The thick-film STK3048-driven STK6153 power amplifier circuit, a golden toy of the 1990s, boasted a delicate and transparent sound, powerful low frequencies, and a unique flavor of thick film in the midrange. It exhibited low distortion and a wide dynamic range, making it highly distinctive. At that time, it was sought after by many audiophiles and enthusiasts.
STK3048 is a pre-stage voltage amplifier integrated circuit; STK6153 is a post-stage current amplifier integrated circuit. STK3048 is a dual-channel single-in-line thick film package, featuring two stages internally. The input stage includes a protected differential amplifier, and its collector's resistance-capacitance series phase compensation network prevents transient distortion caused by sudden signals in the input stage. A set of mirrored current sources is connected between the two collectors. The main voltage amplification stage is a common-base common-emitter circuit. The upper transistor performs broadband amplification of the signal and provides impedance matching for direct coupling between the input and output stages; the lower transistor linearly outputs the amplified current of the upper transistor to reduce the open-loop distortion of this stage and provide greater excitation power to the post-stage. Both stages of amplification tubes are supplemented with constant current sources as loads, providing strong suppression of power supply ripple.
STK6153 is a single-channel, single-in-line thick-film package that integrates a constant voltage source bias, a pre-driver, and an output-stage composite current amplifier circuit. It adopts a fully complementary symmetric structure and features high speed, high precision, high power, and low noise. Due to the built-in constant voltage source bias, the output-stage high-power transistor is always in its optimal operating state, providing excellent temperature compensation. The complementary output stage of this thick-film module is designed as an inverted Darlington composite circuit, with an open collector output to reduce output impedance.
Circuit characteristics:
● Classic thick film combination STK3048 promotes STK6153.
● DC midpoint voltage servo, with midpoint voltage almost at zero.
● Current-mode negative feedback.
● Two original 10000uF 50V Rubycon Ruby rectifying and filtering capacitors.
● Equipped with a horn protection circuit and a high-current Omron relay.
● Equipped with a high-performance operational amplifier feedback-type volume control circuit, eliminating the influence of resistive potentiometers.
Parameter
Power supply voltage: AC dual 18V-33V
Output power: 85W at 8Ω, 100W at 4Ω
Maximum signal input: 5V
Magnification: 38.2 times
Frequency response: 25Hz-20kHz/±2dB
Left-right channel separation: 40dB
THD+N (Total Harmonic Distortion + Noise): 0.05%
Output load: 4-16Ω
Output channel: 2 channels
Size: 153.72*101.65mm
Weight: 275g
