No Excuse For Distorted Recordings

Posted: June 30, 2010 in Uncategorized

I’ve said it before and I’ll say it again……in the age of 24bit (or higher resolution) there is NO excuse for distorted recordings.

I can’t count how many demos I get where multiple elements, or God forbid, the mix bus is distorting.  Or when I’m watching interns/students/young engineers work and I see more red lights than not in Pro Tools.

Let’s start with some simple audio math than any engineer (budding or otherwise) should know.

1bit = 6dB

So, a compact disc or other deliverable are typically going to have a FINAL resolution of 96dB.  Now, for normal pop or rock music that is ample headroom as it stands.  Especially considering your average pop/rock recording has a dynamic range of about 3db……..sad (but that’s another topic)

Now, when we are recording, we usually start out with a bit rate of 24.  This resolution is 144dB.
This is 48dB MORE than our final destination medium!  48dB!
Your most dynamic pop song you can find me probably doesn’t even have a 48dB dynamic range total.  But that’s in addition to the original 96dB.  That’s a hell of a lot of headroom.

(As a side note, people always ask me if they should record at 32 bit floating point.  I always tell them, don’t bother with 32bit.  24bit is more than enough for what MOST people are doing, and it’s compatible on all platforms.  If you ever need to deliver 32 bit files to a Mac user, you’re going to be out of luck…..but that’s just my opinion.)

144db of dynamic range is more than enough to work with.  It’s definitely more than a CD’s resolution, and obviously higher than analog tape.  So why are we clipping our recordings?

I think there are 2 main issues at hand.  These are:
1.) improper gain staging
2.) deceiving metering on digital systems and more specifically…plugins

Improper gain staging

There are multiple factors at play here.  Recording too hot and mixing too hot are the biggest culprits.  Again with 24 bit, the noise floor is so low that there is no reason to record hot.  Clipping your A/D converters is the LAST thing you want to do….never a pleasant sound.  Mixing too hot becomes a little more complicated to control.  In the analog domain you typically have two things going for you to help prevent this.  The first is better metering throughout the chain, and the second is no SCREEN to look at…..forcing your to use your EARS *gasp*!  In the digital domain however gain staging seems to be a lost art.  Young engineers seem much more eager to turn those lights red, like it’s a game.  “Hey I managed to get my signal so hot that it lights up!  I get a prize!”  Sadly, mixing in the box does feel more like a game.  It seems less serious, less like you’re actually working.  These psychological factors, I truly believe, have a tremendous impact on how we mix.  It also seems like a race to put as many plugins as you possibly can on one channel.  This complicates proper gain staging even more.

Many times I’m guilty of the nefarious action of mixing in solo first.  I pull up the kick and snare, eq, move on to the rest of the kit and then start pulling up instruments in succession.  This is a horrible way to mix, but for some odd reason I know that, and I continue to do it. If you read an article with any of your favorite engineers that have many more grammys than me or you, they usually always pull up the entire mix and work on elements while everything else is playing…..never solo mode.  This also helps to keep all of your levels in check as a collective.  If you start working on the kick and getting it nice and loud and punchy, then you add things element by element, the entire mix will keep getting louder and louder, until finally you realize by the time you got a nice loud mix going that you’ve got 2 dB left until the master clips.  Or by the time you’ve reached the last instrument, that fader sitting at the top of its throw and still isn’t loud enough.  So then you have to pull the whole mix back which isn’t a fun thing to do.

Or in the case of most younger engineers I see, they DON’T pull it back.  They leave it at the top of the scale and throw a limiter on top if they need more loudness.  Not a good way to start a mix.

DECEIVING METERING in digital systems

Let’s start by taking a look at this guy…

Where is zero?  It’s TOWARDS the top, but it’s not at the top.  What else do you notice about it?  Zero is red, and everything above it is red.  Red usually means bad right?  Well, we can assume that we probably want to stay away from that red zone for the most part.  Obviously, as engineers, we know that we have a decent amount of wiggle room above zero and that some of us even live above zero.  But, we know that for optimal operation, we should stay around or below zero.

Most of the analog guys already know that in most studios, we usually calibrate our digital systems so that our ANALOG zero (console/preamp/etc) is equivalent to -18dB on our digital system.  We’ve got 18dB above “zero” on a digital scale before we clip the digital mix bus.

The problem is, that’s not how digital meters in our DAW reads.  It looks like THIS…

Now zero is at the top.  Red is at the top.  We can keep going right?  There is so much green to work with!!!!
We shouldn’t be treating this meter any differently, although most people do because the scaling is different.  Not to mention, the area that we should be working in is a very small section of the meter because of its logarithmic nature.
Dorrough recently released a plugin version of their meter, which is MUCH better suited to the way we should be working in digital as well as analog.

The individual channel meter and mix bus meter are just the tip of the iceberg.  The real problem lies with plugins.  We’re not usually going to be mixing without plugins.  Most of the time we’ll be EQing or compressing SOMETHING, right?  Well, tell me, how do I know what’s going on with THIS meter?

It’s not easy to see.  Especially when you start piling on the plugins.  Gain staging becomes more and more difficult.  Granted we should always be LISTENING to what’s going on, but that’s not really what this post is about.  This post is discussing those who DON’T listen….those who mix with their eyes.

There are many other factors at hand, but in my opinion, these two are the most pressing. None of this is new.  In fact Bob Katz discusses all of these things quite extensively in his book.  Mastering Audio – The Art and the Science.  It’s a very informative read and I definitely suggest it to ANY engineer. Hopefully through education and a more analog way of describing audio, we can help people realize that a digital system has its own set of rules and needs to be treated accordingly.  But most importantly, use your ears!

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