Monday, March 7, 2011

Home Recording Tip 3-4: Only drums and percussive instruments should come close to filling up the meters in ProTools or any DAW

Meters. Even back in the analog days knowing how to read them was a skill. The same is true today. Back then there was a process of apprenticeship where engineers would teach their assistants about such things. The how and why of why meters responded on various instruments would be explained, and engineers were taught what they were seeing. Today however, there is precious little of that. Musicians and wanna-be engineers buy various DAWs and jump right in, doing the best they can from what they learned on their own and from friends…and not always for the better.

The key is remembering that this is all about getting the best level from your mic preamp. It’s the first stage of amplification and most often where distortion originates. And the intent of this blog is to help you get the best performance from your mic preamp. Once that is set, everything else will work better. Be it compressors, eq, whatever.

Most meters in a DAW are a combination of peak and averaging meters. Some of you may not know what that means, so here’s a brief explanation: Peak meter only look at the peak of a signal. It only shows the highest point of voltage….nothing else. That’s a useful thing for percussive instruments, like drums, but not for other things like vocal, strings, keyboards, etc. For those instruments, an averaging meter is better. Such a meter is what it says…it displays the average level if a signal.

The old VU meters that you’ve seen on tape machines and analog consoles were almost always averaging meters. The peak information would never show and we engineers were trained to know that. We were taught that certain things like tambourines were not showing the true peaks which were occurring. So when we’d record them, -10dB was the proper level of a tambourine because their peaks were at least 10 dB above the meter response. Were we to allow the meters to hit 0 we knew it would end up with distortion in the recording, most of the time both at the mic preamp as well as the tape. However with other things like vocals and the like, 0 was correct. (I’m ignoring super-elevated tape levels…that’s a lesson beyond this conversation and not useful for digital recording.)

So when DAWs came out, a decision needed to be made about metering. The choice was correctly made to create meters which were a combination of peak and average metering. These digital meters are somewhat of a compromise between the two. They show peaks and average levels. So percussive instruments will show their peaks. No longer do you need to have tambourines at -10 for a proper level. A meter reading close to 0 is probably correct. (This is assuming your preamp has enough headroom) And the other non-percussive instruments should NOT go up to 0dB, anymore than you’d record a vocal all the way into the red.

So basically, things you hit, be it a drum, funky guitar parts…anything with strong transients, those things can fill up 70-80% or so of the DAW meter. Anything else, vocals, keys, power electric guitars, acoustic guitars, etc, should really stay around 60% of the meter. Now having said that the key thing is always USE YOUR EARS! Depending on the mic pre you have you may encounter distortion even at lower levels. Class A mic preamps, like vintage Neve mic preamps will distort earlier than other kinds. So be aware…there’s no need to push your mic preamps. Digital has plenty of headroom and no tape hiss problems, so there’s no need to ever fill up the meters.

4 comments:

  1. This assumes that the digital peak meter is rectified. Most are not. It assumes the UI has the resources to show you all the peaks. Most do not. DAW meters can not be trusted, so even more "headroom" should be given for fast transients like percussion. And I'm curious about your claim that class A amplifiers are MORE likely to distort. Please explain. Thanks.

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  2. Agree for sure about the UI with pretty much all DAWs.

    As for the Class A comment, that's largely from my own experience with the pair of 1073s that I own, vs API and other mic preamps which are AB.

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  3. The color of the 1073 is probably more about overall circuit design than amplifier Class, in my opinion. At least in theory, a true Class A amplifier circuit should have quicker slew rate. But if you push past the headroom - regardless the Class - you can distort it. :)

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  4. I've heard you want Pro Tools DAW inputs to remain around -18db to -10db to allow enough headroom.

    I've been trying to keep it all under "the yellow"

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