What is "radio-quality"?... Many things:
- Radio quality could mean rolling off the bass from your song. Many plug-ins have that preset, which basically makes it sound like it's coming from a radio. ie "radio-quality".
- Radio quality could mean super-compressed sound. I think that this is mostly what you are refering to. Radio stations compress their material to make it sound as loud as possible by compressing it and limiting it. Compression to "squeeze" it, and limiting to make sure it doesn't go "over". Additionally, how well it's done varies greatly. I have heard horrible sound coming form radio stations, where the sound was so compressed, so "squeezed" that it was just un-listeneable. You would achieve that sound quality by running
hard a limiter or a compressor, preferably a multi-band one.
-Radio quality could also refer to the length of the song, in other words, it would refer to the quantitative quality of radio airplay. Around 2min 30 for pop music...But, there's no rule here either. For instance, a classical radio station would certainly not adhere to this time-limited rule.
-And, as it has been pointed out before, radio quality could imply that a song must be professionally mastered, ie radio stations only deal with "pro" quality songs coming form record companies and pro mastering studios. Of course, this is not always true. just look at many indie groups and radio stations who don't go through that path necessarily.
All of these things could be said to be part of what make a song "radio-quality". but the main point is that there is no precise definition of what is a "radio-quality" sound, or template to achieve it.
A.