"Master" Your Amp Sim

Mastering isn't only about working with stereo mixes

by Craig Anderton

In recording, mastering polishes your stereo or surround mix, typically using EQ and dynamics processors, to optimize the sound quality. Similarly, recording engineers often add these processors to recorded amp sounds in the studio, creating a more “produced” sound. With amp sims, using EQ and dynamics after the sim itself can make a huge difference in the overall “sweetness”—so let’s look at getting better sounds through post-sim EQ.

EQ: MAKING THE CUT

Real amps don’t have a lot of energy above 5kHz because of the physics of cabinets and speakers, but amp sims don’t have physical limitations. Even if the sim is designed to reduce highs, you’ll often find high-frequency artifacts, particularly if you run the sim at lower sample rates (e.g., 44.1kHz).

Many EQs have a lowpass filter function that attenuates levels above a certain frequency. Set this for around 5-10kHz, with a steep rolloff a(specified in dB/octave; 12dB/octave is good, 24dB/octave is better). Vary the frequency until any high-frequency “buzziness” goes away.

Similarly, it’s a good idea to trim the very lowest bass frequencies. Physical cabinets—particularly open-back cabinets—have a limited low frequency response; besides, recording engineers often roll off the bass a bit to give a “tighter” sound. A quality parametric EQ will probably have a highpass filter function. As a guitar’s lowest string is just below 100Hz, set the frequency for a sharp low-frequency rolloff around 80Hz or so to minimize any “mud.”

REMOVE ANNOYING RESONANCES

Amp sims can do remarkably faithful amp emulations—warts and all. But the recording process sometimes “smoothes out” those warts a bit, due to miking, mic position, and other factors involved in the recording process.

Another consideration: Different amps sound different with various pickups, strings, etc. An amp sim that sounds great with one guitar might not sound right with another one.

As a result, I’ve found that certain guitar/amp sim combinations produce what I call “annoying frequencies”—resonances that add a fizzy, peaky, unpleasant sound. Fortunately, you can get rid of these pretty easily with a parametric equalizer. The following presents the basic; there's also a more detailed article called "How to Make Amp Sims Sound More Analog," with lots of audio examples, if you really want to get into the subject.

1.  Turn down your monitors because there may be some really loud levels as you search for the annoying frequency (or frequencies).

2.  Enable a parametric equalizer stage. Set a sharp Q (resonance), and boost the gain to at least 12dB.

3.  Sweep the parametric frequency as you play. There will likely be a frequency where the sound gets extremely loud and distorted—more so than any other frequencies. Zero in on this frequency.

4.  Now use the parametric gain control to cut gain, thus reducing the annoying frequency.

5.  Similarly, check for and reduce other annoying frequencies, if present.

PUTTING IT ALL TOGETHER
Here are three examples (Figs. 1-3) of these EQ techniques being applied to particular guitar sounds.

Fig. 1: The piezo pickup on this guitar has a peak at 1.39kHz; cutting gain at that frequency improves the sound dramatically. Also note the high and low frequency rolloffs, and another cut around 500Hz.

Fig. 2: This EQ response takes out the midrange for a “scooped” sound. It might not look like any signal could make it through this, but it actually sounds very smooth.

Fig. 3: In addition to cutting frequencies and rolling off the highs and lows, there’s an upper midrange boost so that the guitar cuts better through a mix.

When you’re done, between the high/low frequency trims and the midrange cuts, your amp sim should sound smoother, creamier, and more realistic. Now throw a little compression on the guitar for a hotter sound, and enjoy your new tone!

  Craig Anderton is Editor Emeritus of Harmony Central. He has played on, mixed, or produced over 20 major label releases (as well as mastered over a hundred tracks for various musicians), and written over a thousand articles for magazines like Guitar Player, Keyboard, Sound on Sound (UK), and Sound + Recording (Germany). He has also lectured on technology and the arts in 38 states, 10 countries, and three languages.