A mixing console has multiple outputs designed for specific functions. Two of the outputs on mixing consoles are the Sub Out and Main Out ports. Having relevant knowledge of the specific functions of these two outputs is ideal for getting the best from any mixing console you lay your hands on.
Therefore, if you have little to no idea about the roles Sub Outs and Main Out ports play in a mixing console, then you need to read this article.
The Main Out on any mixing console is the primary audio output of the mixer. It is meant for sending audio to the main speakers or front-of-house (FOH) system. On the other hand, a Sub Out is designed to output a secondary mix and is meant for sending audio elsewhere other than the front-of-house system.
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What Is A Sub Out?
There are two types of sub output (or sub out) found on audio devices and they are completely different when it comes to their functionality. The first type is found on mixing consoles and keyboard workstations. And the other is found on A/V stereo receivers.
Sub Outputs on mixing consoles and keyboards are ports that are primarily designed to output a sub or secondary mix. What this means is, the Sub Outs are meant for sending audio elsewhere other than the main speakers or the front-of-house system.
One thing you should note is that most mixing consoles typically have a number of Sub Out ports of their own. A mixer’s Sub Outputs can be used to group together specific channels on the mixer, such as multiple backing vocal microphones.
On keyboard workstations, sub out can be used to send different set of sounds while the Main Out sends another different set of sounds. It can also be used to send tempo clicks for band members.
Keyboards like the Roland Fantom-0 (which I use in my church), Korg Kronos, and many other workstations have sub outputs
Sub Outs can also be used to send a full mix from the mixer to an external device other than the main speakers or stage monitors.
In addition to the above, the functionality of Sub Outs also enables audio engineers to create an FX return channel for sending signals to the mixer’s effects processor. This allows users to add effects to output without affecting the audio in the main mix or monitor mix.
All of these highlight the fact that Sub Outs are exceptionally useful when there is the need to send audio to stage monitors or a separate part of a building. They also prove to be valuable when you need to record or monitor the main mix with headphones.
As I mentioned earlier, the second type of sub output is found on A/V stereo receivers and they work completely different from the ones found on mixers and keyboards.
Sub outs on receivers are designed to output only the low frequencies in an audio. It is meant to be connected to a subwoofer. I’ve talked about this type of sub out several types on this blog. And if you want to learn more, check out this article I wrote.
What Is A Main Out?
A Main Out is the commonest output found on an audio mixer. This output serves as the primary signal output of mixing consoles. Due to this, most people are of the view that Main Out ports are the most important ports in every mixing console.
In most mixing consoles, a Main Out is available as right and left Main Outputs. These left and right Main Outputs are where all the mixing console’s input channels are routed. In general, every mixing console comes with a master fader that controls the sound level of the Main Out.
A Main Out transmits the most amplified and clearest signal from mixing consoles. Due to this, audio signals from Main Out ports are the most usable signals from mixing consoles. This audio output is affected by all EQ, gain, mixing, and effects that are applied to it.
Unlike the “Sub Out” that is found in both mixing consoles and A/V receivers, a “Main Out” port is found in only mixing consoles.
In summary, the Main Out of any mixing console is the primary audio output of the console. That is why it is treated as the go-to output by users.
A Main Out is typically meant for sending audio to a front-of-house system or to another external audio projector, such as a speaker system. However, a Main Out can also be used to send audio to a recording surface.
That notwithstanding, when it comes to recording, a Rec Out port will do a much better job than a Main Out port. To find out why this is the case, read this article.
What Is the Difference Between Sub Out and Main Out?
If you have taken time out to critically observe audio equipment, you would realize that most modern mixing consoles have Sub Out(s) as well as a Main Out port. Having an understanding of the differences between Sub Out and Main Out outputs will prove valuable to anyone who uses mixing consoles regularly.
The primary difference between a Main Out and a Sub Out is that the Main Out serves as the primary audio sender of a mixer and provides a full mix audio output to the front-of-house. On the other hand, a Sub Out serves as a secondary output or a way to group channel.
Due to the fact that a Sub Out is a secondary output, it is designed to provide a mix of selected channels to non-FOH sources. What this means is, Sub Outs always have a separate function and are not usually used to send audio to the main speakers.
With a Sub Out, you are capable of outputting only the channels that you choose. Thus if you have two leading microphones and four backing vocalists all plugging into your mixing console, you can choose to output only the leading mics through a particular Sub Out channel.
Another difference between the two is that all Main Out ports are high-quality stereo outputs audio, while Sub Outs may not always be stereo. That is why Sub Outs are often better suited for sending audio elsewhere other than the front-of-house system.
To end it all, a Sub Out is meant for channel grouping or for use as an external send whiles the Main Out will always be the source of the audio used for front-of-house.
Similarities Between a Sub Out and a Main Out
If you have read up to this point, then you must have definitely noticed that there are a lot of differences between the Sub Out and the Main Out ports. Even though that is the reality, these two mixing console outputs share a few similarities between them. Let’s take a look at them briefly.
The first point to note is, both Sub Out, and Main Out ports are affected by gain, EQ, and other effects that are applied to them.
In fact, unless your mixing console’s soundboard gives you room to choose, every mixer Sub Out originally comes as post-EQ. This means Sub Outs have their audio signal source at the point where EQ has already been applied.
Another point is, just as Main Outs are designed to have a master fader for controlling audio levels or volume, mixing console Sub Outs come with a master level control of their own.
This master-level controller is used to regulate their overall output volume. It allows users to turn the entire mix up or down without having to change the individual channel volumes.
In digital mixing consoles, Sub Out master volume level controllers come as faders. However, most analog mixing consoles have their Sub Out master volume controllers being knobs.
Conclusion
A Main Out is always the primary output of a mixing console and always has the strongest, most useable output signal from the device. That is why a Main Out always serves as the source of audio used for the front-of-house mix. Whiles Main Outs serve as the primary output of mixing consoles, a Sub Out on a mixer serves as a secondary output or external sends, as well as a way to group channels.
Hello, I’m Elijah. A writer on Geek Musician, based in Ghana-West Africa. I am a writer with a passion for research and reading. I usually spend my free time playing chess or watching movies. For more info, check out my about me page. Or read more of my articles here.