STK Power amplifier circuit,100W-150W using STK4048

If you are looking for a high-quality 100w-150w amplifier with low distortion. This may be a good choice. Some called it STK power amplifier series are hybrid IC of Sanyo.

Why is it interesting?

STK Power amplifier circuit,100W-150W using STK-4048, STK4040

STK power amplifier circuit has low distortion of about 0.003% only.

The heart working of this circuit is the hybrid IC of Sanyo. It is usually found in expensive audio equipment.

ICs STK watts list

The ICs that use has three wattages to choose the number below.

STK4044XI = 100W
STK4046XI = 120W
STK4048XI = 150W

As the following table shows the features of the IC table 1.
IC family STK4044XI, STK4048XI have developed various models from STK4044II, STK4044V, and STK4044X respectively, Until the STK4044XI model we use in this circuit.

the datasheet of STK4036XI Series
Table 1 the datasheet of STK4036XI Series

The IC has the internal circuit different due to improved, which external circuit can be used instead of directly.

For this reason, we say that. Be careful before buying it Some may be subjected to such a low-quality version of the ICA STK4044II.

compare between STK4036II and STK4036XI
Table 2 compare STK4036II and STK4036XI

Consider the comparison feature of Table 2, you will know the difference.

See real STK4048XI. You may buy it at


Figure 1 will see that the internal circuit in STK4044XI and STK4048XI that will be have the beginning circuits same together will be different than the output section of STK4048XI will have two output transistors to parallel, allowing for increased wattages up to 150 watts.
the inside ICs circuit
See inside IC STK amplifier  circuit

Thus, at 15 pins of first will be same, but in this circuit have the output and input pins are 3 pins only as figure

STK Power amplifier circuit schematic using STK4044, STK4048

See The real schematic circuit diagram of this project

In the PCB layout and components layout which we are designed to be shared by the three numbers as above, if the number STK4044XI released them float the 16-18 pins.

The PCB layout of STK power amplifier 150 watts

components layout amplifier STK-4048

The components layout

50V Dual Power Supply Circuit
50V The power supply circuit

How it builds

Connect the device to the circuit properly, especially since the electrolytic capacitors do not reverse polarity is strictly prohibited. Because of the relatively high power circuits used in capacitors may explode easily.

When an assembly is complete, connect the power supply voltage to this circuit.

Caution! This project needs to use the speaker protection circuit. Otherwise, your speaker may be damaged.

Parts you will need

IC1(100W): STK4044XI
0.5W 1% Resistors
R1,R5: 1K
R2: 56K
R3: 560Ω
R4: 10K
R2: 100Ω
R8: 56K
R9,R14: 10Ω  1W Resistor
R10: 0.3Ω 5W Resistor
R11,R12,R13: 0.3Ω 5W Resistor
C1: 470pF 50V MKT capacitors
C2: 4.7uF 25V Electrolytic
C4,C17: 100uF 100V Electrolytic capacitors
C5* : 100pF(470pF) 50V MKT capacitors
C7: 0.001uF 50V MKT capacitors
C9* : 3-5pF 50V MKT capacitors
C10: 1uF 50V Electrolytic capacitors
C11: 0.1uF 63V MKT Capacitors
C12,C14: 10uF 100V Electrolytic Capacitors
C13,C15: 1-100 MKT
C16*: 47pF 50V MKT Capacitors
L1: Coil 22T #18AWG Dia.5mm

The device marked with * is used in cases as the growth rate decreased from 40 dB to 26 dB.

The power supply
T1: (100W) 5A Sec. 35-0-35
(120W) 5A Sec. 38-0-38
(150W) 5A Sec. 42-0-42
D1: Bridge 10A 200V
C1: 0.1uF 250V X-cap capacitors
C2: 0.01uF 100V MKT capacitors
C5,C6: 10,000uF 63V electrolytic capacitors

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19 thoughts on “STK Power amplifier circuit,100W-150W using STK4048”

  1. I am very interested in this circuit (100-150W Super Hybrid Low THD Power amplifiers using STK-4048), I want to know if it is possible to buy a kit and how can I do. I live in Rome and Italy, I do not know where to turn.
    Aldo Rizzo
    [email protected]

  2. i hope you could indicate the technical specs of the circuit such as frequency response, distortion ( indicated already ), power supply and others.

  3. I have 320watts Sub-Woofers(8″)-2, 20watts(8″)speakers-2, 50watts(4″)Twitters-2.
    I very much interested to build a home theater. Please suggest which series STK circuit Board use for make a amplifier. please send details in my mail ID ([email protected])
    —– Mahesh Bahadursha

  4. Choosing Heatsink for STK4048XI
    Which size of heatsink is recommended for single STK 4048XI and for Stereo can we use one heatsink for both or using separate is better ?
    Waiting for reply

  5. Hello,
    Your schematic of the dual 50v power supply shown using a transformer with 35v output. With the capacitors in the circuit it will output 50 volts?

    Note: What do you mean by this???
    The device marked with * is used in cases as the growth rate decreased from 40 dB to 26 dB.

    What do you mean by this?? (if the number STK4044XI released them float the 16-18 pins.)
    Appreciate your time in replying.
    Thank you, Ed

  6. Hello Apichet, I built the 150 watt audio amplifier using the STK4048XI. It works great
    with a simple condenser microphone. I can hear myself loud and clear out the speaker.

    When I hook up my cell phone to the input to play music it’s awlful sounding music scratchy and static. I’m just a hobbist so I don’t know why. Any help would be greatly appreciated. Thank you, Ed

  7. Try lower your volume on cell phone output. If microphone works well there’s a good chance you’re over driving thefront end of the Amp circuit. Best of luck!

  8. Input gain is more. That’s why. You can give a preset to decrease or adjust the input gain in between cell phone and amplifier.


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