2SC2922 and 2SA1216 or 2SC3264 and 2SA1295 power amplifier circuit

Amp 2SC2922 and 2SA1216 (or 2SC3264 and 2SA1295) performance is very excellent more, it is good linearity, strong overload. Use it as a high-fidelity power amplifier stage amplifier, the performance is very excellent photos.
2SC2922 and 2SA1216 or 2SC3264 and 2SA1295 power amplifier circuit - schematic

Figure 2-30 for the use of the principle of the tube production of high-performance amplifier Figure o circuit consists of a differential input stage, stage differential voltage amplification level and to promote full and complementary push-pull amplifier output stage. In addition, this also has overload protection circuit and speaker protection circuitry. At the input, low-pass filtering by the clamor RI, c2, C3 composed of upper frequency limit the input of the circuit to reduce the transient state intermodulation distortion. VTl, VT2 constitute a differential input stage o VT3, VT4 constitute a differential voltage amplifier stage, VT4 collector output directly connected to the input A tube amplifier output VT70Vr5, VT6 composition of the current mirror, VT3 collector outputs VTs set a base connection input base VT6 pole after VT6 enlarge its collector output and the input amplifier output tube VT80 VT7, VTG, VT8, VTlo composite pipe consisting of complementary push-pull amplifier output stage. VT12, f) 4 and VT13, f Ga composition of output overload protection circuit. VT14 ~ VT16 composition speaker protection circuitry allows the speaker 5 seconds after the power is turned on access to avoid the boot impact. It can automatically cut off the speaker when the DC voltage exceeds the output of 1-5V. DC amplifier circuit due to the cancellation of the feedback capacitance slightly after the input differential stage feedback input to ground the DC bias resistance will wind "I RF &; RF, RF generally only about 1kfl. In order to strike a balance differential pair, a signal input resistance to ground J52 should also be reduced to the RF level. This will reduce the input resistance of the circuit a lot, and not easy to take a pre-stage was a good match. For this reason the general : Multi-voltage control amplifier circuit FET device as a differential input stage o The input stage circuit still use bipolar transistors, but the base bias resistor and the input resistor is provided separately (principle shown 1 35 (a)), to adjust the balance of the circuit by trimming potentiometer neither reduce the input resistance, but also to achieve the level of the differential circuit Qiao regulation, after all, a good solution. Because of the differential input is biased, so the input capacitance Cl not free to cancel o Another feature of the circuit is the use of suspension grounding. Suspension ground of the unit is in the ground portion input taken by the two regulator and a resistor R13, the negative supply it with isolation amplifier stage. So it can make the power supply circuit of the thermal noise generated by a large current channeling people not to enter the loop. On the other hand it can also inhibit the production of anti-speaker playback when the electric potential of channeling people to the input circuit to produce "Interface hum modulation distortion" (abbreviated as IHM distortion).

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