What is Mix Minus and How Does it Work

Mix Minus is a technique used to create a clean audio signal for live broadcasts, such as TV shows or concerts, by subtracting the audio of the broadcast itself from the main audio feed.

This allows the broadcast to be mixed and mastered without the audio of the broadcast being picked up and creating echo or feedback.

A common application of Mix Minus is in live TV broadcasts, where the audio of the broadcast is being sent to a satellite or cable provider, and the audio of the broadcast is also being played back in the studio or at the venue.

Mix Minus is used to prevent the audio of the broadcast from being picked up by microphones and creating echo or feedback.

Consider reading: Onn Roku Tv No Picture but Sound

A Mix Minus signal is a special audio signal designed to avoid feedback and echo in conference or telephone interface applications.

It's a full programme mix minus one contributing source, typically used in broadcast applications where remote contributors need to hear all other sources but not their own contribution.

The idea is to prevent howlrounds and confusion due to transmission delays, and each remote contributor needs to receive its own independently generated Mix Minus signal.

Mix Minus can be generated by sending the full programme mix with a second version of the remote contributor's signal added in opposite polarity, cancelling out the remote contribution.

Alternatively, it can be achieved using an Aux bus that receives contributions from every source except the remote contributor, known as 'N-1' or 'Clean-feed'.

A Mix Minus signal is an audio signal carefully designed to avoid feedback and echo in conference or telephone interface applications.

To create a Mix Minus signal, you must not send the same mix that you're playing over the PA system to the phone participant.

The solution is to create a special mix to send to the phone link, known as a "Mix" of the two microphones, "Minus" the phone participant.

This rule applies to both simple and advanced applications, including conferences and support calls.

In a digital hybrid phone line interface, the digital hybrid will prevent the two microphones from echoing back through the phone line, but it's still possible to inadvertently mix the caller's voice back into the transmit mix.

If you send the same mix to the phone participant, you'll complete a circle of audio from the caller back to the caller, which is a potential source of feedback and annoying echo.

A Mix Minus signal can be generated in several different ways, but one technique is to send the full programme mix with a second version of the remote contributor's signal added in opposite polarity, thus cancelling out the remote contribution.

If this caught your attention, see: S Band

A 'Mix-minus' is, as the term implies, a full programme mix but with one contributing source missing from the mix. This is most commonly used in broadcast applications.

The idea behind Mix-Minus is to allow remote contributors to hear all other sources being mixed into the programme, while preventing them from receiving their own contribution coming back, which can result in howlrounds and confusion due to transmission delays.

In programmes involving multiple remote contributors, each would need to receive its own independently generated Mix-Minus signal.

A Mix-Minus signal can be generated in several different ways, but one technique is to send the remote contributor the full programme mix with a second version of the remote contributor's signal added in opposite polarity, thus cancelling out the remote contribution.

Another technique is to use the equivalent of an Aux bus which receives contributions from every source except the remote contributor, known as 'N-1' or 'Clean-feed'.

The goal of Mix-Minus is to prevent echo and feedback, and to ensure a clean and clear audio signal for remote contributors.

Using a digital hybrid phone line interface can prevent the two microphones from echoing back through the phone line, and returning mixed with the caller's audio.

Mix-Minus may sound complicated, but it's really just a simple rule: don't send caller audio back to the caller.

Intriguing read: Mix Mr Clean

Setting up mix minus can be a bit tricky, but it's a crucial step in preventing feedback and echo in conference or telephone interface applications. The key is to create a special mix that sends the caller's audio to the phone participant, minus their own voice.

You'll need to use a mixer or audio interface to create this mix minus signal. For example, if you're using a mixer, you can connect the main outputs to the inputs on the livestream audio interface, and then use the channel faders to send the remote guest's audio to the main mix. But to prevent echo, you'll need to set up a separate mix for the guest, using an Aux output on the mixer to create a mix-minus for them.

Some audio interfaces, like the RME TotalMix, have built-in virtual mixing and matrixing capabilities that can simplify the setup process. On Mac, you can use software like LadioCast and Blackhole to create a mix-minus signal, but be aware that this can be a bit more complicated and may require additional setup.

To set up mix minus on a mixer, you'll need to create a mix that excludes the remote guest's audio. This is done by using an Aux output on the mixer to create a mix-minus for the guest.

