I am part of dance music production team. We do get club and radio play and, in the case of the latter, as far as I'm aware this will often mean mono playback. So I am always careful when mixing down a track that it sounds similar in mono to the stereo mix.
I have compared our mixes with others in our genre and, as you'd expect, our mixes sound better than some and not as good as others, but even in the ones which I regard as better than ours, there seems to be something which separates the great mixes from the good ones: the really good ones sound big in stereo and in mono.
I've been comparing two such records, and both sound massive in the studio compared with our mixes but when you press the mono button, on one it disappears, and when you press it on the other it doesn't change one bit! How do they do it?
SOS Forum Post
Technical Editor Hugh Robjohns replies: Mono mixes will always sound different to stereo ones, and there is little that you can do about that. On a technical level, the mono mix contains only the 'mid' information whereas the stereo mix has both 'mid' and 'side' information.
The reason a stereo mix 'sounds massive' is because of the quantity and nature of the side signal. If there is a lot of out-of-phase information in the stereo mix it will tend to sound very big, but this information will largely be lost when listening to the mid signal only.
The trick is to make the mix sound 'big' in mono, and not rely too heavily on the side signal. One element of this is the careful choice of reverbs and delays, making sure that they sound suitably big in mono before checking in stereo.
It is very educational to listen to the return from a variety of reverb processors and compare the sound in both stereo and mono. Some all but disappear, basically because the left and right channels are extremely 'decorrelated' — the processor is relying on phase differences to create the effect — while others remain far more credible. I think this is where you will find the main difference.