Pre Distortion EQ
Equalizers are a tool used to shape specific tone frequencies and most often has been used in the
recording studio. Typical studio use includes cutting trouble some frequencies that tend to cause feedback
or boosting frequencies to heighten pleasant tones.
For guitarist EQ's have been used to boost volume for solos or help shape the overall sound of the
amp. Typically this involves placing the EQ after the distortion device whether thats a stomp box or
in the effects loop after the pre amp section of the amplifier. What this article will focus on is
placing the EQ before the distortion within the signal chain.
As mentioned in the first article we are using MXR 10-band EQs in our Rockman setups in order to
"de-Bostonize" our Rockmans in order to get a more versitile sound. This is done by cutting the
500Hz band which is key to the Rockman sound. Another example is the reverse, how to get the
Boston sound from a Marshall as Tom Scholz did for the original Boston album.
Scholz used an old MXR 6-band EQ pre distortion to get the sound he wanted. This was achieved by
boosting the 400 and 3.2K freqs while peaking the 800 band. A slight boost on 100, 200 and 1.6K
bands round out the Boston settings.
EQ Frown Curve
The Frown curve can be implemented regardless of which EQ your using. The basic frown curve is
a boost in the middle bands with a cut on the tails. How much or how little the cut/boost is depends
on personal preference. By focusing the boost or peak around the 700 - 900 bands this will smooth out
the distortion sound. Think more like Santana versus Metallica.
Though experimentation I found that the key is to keep the boost from sounding to mid-rangey and that
very subtle changes on the EQ can yield big results. Also, setting the EQ section on the amp to flat
when setting the pre distortion EQ is also helpful and using the amp EQ section to fine tune the guitar
tone was very benefitial.
Some Internet research turned up how using pre distortion frown curve can be useful in achieving a
EVH type tone with the following signal chain:
Double-coil bridge pickup -> EQ with frown curve -> Phaser -> Preamp distortion
EQ Smile Curve
Want the opposite of a Santana sound? Then maybe a smile curve is more appropriate. With the smile curve
we are cutting the middle bands and boosting the tails. Want a quick way to get a preview of this sound,
crank the bass and treble to 10 and dial the mid-range full to the left. The smile curve gets this type
of crunchy distortion sound by with more effect. While this sounds great alone it won't cut through
bass or drums so some mid-range is necessary.
By using the smile curve to get the crunch you want you can use the amplifier EQ to dial in enough
mid-range to allow the guitar fill in the mix.
Quick summary of pre distortion EQ:
- "de-Bostonize" a Rockman - cut 500
- "Bostonize" a Marshall - boost 400, 800 and 3.2k, peak at 800
- Frown Curve - smooth singing distortion ala Sanata
- Smile Curve - Crunch type distortion ala Metallica
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Feedback on Pre Distortion EQ Article
2004 11 28-JOEY
EXACTLY. EQ IS THE BEST EFFECT THERE IS, AND SO MANY PEOPLE DO IT WORNG. I USUALLY USE THE TONE KNOB/VOLUME/EQ PEDAL FIRST AND USE THE AMP EQ TO FINE TUNE, IF AT ALL.