Delta solo offers a really useful way to hear what processing is doing, however it is provided in only a handful of audio tools. We show how it can be used on any plugin in any DAW, with the tools you already have.
While engineers spend a lot of time deliberating over effects and processing in the mix, many who have flattened a mix and started again would concede that some mixes are like a maze. That is to say there’s a lot of potential to get lost in there but there’s usually only one way out! That said, aside from getting the fundamental levels right in a mix, when it comes to audio processing and effects, the engineer will use several different methods to answer the perennial question: are changes making the mix better, or just different?
Judgement Calls
Of all the methods hoping to answer that question, perhaps the best known function is Bypass, be it in the tool itself, or provided in the DAW. Whatever bypass reveals (in the context of Better Or Different) the point of it is to provide an instant, binary basis for comparison.
On more subjective ground, other techniques for judging the amount or type of treatment to use can involve deliberately introducing more than intended to hear the result, before backing off to an appropriate level. This can work especially well on the understanding that using solo to hear channels’ processing removes the idea of context.
What Is Delta Solo?
A small number of audio plugins land with a Delta Solo button, with some DAWs’ stock tools featuring them across the board. This function allows the engineer to hear only the difference between processed and unprocessed audio. Examples would include hearing only the chopped-off peaks from limiting, or a cut frequency notched out of an otherwise great sound. That said, delta solo remains an expensive luxury for many users of audio plugins with provision found mainly with third party solutions.
In the video, we show how delta solo can be achieved even with audio plugins that do not provide it. We listen for the optimum cut band on a bass, before using delta as an alternative to dialling dry signals out of reverb treatments to really hear what the reverb settings are doing. Delta solo is then used on vocals as the ultimate tool for hearing unwanted audio compression artefacts.
Using difference techniques in this way can provide a useful alternative way to shine a light on mix decisions; of course the answer to Better Or Different in context is, for the time being, one that the engineer themself must decide. While delta solo remains less common in stock and third party solutions, the engineer can still get the delta experience on any platform with a little thought.