The idea of a mix ‘glue’ is usually applied to the use of dynamics processors, as with the various ‘glue compressor’ plugins. Gluing in the common usage aims to get the multitude of sonic elements in a mix to cohere by rounding out their envelopes in a similar manner as they all hit the same compressor’s threshold. A reverb applied to an entire mix or stem can also have ‘gluey’ effects as all the sounds that pass through it take on similar spatial characteristics.
This short article details what can be called variously ‘harmonic gluing,’ ‘timbral gluing’ or even ‘spectral gluing.’ While drones can be of any length and don’t need to reference the song’s metrical structure, the technique shown here is to take a rich, complex and evolving drone sound pitched to the tonic and timed to 8 measures, since most melodic units are 8 bars long. In the banner image above, you can see two glue drones in the bottom tracks laid out for an entire song, in light grey. My harmonic glue drones often get placed into the mix last, hence their appealing track names ‘Misc 1’ and ‘Misc 2’! Melodies, meanwhile, get the pretentious Greek treatment and are labelled melos. This is probably very unfair to drones.
In this song (it’s an instrumental but I still call them songs, since that’s a shorter word), there are two alternating complex drones — not the most complex in their timbres, but rich enough to get the job done — that run throughout the entire piece. The drones start anew every 8 bars, so that some listener familiarity sets in with the occasional textures that poke through the other mix elements. The two drones take turns in different parts of the song to support a sense of sectional divisions. Here are the two 8-bar drone elements in isolation from the mix.
One nifty trick with having an ever-present glue drone is that you can chop off sections of the chord progression so that the rich harmonic glues can be heard popping through the mix intermittently. Below, the last two bars of the 8-bar chord progression pattern have been clipped with each recurrence, leaving 2 bars at the end of the pattern without chord progression texture for the drone to display some of its magic.
You can hear the glue drones discussed in this article in the music video below.