We briefly ran into the ADK A-48 Vintage Valve microphone the other day and took note of its no fewer than NINE polar patterns.
Er, we can't even name nine polar patterns. The familiar ones are these…
If you look more deeply you might find mention of the subcardioid pattern. That's the one that's a little more equally sensitive all round than the cardioid, but not as much so as the omnidirectional pattern.
There is the shotgun pattern too, but this falls outside the normal spectrum of polar patterns so we'll leave this for now.
So why do we need all these different polar patterns?
Well firstly, remember that there is in reality a continuous spectrum of patterns between omnidirectional and figure-of-eight.
As we traverse this spectrum at first the sensitivity to the rear decreases, then disappears. Then the front sensitivity narrows. But as that happens, sensitivity to the rear reappears and nulls in the response are created at the rear sides. Gradually the rear response becomes as strong as the front, and the nulls move directly to the sides. We now have figure-of-eight.
There is a huge difference between the opposite ends of the polar response spectrum. A true omnidirectional microphone can't be pointed. Well you can try, but it will always sound the same whatever direction it is pointed.
A figure-of-eight microphone is very sensitive to direction. You have to point it precisely, but that gives you more control. With a pair of such microphones, you can exploit their directional properties to create a stereo recording from two mics very close together but pointed apart.
In practice you will find big differences going from omni to cardioid, and cardioid to figure-of-eight.
Also there are times when you will want something a little more 'pointy' than a cardioid, but you don't want the full rear sensitivity of the figure-of-eight. A supercardioid or hypercardioid will do nicely.
But are there times when you would choose a supercardioid and other times when you would choose a hypercardioid?
Well if you really can hear the difference between these patterns in actual use, then you have keen ears indeed.
So going back to the nine polar patterns of the ADK A-48 Vintage Valve, you don't really get more polar patterns than a mic that just has omni, figure-of-eight and two patterns in-between. What you get is a finer gradation of patterns between the extremes.
In fact, it is perfectly possible to make the pattern control of a microphone continuously variable rather than switched, so you have an infinite range of polar patterns!
In practice, four patterns will do just fine. But we're in this business because we love it and sometimes we just want to play!