After improving the quality of power MOSFET transistors and reducing their price, a huge part of radio amateurs began to think about using these transistors in the output stages of amplifiers. And if, the first “field workers” sinned with some kind of blurryness, then with the development of the circuits and the devices themselves, the problem of sound quality began to gradually go away.
It should also be noted the undoubted advantages of field-effect transistors over bipolar ones:
1. PT can withstand noticeably large impulse loads, or rather overloads.
2. The absence of input currents, in some cases, makes it possible to significantly simplify the swinging cascades.
3. The parameters are less dependent on temperature, besides they have a large linear section of the transfer characteristic.
The amplifier is assembled on 5 pairs of quasi-complementary output transistors IRFP250N (Dismantling) with asymmetric preliminary stages, the module is also equipped with a thermal stabilization and quiescent current control circuit.
When using 8 ohm acoustics, the supply voltage can be raised to 75V (limit value) to obtain the equivalent power at 4 ohms.
The module is easy to set up and requires only setting the quiescent current, depending on the supply voltage. The optimal quiescent current of the output stage is 30-60mA, which is approximately equal to 100-200mA for the power supply of the module as a whole. To adjust the quiescent current, the input is shorted, the load is turned off, the ammeter is turned on in the gap of one of the supply arms and the required value is set using a trimming resistor on the board, after which a pause of 5-10 minutes is needed. to warm up the radiator. You should focus on the acceptable temperature of the radiator (+ margin for a closed case).
The module is mounted on an aluminum radiator profile and requires active cooling. The hole drilling accuracy must be very high, as the holes must match exactly with the holes on the module PCB.
Subjectively, the amplifier pleased with the sound quality, it can be used for any acoustics, including subwoofers, with suitable power parameters.
The module can be recommended for building a high-quality concert amplifier for broadband acoustic systems or a low-frequency link.