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Audio Digital Signal Processing:
Not The Plugin Zone

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Of all audio mastering topics, digital signal processing is probably the most popular one.

  • Should I add compression to every track?
  • What’s the right EQ setting?
  • How do I do mid-side?

This along with “who” makes the best “what”!

What This Page Is About

So let me be clear here:

  • This is not a review.
  • This is not about the plug in zone.
  • This is not about mastering plugins.

This is about what they do.

It’s an overview of the processes I use to deliver professional audio masters for the people I work with.

Matters Of Interest

Here's the topics I'll touch on:

The Simplest

One of the simplest signal processes is volume adjustment – or leveling – or gain riding.

Yes sometimes the best solution is the simplest.

It’s important for me, as a mastering engineer, to know the order of songs when I master an album project.

Volume Contro


A song may stand fine on its own, but sometimes the opening may come in too strong or too weak, based on the previous song’s ending.

For example: If a song seems to start abruptly after the fadeout of the previous one, simply starting the song just one dB lower and then slowly easing in to its original volume can be just the right magic tweak needed to make everything sit just right.

Since it’s been noted the most humans begin noticing a level difference when there is a 3 db change, I keep those kinds of changes, well under that amount.

However, my ears are always the final judge.


Compression automates those level change processes – but in quite a different way than I just described.

With the just the right settings applied I can:

  • warm up a track,
  • add punch,
  • or smooth things out.

Extreme Measures

Limiting is a more extreme form of compression.

In mastering, I will almost always use a digital brickwall limiter. With this I can:

  • prevent digital overs to stop clipping and distortion on playback;
  • make a track louder.

Here is where a LOT of consideration is needed:

  • Make your track too loud and you’re ultimately going to tire your listeners out

Think very carefully if you really want to be a part of the loudness wars.

Containment and Confinement

Sometimes, ‘volume changes’ need to be confined to certain frequencies in a track. This is where filters come in.

Assemble a bank of filters and you have:

An Equalizer.

Filters can be arrayed in series; or in parallel (like the Manley Massive Passive or Steinberg’s graphic EQ’s).

My goal when applying equalization in a mastering project is to preserves the artist's original intentions, while making the song more pleasing to listen to – repeatedly or for long periods of time.

In other words: my goal is to keep the your listener engaged and wanting to come back.

Impossible Impressions

Analog emulations are another method of audio digital signal processing that attempt to make a track more pleasing.

The main ones involve emulating:

  • tape saturation (UAD-2 Ampex 102; Waves Kramer, Cube-Tec Magneto)
  • tube warmth (Wave Arts Tubesaturator; Ozone 5 Triode)

There are also more specialized audio enhancement processes, for example, that can:

  • bring out the higher frequencies in a more dynamic way (SPL Vitalizer)
  • 'deepen' the bass region (Waves Renaissance Bass: Dave Derr’s Fatso Tranny Control)

This, of course, would be done in ways that would be difficult or impossible to achieve with the more standard procedures like compression or EQ.

They are also considered more exotic forms of digital signal processing. Definitely not the first process on the list!

Leveling The Field

One of my specialties - mid-side techniques - deal with the imaging aspects the stereo field.

If I use this process, I can:

  • widen;
  • narrow;
  • correct

… the stereo image.

This correction is different from what a simple left/right volume change would accomplish.

Like enhancement processes, mid-side procedures are more exotic forms of digital signal processing.

It’s something I will apply with great care - and ONLY if needed.


These processes can be combined to create new sounds and color shadings.

For example:

  • Tubesaturator not only offers pleasing tube distortion but a mastering EQ as well.
  • UAD’s Fairchild has tube coloration in addition to its compression circuits.

Many programs now include mid-side options with their audio processes. More examples:

  • PSP Neon linear phase equalizer.
  • The UAD Fairchild (again) has the option for mid-side compression

When mid-side techniques are combined with any of the above procedures, the power of audio digital signal processing is raised to a whole new level!

So What Digital Signal Processing Do I Use Most?

That, as always, will depend on the individual song and the project.

The most important process is:


Many times. To hear what - if anything – is needed.

I, first and foremost, listen for, and respect, the artist's original intentions.

Drastic changes are NOT the rule. Unless I’m told otherwise. Or if I feel they are absolutely needed.


  • such drastic changes never happen without consulting first.

Mastering your own music can be extremely challenging.

The most crucial downfall of this approach is the complete lack of any objective viewpoint, after you’ve spent months - maybe years - on a project.

Leave It To Me

As a leading advocate for going with one’s strengths, I have this suggestion:

If after trying things out yourself, you’re more in the dark than ever, it’s time to let go and look outside yourself.

You Can Recover Valuable Time

Yes! Valuable time you can better use to promote your music!

I offer professional, affordable audio mastering services.

  • It’s my passion!
  • It’s MY strength!

Digital signal processing - wherever and whenever needed - at its finest.

Give me a shout!

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