Digital Tape, Pt. 4: Getting Smooth Tones

tape

The analog vs. digital debate is a topic unto itself, and I don’t have any interest in engaging that; I use analog tools where appropriate, and digital tools for the same reason. However, a little backstory is appropriate. When you’re recording entirely in the analog domain, every action you take loses you some high frequencies. Run it through a desk? Lose some HF. Run it through a compressor? Lose some HF. Record to tape? Bounce to tape? Play the tape? Lose some HF. Along the way, we got used to the tone that came from all those analog passes. Then along came digital, promising superior fidelity with no signal loss. Bad converters aside, the consensus? It’s harsh! Cold! Brittle! Digital, with all its superior fidelity, often seems to be missing a little charm.

These days we have the best of both worlds; if you want the sound of tape, tubes or transformers, you can record through tape, tubes and transformers without having to worry about signal loss down the road. I didn’t grow up on vinyl, and I don’t have any nostalgia for low fidelity; however, there is something to the way analog gear handles high frequencies. I’m going to explore a couple of options for emulating that response with more precision.

essence

For tonal content, DMG Essence is an absolutely amazing tool. While it’s billed as a mastering de-esser, it’s really a sub-band processor that allows you to selectively compress specific frequencies. In practice; let’s say you’ve got a vocal track that sounds fine when the singer’s quiet, but sounds harsh when they hit the chorus. You can isolate the offending frequency and set the threshold so it only engages at high levels, effectively smoothing out the signal. This technique can be used with high ratios to deal with resonances in instruments or amps (even feedback), but if used subtly (with low ratios & gentle filter slopes) it can emulate the way tape attenuates high frequencies when pushed. With experimentation you can achieve this effect very transparently, without the inherent noise or distortion of tape.

deedger

OD DeEdger offers a similar feature set that’s tailored to transient content. While the controls are much simpler, the concept is the same; pick a frequency, pick a Q, and set your threshold. DeEdger is perfectly suited to taming grating percussion, crunchy amps, and the high-mid sharpness you can get from cheaper condensers.

There’s no denying that analog gear is a lot more fun to play with (and makes for a more impressive studio shot), but not owning a $7,000 preamp is no excuse for not having euphonic tone. Hope this series helped you get a little closer to that!


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Digital Tape, Pt. 3: Gain-Staging Drums

Note: the following post makes use of Klanghelm VUMT and TDR Limiter 6. To get the most out of these posts, head over to their sites and support some awesome developers!


drums

In our last post we covered how to apply analog gain-staging practices to melodic material. However, our ears respond much differently to percussive material, which is composed of transients instead of tones.

ppm

A PPM meter responds much more quickly to level changes, and as such it’s better suited to drums and percussion. Using VUMT, pull up a simple DIN meter and apply it to a snare or kick track. Adjust the pre-fader clip volume so that the needle is reading a little under 0.

Here’s an example of a snare track after I’ve adjusted the gain:

snare

You’ll notice that while the hits are fairly consistent, there are couple hits around the 1/3rd mark that are much louder than the rest. In our last post, we dealt with this problem by manually adjusting the volume; while this is a completely valid approach, it’s not always an option to go through hundreds of hits by hand. Instead, let’s take an analog approach.

Back in the days of tape, meters weren’t fast enough to respond to “peaks” as we think of them today; when your meters are sitting around 0PPM, loud hits like the ones above can easily slip through without being caught. However, tape responds much differently than a digital recorder. When audio reaches maximum level, tape goes into saturation, clipping peaks while generating harmonic distortion. While this effect is rarely desired for melodic material, for drums it not only preserves most of the dynamic impact, but can actually enhance the sound. In the digital domain, we can selectively use this effect to enhance our drums in a much more transparent way.

clipperTDR Limiter 6 ($60 USD) is an incredible plugin that’s perfectly suited to the task. We’re going to use just the clipper module here, set to a drive of 0dB, threshold of -6dB, knee of 4dB, and with the mode set to “open.” This gives what’s called a “soft clip” that’s very similar to the clipping properties of tape. If your peaks are sitting around 0PPM, the clipper shouldn’t be engaging regularly; at most, it should be shaving off 0.5 dB from your hits. But on those few errant peaks, the clipper will dig in and clip off the tops, just like tape. You shouldn’t be clipping more than 3dB unless you want audible distortion, and there are better tools for that job than a clipper. What we’re doing is emulating a property of tape to transparently control our peaks. While Limiter 6 is a great option, any plugin with a soft clipper should be able to accomplish the task.

Just as before, we don’t need to delve into the technical side of this to go on with our mix; by following the steps above, you’ll have drum hits that are dynamic and consistent in level with the rest of your tracks.

No matter what methods you use, I can’t stress enough how important it is to take the time to gain-stage your tracks correctly before you begin your mix. By properly preparing your audio, you set yourself up for a fast, intuitive mix session that puts the best of both worlds into practice.

