Tech: Setting up your EQ....

Subject: Tech: Setting up your EQ....
From: Clinton Hammond
Date: 17 Jun 03 - 07:51 PM

.. especially on your PA...

I know... a lot of people just wimp out and rather than actually learning how to use the thing, they just take the salesmans advice and "make the smile" out of the sliders on the EQ... Which is just wrong, and we know it...

So how does one find out how to set it up properly?

Subject: RE: Tech: Setting up your EQ....
From: NicoleC
Date: 17 Jun 03 - 08:43 PM

Unless you are trying to ring out a live room, EQ is highly subjective. If it's your home system, do what you like. A good way to start is to play something you are intimately familiar with that you've already heard on a great system, and tweak to that. The "smile" works for many people because it boosts the higher and lower frequencies that most people can't hear as well. However, many, but not all, albums compensate for this in the first place.

Graphic EQ's in cars largely take up dashboard space without providing much improvement over bass & treble knobs, because the subtlties of EQ will vary with road surface, weather, etc. etc.

If you are trying to EQ a room for live performances... well that's a lot more complicated. You SHOULD:

- Rent a pink noise generator.
- Rent a spectrum analyzer.
- Have an EQ channel for each set of speakers.
- Make a lot of pink noise through each set of speakers individually, and using the spectrum analyzer, flatten the room.
- After doing each set, do them all together and tweak them.
- Put away the pink noise generator
- Ring out the mics by turning up the gain past where it would normally be and walk around talking into them. The spectrum analyzer will help if you aren't good at picking the frequency that's ringing.
- A perfect flat EQ is safe, but boring. Insert very familiar CD. Play loud. Tweak as needed to create the audio characteristics of the room you desire.

However, this can all take several hours and is a lot of work for a one night gig even if the place will let you do it, which is unlikely. If you can do it once for your PA in a typical room that you would perform in, you have a baseline of what will probably sound good with your system, to help compensate for inherent weaknesses, etc. If possible, hire or beg help from someone who has done this before: it's not just science, it's art. Pay attention and ask questions though -- you will learn more about your PA setup than a spec sheet will ever tell you. Write ALL the settings down when you are happy. (Legibly!)

Then, for your typical bar performance, set up your baseline, skip to ringing out the mics and tweaking to your chosen CD (and I suggest using the same song over and over when you have picked out one that works well for you), then go on to sound check. Keep a log of your EQ settings and note how well they worked out -- eventually you will probably start modifying your baseline starting point for what usually works.

By keeping a log, when you return to the same venue, you have a better place to start from, and you also learn the stuff to avoid in general. Even if you don't ever get the chance to really pink your system, a log will go a long way toward helping you make improvements to your setup.

Subject: RE: Tech: Setting up your EQ....
From: reggie miles
Date: 17 Jun 03 - 08:46 PM

I hope you get an answer to this one Clinton cuz I'd like to know as well. That "smile" setting thing is all I've ever heard about and had folks (other entertainers too) swear that the "smile" was the way it should be done. Being a suspicious sort, I too, deep down, have always suspected that that answer was just too simple and easy to be the true or correct way and have longed for the day when I could flaunt superior knowledge and sound better via all these goofy knobs and sliders.

Knobs at the ready and waiting.

Subject: RE: Tech: Setting up your EQ....
From: NicoleC
Date: 17 Jun 03 - 08:56 PM

Er... clarification. I was referring to systems with graphic EQs. If you just have individual channel parametic EQs, the pink noise will be a waste of time, but ringing out the mics and logging everything will be more important.

How to set up individual channel EQs BESIDES cutting feedback is a lesson for another day... just as soon as I figure out how to put it into words.

Subject: RE: Tech: Setting up your EQ....
From: Amos
Date: 17 Jun 03 - 09:02 PM

Nicole:

What is "pink" noise?

A

Subject: RE: Tech: Setting up your EQ....
From: reggie miles
Date: 17 Jun 03 - 10:16 PM

Hey Carol, I've got an old stereo component by AudioControl with a real time spectrum analyzer and pink noise generator but I'm not one of those boys that makes a whole lot o' noise when he plays. Can this still work to my advantage? I hooked it between my Phase Linear 400 and my Samson mixer and it picks up the signal and allows me to play with it n the EQ the pink noise input is separate and has a mic jack input next to it. I'm not sure what two lines to connect to it, the ones from my mixer I'm guessing. Is that correct? I got it a garge sale and it came with no instructions. Does the pink noise get pumped to the mic as the noise is fed via the speakers? Then the analyzer detects the proper balance or do I set the balance near flat or as it sounds good to me???

