Think back to your school science classes… did you ever experiment with a piece of apparatus known as a 'ripple tank'?
The ripple tank is a shallow, transparent tray with sloping edges containing water. It is mounted on legs above a table top, and illuminated from above the tank.
Inside the tank is a vibrating strip that produces waves, like waves in the sea but in miniature. The light source projects shadows of the waves beneath the tank.
With the ripple tank, you can easily observe the properties of waves, including diffraction.
To observe diffraction, place a solid object, let's say a rectangular object, in the path of the waves. You will see that although the waves are blocked, they spread out again once they have passed by the obstacle.
But you will notice something else… if the object has sharp corners, the trailing corners will act as sources in their own right, so each corner effectively becomes a wave generator.
Now, translate this to loudspeakers. The properties of sound as a wave are very similar to water waves.
You've guessed it, diffraction happens at the corners of the cabinet – the corners become sound radiators in their own right.
Clearly, this is bound to affect the sound field significantly. And if your monitors are not telling you exactly what is on your recording, then you are not in a position to make good judgments.
Because of this diffraction effect, it is absolutely wrong for a loudspeaker to have sharp corners. All loudspeakers should be smoothly curved, but how many are?
At least Genelec get it right and are an example to other loudspeaker manufacturers in this respect.
So if your monitors have sharp corners, get rid of them and invest in a pair of Genelecs, or other properly designed monitors. What sense is there in working with something that is so obviously wrong?
Oh by the way, not all Genelec monitors are curved. How come they only sometimes get it right?