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Distortion and power-tube saturation voicing: using the "eq->dist->eq" sequence

Keen's explanation of distortion - Notice how much this FAQ emphasizes the importance of filtering -- that is, eq curves -- before and after clipping. Craig Anderton also places the strongest possible emphasis on this relationship, so every guitarist should *master* this relationship.

Guitarists should experiment with this setup, which is merely implied in Distortion 101. It's very powerful:
low-noise EQ --> distortion pedal --> EQ pedal

I found the DOD pedal to be a little quieter than the BOSS as far as self-noise when cutting a band. The BOSS hisses more when you cut a band than when the band is at unity. But really you should use a rack EQ here, because they have far less self-noise. Any self-noise gets boosted by distortion.

You can explore an entire sonic distortion space this way. The first eq shapes the voicing of the saturation -- it shapes which input frequencies dominate the clipping. EQ before distortion is entirely different than EQ after distortion. The Boss effects catalog also recommends trying this.

For most distortion pedals, I like to cut the bass *before* distortion and use a V equalization after distortion.

For a hyper-EQ, you can use an octave doubler effect to super-boost the highs, or like Neil Young, use an octave halver to super-boost the lows. All this is before some sort of saturation/overdrive/distortion, so affects the distortion voicing rather than the final equalization.

When you place an eq pedal before a clipping box and another eq after it, driving a loud tube amp, you can control the level and voicing of the clipped signal driving the tube amp. But even with the power of pre-eq, you only have a limited control over the voicing of the distortion pedal. No matter how I eq'd before and after the Boss Metal Zone, it retained a distinctive breakup character, perhaps due to the levels and R/C eq connection *between* the internal, individual clipping stages within the pedal.
One overdrive recipe is to blend some clean signal with a quieter distortion signal, to create a kind of compression. When the clean signal drops, the distorted signal still stays at its fixed volume level. This way, the natural clean attack of the note is preserved, while the sustain effect of distortion clipping stretches out the note after the attack.

To a degree, you can convert a distortion pedal to an overdrive pedal by setting up your gear as follows. Use a Boss LS-2 line switcher pedal. Put a cable straight across the B loop. Put a distortion box in the A loop. Mix the two so that the peak of the clean signal pops up above the distorted signal. Use the output of the line switcher to drive a tube amp into power-tube saturation.

If you want to design a standard fuzz-type pedal, a standard distortion-type pedal, and a standard overdrive-type pedal, use the following approaches as a reference:

o Fuzz: boost the bass and cut the midrange, before clipping.
o Distortion: use a flat eq before clipping, or cut the bass slightly.
o Overdrive: use a flat eq before clipping, or cut the bass slightly, and mix some clean signal with the distorted signal.

All 3 pedals should be set up in a rig so that they drive a tube power amp into some degree of saturation.

>>>Eliminating muddy lows in my distortion design (06 Oct 96 17:24:20)

> I just finished developing a distortion box but I find that the lows come out a little "muddy"....any suggestions?

>>The typical distortion box design has a problem in that the presence of
>>bass notes in the signal tends to reduce the gain for the high notes.
>>This is why you get that muddy sound: the highs get swamped out by bass.

>>Some designs attempt to correct for this effect by splitting the
>>frequency range into separate bands, distorting them individually, and
>>then recombining these together at the output to form the total signal.
>>One example of this is C.A.'s Quadrafuzz circuit.

>I remember hearing Anderton's unit on a demo platter some years back
>and didn't care for it....

>Now what DID sound great was a friend's old 50W Marshall head. He
>cloned the first two tube stages in a separate box as a preamp. Tone
>controls on the preamp were set for min bass, max treble. Amp tone
>controls were set the opposite way. He added a gain control (really
>just an attenuator) at the output of the preamp. Varying the
>overdrive allowed control of the distortion. This sound excellent
>for both humbuckers and single-coil pickups.

That sounds familiar: use a ramp-up eq curve before a saturation stage, and a ramp-down eq curve after it. First this develops a fluid, glassy, treble-driven distortion, and then a smoothed treble and powerful bass amplification of that glassy distortion.

