To maximize gain before feedback on stage you must place and aim your stage monitors for maximum microphone rejection. The more precise your aim, the more gain before feedback you can get out of the system.
Aim the stage monitor at the null point of the microphone for up to 20dB of rejection for a fun show instead of a feedback nightmare.
For example, imagine that you are using a common supercardioid microphone like the Shure Beta87A. You eyeball the placement and aim and hope for the best. It’s more likely that you will be slightly off than dead on.
So what if you are slightly off?
If will be different with every microphone, but if we look at the polar pattern of the Beta87A, we can see that an error of 30º could cost you 5dB. At first, 5dB may not seem like much, but think back to every time a vocalist has begged you for a tiny bit more vocal in the monitor. Maybe you could have given it to them if you had aimed dead on.
How do we aim more precisely?
- Find the polar pattern of your mic.
- Buy a Polar Pointer from Rat Sound.
- Place the stage monitors at the laser dots and aim them at the laser origin.
- Print out my aiming triangles business card.
- Use your own laser to point out the optimum position.
Look up the polar pattern for your microphone.
The null point angles I found for supercardioid and hypercardioid were 125º and 110º from Dave Rat, which I assume is what he used in the polar pointer and is the reason for the updates I made to the aiming triangles business card. That being said, I could not find a manufacturer that actually followed that.
We already discussed the Shure Beta57A, which claims to be supercardioid with null points at 120º. I also found the Beyerdynamic M201, which claims to be hypercardioid with null points at 120º.
We can’t make assumptions. We have to know our microphones. Maybe someone should create big database we can reference with all of the null point angles for every microphone. Maybe I should do it? Maybe it exists already?
Here’s a chart from the Shure website. As you can see, it disagrees with the Rat Sound Polar Pointer.
Check the pattern all the way around
From Dave Rat’s blog:
If you point a cardioid mic parallel to the ground it is impossible to get a floor wedge in it’s rejection zone! Furthermore, to optimize wedges for the rejection zones of super and hyper cardioid mics you will find the wedges either need to be surprisingly far apart or your mic will need to be pointed at a fairly severe upward angle.
This 3D image of a supercardioid pickup pattern should help.