Radial MIX 2:1 User Guide
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Using The MIX 2:1™

The MIX 2:1 is a simple passive mixer that sums two audio signals together cleanly and easily. This page provides an overview of the various features of the MIX 2:1, for further details please click on the icon to the left to download the user guide.


The MIX 2:1 is a simple summing mixer that makes merging two audio signals easy. Whether you need to sum mic or line level signals, or the outputs of two separate devices, the MIX 2:1 allows you to do so without noise or coloration of the sound. XLR and ¼" TRS inputs are provided for easy connectivity, with a single XLR output to feed your destination device. Level controls are available for each input, or they can be bypassed entirely to sum the left and right outputs of a mixing console or recording interface equally. A 180° polarity inversion switch opens up other options such as summing a snare top and bottom mic together to a single preamp, and ground lift switches help eliminate buzz and hum from ground loops.

Before making connections, ensure that your sound system is turned off and all volume controls are turned down. This prevents any plug-in transients from damaging speakers or other sensitive components. The MIX 2:1 is passive, and doesn’t require any power to operate. Each input has a ¼" TRS and an XLR connector to accept balanced mic or line-level signals. For best results, only use one of these connector types at a time on each channel. The XLR output of the MIX 2:1 will also be mic or line-level depending on your input sources and the amount of attenuation applied using the input trim controls. Keep in mind that the MIX 2:1 does not provide any gain to the input signal, so if you connect two microphones to its inputs you will still need to feed the output into a microphone preamp to boost the signal to line level.

Summing a stereo source to mono

With the MIX 2:1, you can quickly take a stereo feed from a mixing console or a recording interface and sum it to mono to feed a single speaker input on a PA system. Push in the ON buttons for both inputs so they are both active. Next, engage the recessed LEVEL CONTROL BYPASS switch on the right hand side of the MIX 2:1 – this will disable the input level controls for each channel, to ensure equal summing.

The MIX 2:1 will automatically compensate for the 6dB in voltage gain that occurs when two in-phase signals are summed together, so you won’t distort the inputs of your destination device. Should you need to attenuate the levels, simply disengage the LEVEL CONTROL BYPASS and adjust each level control until you achieve the desired results.

Summing two seperate sources

The MIX 2:1 is also handy for summing audio signals from two different devices, such as a guitar mic and a passive DI, or top and bottom snare drum mics. When summing two separate sources, start with the input level controls fully clockwise (max) and use the ON switches to audition each channel individually. If one signal is significantly louder than the other, use the level control on that channel to achieve the desired balance between the two signals.

Using the 180° switch

The MIX 2:1 includes a 180° switch which flips the polarity of the audio on INPUT-2 - this is sometimes referred to as a ‘phase reverse’. When two audio signals have similar content but are reversed in polarity, certain frequencies can be cancelled or amplified when the signals are summed together, creating a filtered or unnatural sounding result. The 180° switch can be a quick way to reverse this effect and bring the signals back in alignment with each other, resulting in a fuller and more balanced sound.

Using the ground lift

When connecting two or more powered devices to each other, you may encounter hum and buzz caused by ground loops. The MIX 2:1 is equipped with ground lift switches on both inputs; these disconnect pin-1 on the input connectors to break the electrical ground path and remove the noise. If you experience any hum or buzz when using the MIX 2:1, simply engage these ground lifts to help eliminate the problem.