Thursday, November 3, 2011

The Equalizer -- A Tracking Engineer's Friend or Foe?

I love EQ.  I've got lots of equalizers.  Active and passive, graphic and parametric, fixed and sweepable designs, reciprocal and non-reciprocal -- LOTS of EQs.  I LOVE EQ!

Having said that, equalizers are not generally part of my first plan of attack when tracking an instrument.  You see, I also like things to sound natural, not mangled and fake.

I prefer audio to sound good.

Decades ago equalizers were very simple, broad-stroke devices that would perhaps better be termed 'tone controls' rather than an EQ (at least in the sense that we know EQs today).  The practice at the time was for an engineer to choose the proper mic and its placement to best capture the instrument(s) being recorded, and then reach for EQ to broadly correct any overall balance issues.  Back then music was generally recorded with far fewer mics than we use today, usually mixed down to a single track (or mono disc cutter).  Mic selection and placement was key.

Today, we use so many mics (I often use thirteen on a 4-piece drumkit alone), usually dedicating a single track to each one, so when it comes time to mix there is much more frequency interaction and overlap between all these sources, and, therefore, a greater need for filter electronics to sort through it all.  So common is our use of even complex EQ's nowadays that for many folks, particularly young engineers, it has become a primary approach for getting one's tones, and I contend that this should not be the case if you want well presented, natural sounding audio.

I see young engineers all the time placing a mic on an instrument according to the way they've seen it done in pictures in recording industry magazines, and then patch in an eq to fix what they're hearing in the control room -- STOP!!  Don't do that!  If your first mic choice and placement doesn't get you at least 90% of the way to the sound you are hearing in your head, then go back and choose a better mic for the source, or use better placement of the mic you have out.

'Why,' you ask?  Because all audio signals have this little thing called 'phase.'  No, I'm not talking about 'polarity', where we can flip the signal 180-degrees if we want.  Phase refers to the actual timing of frequencies within a given 360-degree audio waveform.  All audio electronics that accept an input and produce an output have a measurable 'phase response' which represents how accurate the timing of an output waveform is relative to the one at the input.  If things are properly in phase it means that the timing of the waveform is unchanged from input to output.

Equalizers not only change the amplitude of a given range of processed frequencies, but actually alter the timing of those frequencies relative to the original input signal.  What does this mean?  In the most practical sense it means that what comes out of an EQ is an unnatural version of the signal that went in, frequency-related amplitude notwithstanding.  The effect of this phase manipulation cannot easily be undone.  If you boost a range of frequencies when tracking a signal only to discover later that you shouldn't have done so, introducing more filter electronics (or virtual filter electronics by way of your DAW's EQ plug-ins) to correct the mistake won't undo the phase distortion of the original processing.  It can tame the amplitude of those frequencies, yes, but the second pass through filters will further distort the signal from its original phase integrity.

And it doesn't take much phase distortion to make a signal sound unnatural.  Most EQ's available to us today have many bands, and each band is screwing with the phase integrity of the input signal.  Pass after pass of filter electronics on all of your tracks will quickly leave an undesirable sonic fingerprint on your entire mix that often makes it sound less professional, or at least, leaves it lacking the authority of tone you want the finished product to have.

So what to do?  Trust your ears.  Go out in the room and listen to the instrument(s) you're about to record.  Walk around and bend down, placing your head in a variety of places to see what perspective best captures the instrument the way you want it captured.  Then decide which mic will fit the bill best, and place it in the spot where your head was.  Go in the control room and listen.  Then go back out and make adjustments as needed.  Then, only when you have gone as far as you can with mic selection and placement, if you feel it absolutely necessary, dial in some minimal EQ to get you the rest of the way there.

Here's a hint:  If you find yourself cutting or boosting more than +/-3dB or so to get a good balance to your recorder, I suggest you still need to mess with the mic and the placement (or choose a better instrument to record!).  The less EQ you use, the more authoritative and natural your tracks will sound.  Period.

(And this goes for live engineers as well, by the way, though other factors such as monitoring and avoiding feedback to come into play as well.)

Happy Tones!