Simple Mixer with 4 Input

Here the simple mixer with 4 input and 2 op-amps:

Simple Mixer with 4 Input Circuit diagram :

A basic mixer suitable for mixing microphones or even effects outputs. The overall gain from input to output is one if the pot related towards the input is full up. You can make this a net gain of ten (or any other reasonable gain) by reducing the input resistor towards the second op amp. 10K in this position gives a gain of ten, or 20db. In case you are mixing effects outputs that have an output level control constructed into them, you are able to dispense using the input level controls, or make some have level controls, some not. Audio taper pots are possibly much better, but linear will do the job.

For the op amps, choose a JFET input dual or singles, such as from the National Semi LF3xx series, or something such as the TL072 or TL082.

 

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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.

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