4 Channel Audio Mixer Circuit Diagram

A 4 channel audio mixer that requires very few electronic components can be built using this electronic scheme based on SSM2024 chip. To obtain a small offset and a high rejection, the four inputs of the 4 channel audio mixer circuit must have an impedance of 200 ohms to the ground. These impedances are resistances obtained with R5-R8, which are part of the voltage divider at each input. With values of the components from this scheme nominal input signal is 1 V (0 dBV). At this level, distortions are about 1%, and at lower levels do not exceed 0.3%. Maximum amplification is obtained for a control current of 500 uA, in which case the input control voltage is slightly increased to 0.5 V (result we need a maximum control voltage of 5.5 V). The amplifier output currents are summed by simply connecting the output pins. The signal / noise of the mixer is about 90 dB and the bandwidth of the order of 130 kHz. SSM2024 integrative work satisfactorily with a supply voltage between 9 V and 18 V, but best results are obtained at ± 15 V.

Subwoofer Amplifier Circuit 60W

Using the STK4038X audio amplifier IC, can be designed a very simple high power and efficiency audio power amplifier . This circuit is manufactured by Sanyo Corporation and will provide a output power of 60 watts on a 8 ohms load or 4 ohms load with 0.008% distortion . The output power that is provided by this audio IC , can be more higher , but with more distortion.If you will use a 8 ohms load you must power this audio amplifier project from a dual +/- 40 volts DC power supply and if you’ll use a 4 ohms load you must power this audio project form a dual +/- 33.5 volts DC power source. To prevent over heating the STK4038X audio power IC must be heatsinked on a good heatsink . Also you must use a very well filtered power supply ( a 10000uF capacitor will be fine for this audio project) .

Speaker indicator

With this indicator you can see how much power an amplifier delivers. The circuit uses a LM 3915, the logarithmic variation of the known LED VU meter IC LM 3914. The circuit is connected directly to the speaker output of the amplifier, and the power state of 0.2 watts to 100 watts. The sensitivity of the circuit can be varied with R1. The basic settings are shown in the table.

 

• R1 = 10 k (see text)
• R2 = 10 k
• R3 = 390 Ω
• R4 = 2.7 K?
• C1 = 22 V μF/25
• LED1-LED10 = LED (color of choice)
• IC1 = LM 3915

Microphone amplifier

The preamplifier amplifies the output signal of a microphone, so that it can be. The further amplified by a power amplifier The circuit provides an output signal line. With two transistors, it is not difficult to build such a circuit. The amplifier produces little noise. In the shown embodiment, the circuit is suitable for microphones 500 and 600 Ω. 200 Ω R1 microphones should be reduces to 220 Ω and C1 should be increased to 4.7 uF. The gain is set by R2. If the average declared value of 22 K? Can be used. The maximum gain is about 200times.

• R1 = 470 Ω
• R 2 = 22 K?
• R3 = 12 K?
• R4 = 47 k
• R5 = 820 Ω
• R6 = 100 Ω
• R7 = 1 k
• R8 = 100 k
• C1, C4 = 2.2 V μF/16
• C2 = 47 V μF/16
• C3 = 470 nF
• T1 = BC 549C
• T2 = BC 547B

Microphone Preamplifier

This is a good pre-amplifier for microphones that can be. Used in, for example, mixing consoles The circuit operates with a dual op-amp type NE 5532. The amplifier must be adjusted. Simply plug the power and control over P1 such that half the supply voltage (6 V) on pin 3 of IC1 state. P2 is then adjusted to the desired volume.

• R1 = 8,2 kW
• R2, R4, R5, R6 = 10 kW
• R3 = 1 k
• P1 = 4.7 K?
• P2 = 100 k
• C1, C2, C4, C6 = 10 uF
• C3 = 470 nF
• C5 = 100 nF
• IC1 NE = 5532

Phono/line adapter

In older amps usually have a phono input is available. Today, it is used less and less, and therefore it would be useful if the input can be. Used as line input With this circuit it is. the circuit is actually an attenuator and a filter. The signal is attenuated to the level of a phono-receiving element, and filtered to the RIAA equalization is undone in the amplifier. On 'in' is the line signal, and is connected to the phono input 'from' the amplifier.

• R1 = 1 M 1%
• R2 = 82% 1 K?
• R3 = 1 k 1%
• C1-C4 = 1 nF 1% Styroflex

Peak Indicator

This indicator can be used, or to see if you can get the sound output. Damaged speakers with P1 lets you set the limit at which D1 LED lights. The potentiometer is 100k here, you can experiment. Themselves with other values ​​if you could turn a logical port on the LED or opto coupler would use, you can turn it so that the signal between the preamp and power amp would fall away. Or that the signal to the speakers with the aid of a relay would be turned OFF.

• R1 = 680 Ω
• R2 = 1.2 K?
• P1 = 100 k linearly
• B1 = 4 x B250C1000 or 1N4003
• D1 = LED
• T1 = 2N3904