Putting it all together: making your song "radio-ready"

In the context of the previously discussed concepts and tools, making your song "radio ready", means making your songs sound "good enough" on anything that can conceivably play it back.

Picture your song being played back on a transistor radio on a work site, on a cheap laptop with tinny speakers, in a car with exaggerated bass, on a high-end audio system with sub woofer, or on a poorly calibrated home theater system set to enhance voice dialog.

Each of these systems have their quirks, gaps, limitations or exaggerations when it comes to reproducing the full audible spectrum. For example, physics dictates that small speakers - as found in the transistor radio or the cheap laptop - will never be able to reproduce deep bass (and if someone tells you otherwise, you are being lied/marketed to).

Making your song sound "good enough" on all these devices, means that people listening through them can still discern all the important elements in your song, no matter the spectrum reproduction limitations of the device. That does not necessarily mean those elements will sound the same however; we are merely talking about the suggestion of their presence. The primary goal is for the musical information (e.g. your full composition/arrangement) to survive.

Before doing all this, however, ensure you have already used basic the side-chaining, ducking and FX mud avoidance outlined previously, to ensure your elements are getting the right attention in the mix at the right time ("temporal mixing"). When doing this, use a device you trust to give you a reasonable flat frequency response (e.g. good monitoring headphones or speakers that accurately represent every frequency equally). This makes your life a lot easier when your start to trouble shoot for specific devices, on your way to a "radio ready" mix.

E.g. free up the spectrum as much as possible first, based on what's playing in your song ("temporal mixing"), and only then start troubleshooting any elements that sound too loud or not loud enough on other devices.

Again, we note that the most expensive and "perfect" monitoring solution with a flat frequency response is still not a good indicator on how your song will be perceived on other devices. For example, a pure sine wave bass that sounds perfectly fine in your "perfect" monitoring solution, will fail to render completely on at least some devices in the real world.

"Suggestion" over actual presence

As touched upon discussing the "missing fundamental" techniques, the human brain is exceptionally good at filling in the blanks, as long as it has something to go by (for example a transient or higher harmonics). It is your job then to help the brain as much as possible using the tools and concepts discussed earlier.

Concretely, this means that - unless your genre specifically calls for, say, a strong sub-bass - you will want to avoid the situation where an element occupies just a single frequency in the audio spectrum (like the aforementioned sine wave); in such a case it is possible/likely to completely disappear or drowned out on at least some of these devices.

1. Listen and re-listen on as many devices as you can. Have a set of devices ready that you know well, and that you know have specific flaws that are representative of real-world situations (the tinny laptop speakers, the exaggerated bass car stereo, the missing mids of a poorly calibrated home theater system, etc.).
2. Make sure you can hear all your song's elements at least happening(!) on each and everyone of these systems.
3. If you cannot hear certain elements, use the tools at your disposal to make them stand out more. For example, shaping their transients (using the per-track compressor, adding a slight click or noise burst, etc.), or adding harmonics (open a low-pass filter slightly more, use a saw or square wave instead of a sine, use the aural exciter, use an EQ boost, etc.) or more strongly ducking other elements out of the way that may be overpowering the harmonics on that specific device (or as a last resort, use a permanent EQ cut for those competing elements if you really have to).
4. Re-listen to your song to confirm it still sounds good and appropriate on all other systems
5. Go to 1.

By the end of this process, you will have a track that conveys your song with all its elements across almost all possible playback devices; it will have become "radio-ready".