The people who listened to the sound that comes out of this board were amazed. I play saxophone and I'm very difficult about the sound which is coming out of a speaker. And yet, I DEFINITELY LOVE this sound! Based on a published electronic circuit, I redrew the board and optimized the choice of the components, the electrical specifications, the heat's dissipation, the PCB technology, the tracks width and the connection of the cables on the PCB, in such a way to improve the sound's quality. This product fully applies RoHS standards. I'm proud to present you this dazzling, pure and powerful class AB low noise analog amplifier board, which is very small if we consider the output power: only 38 electronic components on a 82 x 94.5 [mm] FR4 board for 242 [WRMS] output power without any visible distortion or oscillation! I've oversized almost every component and most of them are no more through hole but now SMD type. Moreover, I've put many holes around the resistors and the diodes to dissipate the heat through the circuit. And I don't use connectors, but only wires soldered directly on the PCB. Electrical Specifications: > Minimum speaker's load of 4 [Ω] allowed. > Measured 156 [WRMS] on a 8 [Ω] resistive load with a +/- 60 [V] power supply and a supply current of +/- 2.4 [A]. > Measured 242 [WRMS] on a 4 [Ω] resistive load with a +/- 60 [V] power supply and a supply current of +/- 4.3 [A]. > Measured 5 [Hz] to 40 [kHz] bandwidth at -3 [dB]. > 12 [kOhms] input impedance. > 1 [VAC] input sensitivity. > Main capacitors of minimum 2 x 20'000 [uF] 63 [V] required. > Main toroidal transformer of 500 [VA] with 2 x 40 [VAC] secondary outputs required. > Accepts main DC voltages of +/- 60 [V] maximum. > Needs a section of 4 [mm2] for wires of the +60 [V], -60 [V] and speaker output. > Needs a section of 6 [mm2] for the ground wire. > Needs a very good audio shielded wire for the audio signal input.