Connect Aux Output 1 on the mixer to input 1 on the Zoom audio interface. You'll then select this as the audio input within Zoom.

Decide what goes to that mix using the Aux 1 sends on each channel. For example, you can send the two in-room microphone channels to Aux 1, but NOT the Zoom guest channel. This creates a complete mix, minus the remote guest.

Using this setup, the remote guest can now hear the in-room microphones, but not their own audio, which prevents echo.

To set up RME TotalMix on Windows, you'll need to install the software first. Download and install the latest version of TotalMix from the RME website.

RME TotalMix is a powerful mixing and routing system that allows you to configure your audio setup. It's available for Windows and Mac, but we're focusing on the Windows version here.

To get started, launch TotalMix and create a new configuration by clicking on the "New" button. This will give you a clean slate to work with.

In the main window, you'll see a list of available inputs and outputs. You can use the "Input" and "Output" buttons to configure your audio setup. For example, if you're using a USB audio interface, you might see it listed as "USB Audio Interface" under the "Input" tab.

To set up your audio interface, select it from the list and click on the "Configure" button. This will open a new window where you can adjust settings such as sample rate, bit depth, and buffer size.

Related reading: List of Communication Satellite Companies

To set up mix minus on RME TotalMix on a Mac, you'll need to download two free software pieces: LadioCast and Blackhole. This will help you work around the limitations of Mac OS.

First, install LadioCast and Blackhole, and then use the loopback feature to route your in-room microphones to the main mix. This will allow you to hear both the in-person mics and the remote Zoom guest.

Next, set the Zoom audio output to the audio interface, which corresponds to software output 1 and 2 within Totalmix. This is already being used for your main mix, so you'll need another mix to set up a mix-minus for the Zoom guest.

Blackhole acts as a virtual input to Zoom when you select it as the microphone source, and LadioCast can route things to Blackhole using the RME interface as Input 1. Select the channels you want to use, such as 3 and 4, and use the loopback button on output 3 and 4 to feed these input channels with a custom mix-minus.

To finish setting up the mix-minus, send the in-room mics only to that mix-minus mix, and then send that to the Main output, which is BlackHole.

A unique perspective: Xiaomi MIX 4

To configure mix-minus, you'll need to connect a 2-in/2-out audio interface to each laptop, one for streaming to YouTube and one for hosting the Zoom call. This will make it easy to get audio in and out of each laptop.

The main mix for the YouTube livestream audience is set up by connecting the main outputs on the mixer to the inputs on the livestream audio interface. You can decide what's sent to this mix using the faders on each input channel.

Within the livestream computer, ensure the audio interface connected to it is selected as the audio input device within YouTube. This will allow the audio from the mixer to be sent to the livestream.

To get the audio from the remote guest into your system, select the interface connected to the Zoom laptop as the output device within Zoom. This will send the remote guest's audio out of output 1 and 2 on that interface, which you'll connect to stereo input 7 and 8 on the mixer.

Worth a look: How to Pair Soundcore Liberty Air 2

Using an Aux output on the mixer creates a mix-minus for the guest. Connect Aux Output 1 on the mixer to input 1 on the Zoom audio interface and select this as the audio input within Zoom. Decide what goes to that mix using the Aux 1 sends on each channel.

You can use a more advanced audio interface to do this with one computer, but for now, let's stick with two separate laptops and a mixer.

Expand your knowledge: Serial Digital Interface

Mix-minus is a crucial aspect of sound reinforcement and conferencing applications, and understanding its best practices and applications can make all the difference in ensuring clear and feedback-free audio.

Designing a mix-minus system is essential to prevent feedback, especially in large spaces where participants are physically distant.

The primary reason for mix-minus design is to prevent feedback in conferencing or sound reinforcement applications.

In a sound reinforcement scenario, the mix of audio playing from the loudspeaker closest to the presenter should not include his own speech.

Loudspeakers are always on but do not carry signal from every source in the system – only the ones that would be difficult to hear otherwise.

Mastering mix-minus will allow you to take advantage of the efficiencies and convenience of current DSP products that combine auto-mixing, attenuation, and routing in a single “box.”

Here are four key best practices for mix-minus success:

A six zone mix-minus configuration example illustrates the importance of designing a system that takes into account the proximity of microphones and loudspeakers.

In this example, Zone 1 receives a mix of all microphones minus the Zone 1 mic, enabling all participants to hear each other clearly without feedback.