FT65R

The FT65R is a 65-watt line-operated Class A-B audio amplifier that was designed by known electronics engineer Tony Rohan. The amplifier features a compact design and utilizes a simple circuit topology. The power output stage employs a complementary transistor pair, with each transistor mounted on a separate heatsink to facilitate heat dissipation.

The amplifier is capable of delivering up to 65 watts of power into loads with an impedance of 4 ohms. This makes it suitable for use in a variety of applications, including home audio systems and public address systems. The FT65R also features a built-in bias detector circuit, which helps to maintain the stability of the output stage.

One of the key characteristics of the FT65R is its high current capability, which allows it to drive a wide range of speaker loads. This makes it a versatile product that can be used in both small and larger sound systems. The amplifier's input stage has a quiet background noise of 50 µV with a frequency response of 20 Hz to 20 kHz.

The circuit components are easy to obtain and the circuit itself can be repaired or maintained by anyone with some basic electronics knowledge. The FT65R received a good response from users due to its reliability, good performance, and the simplicity of its design, making it a good product to use as a basis for DIY projects or to use in home theaters.