“Master” Your Amp Sim

March 1, 2010

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. Let’s look at getting better sounds through post-sim EQ.

Fig1The pickup on this guitar has a peak at 1.39kHz. Cutting gain at that frequency improves the sound dramatically.





Fig2This EQ response takes out the midrange for a scooped sound.






Fig3In addition to cutting frequencies and rolling off the highs and lows, an upper midrange boost helps the guitar cut through a mix.




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 (such as 44.1kHz). Many EQs have a lowpass filter function that attenuates levels above a certain frequency. Set this for around 5kHz-10kHz, with as steep a rolloff as possible (12dB/octave is good, and 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.


Amp sims can do remarkably faithful amp emulations—warts and all—but the recording process often smoothes out those warts a bit, due to miking, mic position, sound traveling through air, etc. Another consideration: Different amps sound different with various pickups, strings, and so on. 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.

First, turn down your monitors because there may be some really loud levels as you search for the annoying frequency (or frequencies). Now, enable a parametric equalizer stage. Set a sharp Q (resonance), and boost the gain to at least 12dB. 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. Now, use the parametric gain control to cut gain, thus reducing the annoying frequency. Similarly, check for and reduce other annoying frequencies, if present.

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!

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