Subject: RE: Tech: Setting up your EQ....
From: NicoleC
Date: 17 Jun 03 - 10:22 PM

Short answer: A godawful racket where all frequencies are represented equally. The goal is to get the exact same racket reaching your ears.

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Long answer: Pink noise is audio signal with equal power per 1/3 octave. (White noise has equal energy per *frequency.*) So when you "pink" a room, you are sending every frequency through the speakers at the same level. (It isn't, really, but that's close enough for now.)

In reality, the system a) probably will not be able to produce it exactly that way and b) the room has audio characteristics of its own that alter the sound after it comes out of the system. By changing the EQ you are sending through the speakers, you seeking to reproduce that flat pink noise level.

Why? Well, every room is different (and slightly different on every day based on numerous factors), so you never know what you are going to get. For example, let's say you are in a room with hollow walls. This is common in older buildings where a performance space has been retrofitted by building out the walls and running cabling behind them, etc. The floor might also have been built up for a rake, so the audience may be sitting above a hollow floor as well. Chances are, the room is going to have a real problem with something around 300Hz. You're gonna have that frequency runing back and forth accross the room and getting in all your mics and it's gonna feedback something vicious. When you pink, you watch your spectrum analyzer and you find out that particular problem and pull it way down out of the EQ, so you are less likely to have problems while the performance is happening.

It won't be perfect, because different parts of the room will respond differently, but it will get you in the ballpark.

If you want to pink your system without the room, you can buy a pink noise CD and compensate for what your PA actually produces. It's a start; later you'll make changes for the room you're in. White noise can do in a pinch, but it's not the best choice for a live setup.

The latest studio design vogue is moving away from rooms with a flat frequency response in favor of character, but for a live setup, it's the most predictable and manageable. In live sound, predictable is oh so good, 'cause you don't get a second take!

For samples, go here and click on the different "noise components" to the left.

Subject: RE: Tech: Setting up your EQ....
From: Clinton Hammond
Date: 17 Jun 03 - 10:31 PM

Ug... maybe I'll just hire a sound tech...

Subject: RE: Tech: Setting up your EQ....
From: NicoleC
Date: 17 Jun 03 - 10:35 PM

I'm guessing Carol is supposed to me me...

>Can this still work to my advantage?

Yes. Your performanace volume doesn't matter. Your benefits will be a lot less than a group with 10 mics on stage, though. Pinking is primarily a problem prophylatic (see above post) and secondarily a way to make things sound better.

Diagram for where everything plugs in here. (Cool web page on sound concepts, BTW. Ah, the power of Google.)

Important note: DO NOT ALSO SEND THE MIC THROUGH THE SPEAKERS!!! The mic plugs into the spectrum analyzer!

>Then the analyzer detects the proper balance or do I set the balance near flat or as it sounds good to me???

The analyzer shows you what is actually being heard in the room, if you had perfect ears. (And if it's a good mic for the job. Most Spectrum analyzers come with anappropriate mic.) Use the analyzer to adjust the EQ to make the response flat. In theory, you will then be reproducing output equal to the input.

But it doesn't have to stay there, because flat response does not necessarily equal the best sound for you. When you put music through it, if you don't like the way it sounds, change it. Knowing what to change is harder, because you don't know which frequencies are which. Experimentation is the only way to learn, although I could discuss techniques to experiment until I'm blue in the face.

If you change a lot, occassionally turn the pink noise on again and be sure no frequency has bumped up too high, or it may create feedback problems later.

Subject: RE: Tech: Setting up your EQ....
From: reggie miles
Date: 17 Jun 03 - 10:41 PM

Oops, thread mix up, too many threads, thread overload, error, error. My sincere apology Nicole.

Subject: RE: Tech: Setting up your EQ....
From: NicoleC
Date: 17 Jun 03 - 10:46 PM

:D

Subject: RE: Tech: Setting up your EQ....
From: reggie miles
Date: 17 Jun 03 - 10:48 PM

Hmm, my AC octave equalizer has the spectrum analyzer and pink noise generator all in one unit so the setup at that link won't work for me.

Subject: RE: Tech: Setting up your EQ....
From: NicoleC
Date: 17 Jun 03 - 10:59 PM

S'okay. The PNG has an output for the pink noise, right? Plug that into the console -> amp -> speakers. You've done that part.

Then use the mic input jack and you should be done.

Subject: RE: Tech: Setting up your EQ....
From: reggie miles
Date: 17 Jun 03 - 11:19 PM

Thanx a million. I should be in the pink and soundin' gooood for the next gig.