ICEinLAVA's Domain

Okay, this time I’ll probably get all sorts of screaming e-mails from the tech departments of a dozen manufacturers, but such is the business of trying to squeeze a lot in to a short column. Experienced touring FOH guys, bear with me. I recently received an e-mail question from a reader who is a typical “sound guy” at a church in South Africa (now that’s circulation!). Could’ve been south L.A. or South Carolina: I have been asked the same basic questions a hundred times. Here goes...

“Is the goal of analyzing a room and correcting it with an EQ to get it ‘flat,’ or is the analysis purely for the engineer’s info in order for him to use the EQ to help him (or her) produce the sound character he would like to achieve in the room?”

Answer:

Yes, no, depends. First of all, I congratulate this reader on the ability to ask for help. That is the key to really learning about audio (humility, and lots of it).

It’s been my experience that using an RTA or other device to figure out what a room is doing can greatly improve the speed and accuracy of adjusting the system to fit the room. However, in a permanent installation with many of these measurements supposedly having been done before final install of the audio system, it becomes an excellent way to avoid much “tweaking” after the boxes are hung. At this point, these predetermined measurements can become a great guideline as to where to make the small fixes. I also have this odd theory for small and medium size installations: the carpet, walls, chairs, windows and speaker positions do not change by themselves and thus, once a room is defined acoustically, let it be done. Except for the completely anal-retentive guys who just have to have their LEDs wiggling and their laptops blipping every time the FOH console is turned on, most amateur/casual operators will get nothing but distracted from their real goal of providing a good live mix.

After all that, the goal should be having it sound intelligible, which I believe is far more measurable than simply saying, “it should sound good.” Getting a room “flat” may not actually sound the most pleasing to the ear, but for the less intuitive, it makes for a good starting point. In addition, you cannot change the characteristics of a room with an EQ, you can only change the characteristics of the signal coming out of the speaker. This can indeed change how a certain speaker may interact with the space, but you are not changing the room characteristics, only the signal. Gotta get clear on that.

On a side note, if you know the speaker’s general specifications, you’ll know what to expect. For instance, I happen to like a couple certain 15-inch two-ways because they are predictable. I know I will grab the EQ and notch out a little 1.25kHz every time. I like a couple ribbon tweeter devices because I know what they will do before I hear them. A lot of touring guys will talk about speaker characteristics like they were people with personalities. Rarely are a speaker component and “the space” a perfect match. Some compromises are almost always made. Good planning simply lets you make less of them. There’s no substitute for this kind of knowledge except lots and lots of listening.

“Could a good feedback eliminator replace the standard one-third-octave EQ?”

Answer:

In my humble opinion, feedback eliminators are for those who have been led so far down the dark path of misinformation that there are no alternatives left. In the last 100 systems I’ve installed, I’ve not used one, and I never will. I’ve never sold one in 25 years.

If the right speakers are placed in the right position, the gain structure is solid, good quality mics are used correctly, stage monitors are kept to a minimum, personal monitors are utilized and the system is tuned well, you should never, ever need a feedback eliminator. That’s my story and I’m sticking to it.

The typical problem we encounter in Houses of Worship is low-quality lavaliere mics, poorly placed on pastors who like to wander around. I love when preachers are animated, and when they have good lavaliere mics that have substantial gain before feedback. Spending money on the right lavaliere can not only eliminate feedback but can also give better overall sound quality. If you really just have to beef up the pastor’s lav, get a good quality one-third-octave graphic (or parametric) and maybe a simple “sweetener” like an Aphex 204 and bounce out of the inserts on just that sub-group or channel. Don’t overdo it.

But to make a long answer short: no, a feedback eliminator cannot replace the FOH one-third-octave EQ.