As an addendum, there are a few other techniques I use to selectively emulate some of the best properties of tape. Read on…

>> Digital Tape, Pt. 4: Getting Smooth Tones


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Digital Tape, Pt. 2: Gain-Staging Vocals

Note: the following post makes use of Klanghelm VUMT, an incredible plugin that costs about $15 USD. To get the most out of these posts, head over to the site and support an awesome developer!


vocals

Hugh Robjohns begins his article on VU & PPM meters with the following quote:

These are both, strictly speaking, obsolete analogue metering formats! In short, the VU meter shows an averaged signal level and gives an impression of perceived loudness, while a PPM indicates something closer to the peak amplitude of the input signal. However, in our modern digital world, neither meter really performs adequately.

He has a point; if you’re mastering for broadcast, you want a digital meter that’s able to respond with pinpoint accuracy. However, I’d like to focus on part of that quote:

The VU meter … gives an impression of perceived loudness.

While digital meters do a great job of letting you know if your signal is clipping, they don’t correlate much with what you’re actually hearing. One of the reasons people love mixing outside the box is that analog meters move the way the music does. So let’s set up some analog meters.

meter

Klanghelm VUMT is my favorite meter plugin, and it has far more features than we’ll need today. For now, just bring it up as a simple VU meter and apply it to a vocal track. Adjust the track volume (pre-fader) in the DAW so that the meter is reading around 0VU for sustained vocal phrases.

After you’ve set your gain, you’ll notice that there are some big variations in level; some phrases will be close to clipping, while others will barely move the needle. We’re going to take another page from the analog book and do some level-riding. If you were mixing on an analog desk, this would mean keeping your finger on the fader and manually moving it up and down to compensate for level changes. In the digital world, we can use our DAW to adjust the gain. In my case, I’ll use REAPER to cut it up into clips and adjust their gain, but you could also do this with trim or pre-fader volume envelopes.

Here I’ve got a vocal track with a lot of dynamic range. It was a live recording, so on top of the musical dynamics the singer was changing his distance to the mic, creating a wide range of levels:

track_original

First I’ll cut the track into sections (verse, chorus) and balance the gain between them. Then I’ll go in with more of a fine-toothed comb, adjusting individual phrases and words:

track_adjusted

The goal isn’t to kill the dynamics of the track, and you should make sure to audition each gain change to make sure it sounds natural. Here are the two clips compared, with the original on top:

track_comparison

As you can see, the levels on the bottom clip are much more consistent, while still retaining plenty of dynamics; the meter should be reading 0VU more consistently as well.

Now, go through the same process with any other tracks that contain melodic material; in other words, anything but drums. Your lead vocal is your loudness reference, so use your ears while you’re matching levels; however, you can aim for 0VU for legato tones (vocals, lead guitar, bass, horns, and bowed instruments), while more percussive material (rythmic guitar strums, hard piano chords) will clock in closer to -7/-5VU. Again, use your DAW to ride the levels and even out big variations.

You’re welcome to dive into the technical aspects of all this, like how to convert VU to dBFS and how headroom applies to the digital domain. But regardless of that, if you follow the steps above then you’ll meet all the goals we set in the previous post; consistent levels, adequate headroom, and good signal-to-noise. Most importantly, when your faders are at unity your tracks will all sound equally loud. With this foundation, the mix process becomes much more intuitive.

I’ve used the term “digital tape” because this process emulates how you’d gain-stage if you were recording to an analog medium. However, in the next post we’ll be looking into actually emulating some properties of tape in the digital domain, and how to use PPM meters to gain-stage percussive content. Read on…

>> Digital Tape, Pt. 3: Gain-Staging Drums


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Digital Tape, Pt. 1: Analog Gain-Staging in a Digital World

gear

In my opinion, gain-staging is the most important step of the mix process. Properly preparing your audio sets the foundation for your mix; unfortunately, this step is often neglected or misunderstood. I’m starting a series of short articles on how to apply analog mixing practices to the digital domain, in the hopes of simplifying this fundamental process.

One of the biggest differences between analog and digital is the way the equipment responds to level. When recording through tape & tube equipment, there’s a sweet spot in the middle of the range where fidelity and signal-to-noise is optimized. Get the level too low and your signal gets lost in hiss; get the level too high and it’ll distort. 24-bit digital is an entirely different picture; get the level too low and it’s not much of a problem, as long as your peaks aren’t clipping. Compounding this problem is the fact that digital meters don’t do the best job of representing what we actually hear.

Because we’re not fighting for a smaller sweet spot, we tend to be more relaxed when it comes to gain-staging in the digital world. This is fine for recording, but it creates big problems when you enter the mix stage, because:

  • if your levels aren’t consistent, your faders won’t be representative of the actual mix.
  • if you have multiple tracks that are close to peaking, they’ll clip your master bus when combined.
  • saturation, distortion, and analog-emulation plugins are level-dependent just like analog gear.

What we want is tracks whose levels are consistent in relation to each other, high enough to optimize signal-to-noise, low enough to leave plenty of headroom on the master bus, and gain-staged for use with analog emulations. How do we do this? Read on…

>> Digital Tape, Pt. 2: Gain-Staging Vocals


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