Understanding Real Time Analysis

With all analyzers you should carefully listen to the room/system with some music you know very well, using your highest quality analyzers (your two ears) and use that to decide what is wrong with the room. I use a mix of classical, rock and jazz recordings to test a system. This helps to keep a balanced perspective about the room and the system, the goal is to make them all sound good when you are through. After you have a clear mental picture of what you believe is going on, only then should you start checking with an analyzer. You ears will always tell you more then any piece of test gear.

I only use RTA's to setup sound systems, many poeple find a RTA to have little use in setting up a control room. It is not recommended to ever eq nearfields. A 1/3 octave RTA can only show gross problems in a system or a room.

When using an RTA many people try to eq the room to be as flat of a RTA reading as possible. However when they do that they can't understand why it didn't work. The problem is if you eq the room to be flat on an RTA the result will be excessive high frequencies and a weak bass response.

What you want is slight bass bump of 2-3dB up to around 100-130 Hz and then the highs should start to roll off around 7-8khz. Most systems will start to have a bass roll off at around 40-60 Hz, don't try to push it up, that is the natural speaker roll off. Pushing the bass up will just use more amp power and you might damage the speakers, since you would be pushing them beyond what they were designed to do.

Below is a screenshot of the spectrafoo 1/3 octave RTA to show what you would want to see on a RTA. The main thing to look for is a frequency area that is spiking up or dipping down. Then you may need to cut or boost that frequency.

 

On bi-amped or tri-amped systems you should adjust the crossover to get a RTA reading close to the desired curve, and use the eq to fix any small problem areas. If you can't get it close with the crossover, something is wrong, and you should check for equipment or wiring problems.