Such a long long time ago, the whipendale studio management programme
Most of the talent travelled from Leeds, Manchester perhaps the midlands, here is the acapella from the Anita Ward cover "Ring My Bell"
If i remember it right the Producer was Ron Wubry, we chatted in the annex for hours before the vocalist arrived (traffic) the MC from DJ Jamie Richards (Ealing Broadway Boulevard) Glenn came and added a few lines a cool cat but the song refused to deliver its magic and its stayed 'in the can'
So you've recorded a trio or quartet and the low part of the mix needs an extra smoothness or contains long notes requiring an extra effect to perc up the interest down there or its a smoking hot reggae dub & you want to do something out of the ordinary , a Levi Stubbs motown groove, etc the list goes on and on.
Anyhow whilst we tap out possible genre's of mix or crack up listing them, lets just presume you are going to add chorus to a low end instrument and you are faced with two options, mono or mono to stereo chorus.
Nine out of Ten clients choose stereo if i ask them which kind of chorus they would like. Citing " it's wider, its bigger and stereo has been better than mono since 1960's " All of which is true in some respects but the stereo effect should be used with caution on lower end instruments due to phase coherence.
If you imagine one large speaker and two medium speakers, the sum of the 1 large is equal to the 2 medium.
Brill, now imagine a single bass note played on both set up's. If the 2 medium speakers are not set exactly in the right place the sound waves that emit from the speakers will not 'scan' correctly within the mix/control room and frequencies will be cancelled out causing troughs and peaks within the replayed notes.
The large 1 speaker only has to play its low note and it is correct. The problem of coherence is greater in the lower frequencies because the sound travels at a slower rate so the cancelling out part where the frequencies fight and reduce the 'weight' 'power' and 'strength' of the signal last longer.
In summary the lower part of the mix is best kept in mono for strength, coherence and the ability to replay the mix on incorrectly assembled systems with greater chances of sounding like the system was correctly set up.
Thats a lot of tech & i understand if you zoned out within the first few lines. The Detroit ' motor city ' motown sound is such a good example of great mono recording if your jonesing for simplicity, try an early Stevie Wonder recording, plenty of music. Then contrast it to a very elaborate recording such as 'Frankie goes to Hollywood' Two tribes. The high end is crystal clear in comparison to the early motor city recordings, but back down on the bass end its strong and coherent a great example.