Inserts vs. Auxiliary sends

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Inserts vs. Auxiliary sends
Published in: Season 3 - Mixing

In todays tutorial we’re looking at the difference between the usage of AUX- effects and insert-effects. -First we’ll look at what Insert FX and AUX effects actually do, to understand why we would use them.
Let’s first look at the signal-flow for both the insert-effects and aux-effects.


We usually have an insert for each track on the mixer. (For software mixers we can usually find around 10 insert-slots as these work a bit different.)

On the insert point on an analogue console  the signal physically leaves the channel-strip and the console to run through an external processor. -So the insert point is an actual break in the signal-path.  We can use inserts to run the full signal on that channel through a compressor for example. -Simply said we use an insert for processing through an external processor for just that specific channel.

Insert - Send / -Return.

In the analogue world we talk about an insert send and insert return. The insert send is the output, the insert return is the input of the send. A simple way to remember this is that we SEND the signal to the processor, and we RETURN it to the console after processing. 

Higher end consoles might have an actual send and return connector for each channel, while other mixers might have merged the send and return in to one physical connector to save space and cost. In that case we can use an Y-cable to connect the send and return paths over one connector. These Y-cables are soldered in a way that they to use the TIP for the send and the RING for the return.

'If we want to use several inserts on one channel, how is that possible?'

Thats fairly simple, route the signal from the insert-send point to the input of the first effect, lets say that is a gate. we run the output of the gate to the input of the next processor and so on. The output of the last processor in the chain is connected back to the insert-return.

Aux send.

An Aux send sends a portion of the signal on a channel to an Aux-bus. 
The aux-bus can be seen as a horizontal connection on the mixing console. Every channel that we wish to can send a portion of it’s signal to feed this auxiliary-bus. 

The output of the auxiliary bus is usually a physical output on the back, or top, of the console. From here we can send the signal to a fx-processor like a reverb unit. The output of the reverb unit can than be send to a group return on the console, or to two spare channels. 

In sofware the ‘digital aux’ simply contains slots to put our effects in. We can there simply route the output of the aux-bus to the mix-bus, or any available group-busses if desired. The concept of auxiliary-sends is still the same here though.

So when would I use an insert effect, and when would I use an aux-send?

When there is channel specific processing like compression, gating, equalizing, or chorus-effects that we want to affect our whole sound with we use an insert effect. If there are effects that we want to use on many channels, like a reverb or a delay we can use an aux-send so we can send a portion of the signal to the reverb unit. We keep having the original signal un-changed in the mix and we add in the effect on a different channel.

Wet / dry mix.

When we use an auxiliary send we only send a portion of the channel to an effects processor. This means we can blend in this effect with the mix and create a wet/dry balance between the original signal and the affected signal. Dry is what we call the unaffected signal, and wet is what we call the affected signal. 

Many processors like dynamic enhancers and equalizers are often used as a 100% wet signal where we want the full signal to be treated, we usually don't want 50% gated kick drum blended in with 50% of the original signal. as that kinda defeats its purpose. 

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Wick van den Belt

Besides that Wick has started WickieMedia, he is also author, blogger and video-editor for the site.
Wick is very passionate about audio engineering, music production, graphic design, motion graphics and good cappuchino.

Wick is the author of 'Audio Engineering - Dynamic Processing' and 'Audio Engineering - Spectral Processing'.
You can find both titles in the iBookstore. 


Website: www.wickiemedia.net

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