PCB trace adopts a grounding method. The power amplifier board works stably and reliably, and the output power is large; the sound is beautiful and round, and the sound field is wide. The three-dimensional sense is strong, the low frequency is solid and solid, the signal-to-noise ratio is quite excellent, the dynamic range is wide, the details are clear, the transient response is excellent, and all kinds of music are played comfortably. It has a very good performance in the family's playback environment.

Package
1 pair of E405 Amplifier Board Reference Accuphase Circuit Power AMP Board