New Creative Pure Class A Amplifier

In the circuit of this machine , two sets of independent operational amplifiers (NE5532) are used to form two complete
single-ended amplifiers. They both work in pure Class A
mode and each independently form a full-waveform amplifier with excellent performance
. The amplified signals
are then organically mixed at the output point, effectively reducing
odd-order harmonic distortion that is extremely harmful to sound quality.
The bipolar transistors (VT1 and VT2) of the excitation stage are used as current
control devices to draw the required base current directly from the output terminal of the op amp
, which is a more ideal
way of use. VT3 and VT4 are used as
VT2 and VT1 respectively. Constant current source load. This ensures
the stability of the entire machine and eliminates troublesome
debugging procedures.
    The VT1 and VT2 of the excitation stage and the two high-power transistors of the output stage form a cross-guard coupling mode. Due to
the clamping effect between the operating points of each triode , the stability of this circuit is excellent, and there will be no inrush current sound at the moment the power is turned on. Another benefit of the cross
-coupling platform is that the excitation stage and the output stage draw operating current from the positive and negative power supply terminals respectively, which is
very beneficial to improving the common mode rejection ratio of the amplifier. The operating current of the excitation stage is as high as 85mA, and the operating current of the output stage is as high as 85mA. It is as high as 1.7A
(two tubes connected in parallel). Due to the large current of the machine , a large enough radiator must be added to each transistor (including the excitation and relaxation constant current source load
transistor ) during production, and the power transformer must have sufficient margin (150w is recommended) ). Since this machine
has strong adaptability to power supply, the power supply circuit only needs simple adjustment and filtering. If qualified,
a 1~2H inductor can be connected in the power supply circuit to obtain better results.