Mixers

A lot of friends ask me a circuit AUDIO MIXER, for various uses. I will begin with a circuit which you can it manufacture, as you want. This you can place in the MODULES of inputs any circuit you want, depending on the use that you intend the MIXER, the same is also for the number of input channels, that you will manufacture. Below I will give enough circuits with various levels of quality and complexity. All the circuits that propose and are simple also they maintain, a very good level of quality. For those who they are interested they can make few patience. Shortly I will give project, professional level console of mix signals of sound.

The mixer circuit below has 3 line inputs and 3 mic inputs. The mic inputs are suitable for low impedance 200-1000R dynamic microphones. An ECM or condenser mic can also be used, but must have bias applied via a series resistor. As with any mixer circuit, a slight loss is always introduced. The final summing amplifier has a gain of 2 or 6dB to overcome this. The Input line level should be around 200mV RMS. The mic inputs are amplified about 100 times or by 40dB, the total gain with the mixer is 46dB. The mic input is designed for microphones with outputs of about 2mV RMS at 1 meter. Most microphones meet this standard.

This simple circuit will fit in a stomp box size enclosure and is perfect for your pedal board to mix parallel effects. Op amp is a TL072.

This is not a "do everything" mixer but it is ideal for what I need it for and it handles a line input just fine. I made it so all the jacks are in the front for easy access like a patch bay. The components I used were from things I just had at hand. For example the 10K pots are linear pots but I would of preferred to use log pots if I had them. I'm sure that the design could be a little different but I just kind of stumbled through it from scratch and it works really good. With the volume controls on full the output is about 3-6 db louder then the input which gives a little leeway for whatever the need.

The target of this project was the design of a small portable mixer supplied by a 9V PP3 battery, keeping high quality performance. The mixer is formed assembling three main modules that can be varied in number and/or disposition to suit everyone needs.

You can setup the mixer by hooking potentiometers between 5V and Ground, and the wipers to the inputs. The mixing ratio, and balance can then be roughly adjusted, using a voltmeter, and the unit tested, before installing the unit in the Transmitter. Space can sometimes be at a premium, so mount the mixer carefuly. The LM3900 is a single supply, Quad Operational Amplifier.

In its simplest form, a voice-over unit is just a microphone and change-over switch feeding an amplifier, the output from the microphone having priority over the amplifiers audio signal when the "push-to-talk" switch is pressed. In this circuit, a preamplifier immediately follows the microphone and is designed to be used some distance away from the main amplifier. The changeover switch is nothing more than a relay with a single changeover contact. For completion, an amplifier based on the LM380 is shown. Three wires are needed to connect the remote microphone unit to the amplifier and switching unit.

One of my most ambitious projects, this mixer was made for my friends Tony and Wilfred of Mixed Fruit Jam as a practice amp. It's a relatively straightforward design, and will probably not be the best way of doing this. However, it works fairly well, and is relatively inexpensive to build.

This project is probably the most ambitious so far, and can be expected to be very expensive. On the positive side, it is also capable of excellent performance, and can be tailored to suit your exact specifications. There are several different input modules in the series, the first being the microphone and line input. The project is presented in parts, and Part 1 shows the mic/line module and has some background information on noise measurements and the general philosophy behind the project. Stages 2 and 3 are now complete, and are described below, and Stage 4 is available, but still under construction.

This simple circuit mixes two or more channels into one channel (eg. stereo into mono). The circuit can mix as many or as few channels as you like and consumes very little power. The mixer is shown with two inputs, but you can add as many as you want by just duplicating the "sections" which are clearly visible on the schematic.

This relatively simple mixer was designed for three dynamic microphones, but can be re-designed for more or less. Level and tone controls are available to tailor the sound to your needs.

With this circuit you can mix four separate audio inputs. Each input will accept high or low impedance microphones, phonograph, tape or aux signals. You can adjust the gain of each input by adjusting each respective pot. With the Stereo/Mono switch you can combine just inputs 1,2 and 3,4 or in the Mono position combine all four inputs. Signal response is 20 Hz. to 20kHz. with very high input impedance and very low distortion with complete output short circuit protection. This circuit will drive any power amp with an input impedance of 2,000 ohms.

Description is not in English language.

The circuit is suitable to be uses as a mixer between two line level sources and one HIFI amplifier input. This circuit have been successfully used for mixing signals form two CD players or computer soundcard and CD players. There are many situations where simple mixer would be useful and commercially available mixer desks are too expensive and big.

This is an image Schematic. No Description available.

If two of these circuits are made in the same enclosure for stereo, then there can be a single power supply to run both of them. There should be a resistor in series with the incoming 9V+ lead so as to minimize crosstalk, and reduce the PLOP when it's powered on. Other features can be added to this basic mixer. One or more microphone preamps could be added. A VU level meter or LED bargraph can be added. The microphone preamps could have a transformer to match a low impedance microphone to the preamp input. Etc...

This is an image Schematic. No Description available.

This is an image Schematic. No Description available.

This is an image Schematic. No Description available.

The target of this project was the design of a small portable mixer supplied by a 9V PP3 battery, keeping high quality performance. The mixer is formed assembling three main modules that can be varied in number and/or disposition to suit everyone needs.