Reply To: Live Sound Engineering Tutor?

[Dick Rees]

I understand your situation: I was in the same position. I did two things:
1- took online training (free on youtube) on ringing out systems (how to EQ out the feedback frequencies)
2- I bought a DBX AFS2 for my monitors, and a DBX driverack PA2 (auto-EQ and anti-feedback) for front of house. Both do realtime feedback suppression !!! It’s easy magic.

It’s good to know the process and techniques for “ringing out”, but it’s more important to know what can and cannot be effectively addressed with such a procedure. I won’t go further with this particular issue right now, but suffice to say that “feedback frequencies” are not fixed as such and addressing them at one point in time will probably not hold over time. You CAN reduce the effect of room resonances/standing waves which ARE fixed phenomena, but you should only need to deal with 3 or 4 such.

As to “easy magic” stuff…NO. There is no magic, just physics. To use such devices/programs effectively, you MUST know how they work and how to apply the same techniques without the machine.

In addition, such things as “auto-EQ” and “anti-feedback” are like tourniquets, sutures and bandages. Better to prevent the problem in the first place with proper speaker selection/deployment and DSP. If your system is not optimized to begin with, applying EQ to it will be somewhat less than effective.

A friend sent me a screen shot of the filters set by the DRack “auto-EQ”. An uglier set of filters I have seldom seen with overlapping boosts and cuts. But the bottom line is this:

A machine does not know how it sounds..

Edit:

How many folks who report “I had a terrible problem at the gig last night” have ever taken time to set up their system and learn how to optimize it and experiment with what happens when you orient the speakers to focus on the listening area and minimize/eliminate reflections off the walls and ceiling? The same goes for monitors: placement in relation to the microphone polar patterns (nulls) and keeping spill off the back wall.

Take care to learn HOW to set up your gear in a room, don’t just throw it up, power it up and try and fix it with EQ or “magic”.

Buy and study the Yamaha Sound Reinforcement Handbook. You won’t understand it in the beginning, but when you have a problem and you look up the associated applicable phenomena in the book, it will dawn on you. I’ve had mine forever and it’s still great reading every time I pick it up.