RS30 is an amplifier made by HH SCOTT in the 80s which is capable of producing up to 25 Watts of audio output at a load of 4 Ohm.
Inside the Power Amplifier section, symmetrical supply voltages of 35VDC and +15VDC are need to supply the Q501 and Q502 pre-amplifier circuits.
The appearance of the amplifier is in THIS LINK.
You also can view the inside of this amplifier can be seen on THIS LINK.
This amplifier also has an internal tone control which is using feedback from the output of amplifier.
SCHEMATIC DIAGRAM
The following is a cropped amd edited schematic from the original one.
From the schematic image above, I can explain as follows:
The input signal goes to the preamp transistors Q501 and Q501 as differential amplifier.
The GAIN of the amplifier is depending on the Tone control potentiometer.
Truely, this amplifier is a tone regulator with an amplifier in it. The output of Q501 will then be amplified by the transistor Q508.
While the Q507 serves as a current mirror only. Q505 serves as a servo driver for this amplifier circuit to limit the idle current on the power transistors Q515 and Q517.
Q513 and Q515 are amplifier drivers which is to amplify the current from the input signal.
Lastly, Q515 Q517 ( TIP41C ) which serves as the final output transistor.
TIP41C are transistor with maximum output at 65 Watts ( DATASHEETS ).