I'm not sure if you mean that your friend chained distortion stages, using the first for treble clipping and the second for bass clipping.

>A quick fix for your circuit might be to cut the lows between each gain
>stage by using a much lower value coupling capacitor. i.e. replace 0.1uF
>caps with 0.01uF caps. This clears up articulation somewhat by
>lessening the low notes' gain reduction effect on the high notes. You
>could then add a little bass-boost after the distortion to compensate.

>What would be really nice to have would be frequency independant
>distortion. Perhaps some brilliant transfer function exists that can be
>implemented using DSP techniques? Anyone...

Amps! The Other Half of Rock and Roll. Ritchie Fliegler. 24.95. 120 pages. Overview of tube amps: Fender, Vox, Ampeg, Marshall, Mesa-Boogie, Soldano, Gibson, Matchless, Hiwatt, transistor amps. Few schematics. British high gain approach (EQ after several stages of preamp gain ), vs. American early Mesa-Boogie approach (EQ early on in the preamp, before the distortion). -- The early Mesa-Boogie approach enables you to control the distortion voicing -- hopefully it has another bank of tone controls for controlling the voicing between the distortion and power-tube stages. Finally, for completeness, you need to control which speaker and cabinet and mic you use, along with electronic post-amp equalization such as tone controls for that channel of the mixing board. The pre-distortion tone controls on the amp would be essentially redundant with choosing a pickup with a certain equalization curve; both these means of equalization occur before the distortion stage. Going into even more detail: do these early Boogies place the first equalization bank before *all* gain stages? If not, then you could put in an eq pedal before the amp for yet another stage of eq-before-distortion-stage.

>I was thinking about purchasing a dual channel EQ for placement before channel 1 of the compressor, and after channel 2 of the compressor (beginning and end of chain).

One thing to watch out for -- squealing due to channel leakage feedback. If you run through the left channel of an EQ, then through a heavy distortion stage, then through the right EQ channel, you will get squealing, because the highly boosted/magnified signal in the right channel will feed back (through leakage inside the EQ unit) back to the left channel. So if you are doing any significant amplification in between the left and right channel, you have to use two completely separate EQ units, to avoid that squealing feedback.

>I can get an Aphex 107 parametric eq for a good price. Is a parametric the right choice for this application?

Parametric is excellent and so is graphic. I ended up wanting both; they both have advantages.

Be sure to run your signal high as possible without distortion, through the EQ, to avoid hiss - especially for the eq before any compression/distortion boosting.

You can run multiple distortion boxes in series, for a really ratty tone. That's what Sonic Youth did for the track "Mote" on the album Goo.

Guitar Player Oct 1992 cover story: Distortion. Page 40: The Grunge & The Glory: A Celebration of Distortion. Distortion/Tone Tips from the Loud & Mighty. Decoding Distortion: What It Is and How It Works -- includes the Quick and Dirty Distortion Primer, page 60, is an excellent article comparing how to assemble and set up a rig for getting shred tone vs. blues tone - my favorite article! This article is reproduced in one of the special issues; see my Books page for "Guitar Gear" issue. Fuzz Tone User's Guide: 31 distortion pedals. Rats in the Cellar: gallery of classic grunge - Art Thompson. Dialing for Distortion: sound advice from producers. Chris Gill.

Boss's litle stompbox booklet gives away one of my main tone techniques: Eq then Distortion then Eq, on page 41. They even have an odd idea, putting the regular EQ pedal in series with the Bass EQ (which has *some* different center-frequencies). Also, page 27 shows eq then overdrive, and overdrive then another overdrive. Note that I disagree about optimal FX placement; I recommend:

saturated power tubes and speaker, and eq

The Digitech 2101 processor did not have wah before distortion, or eq before distortion, or phaser before distortion, so I used another multifx processor to force this better placement. So much for the marketing literature's claim that "effects can be placed in any order".

The Boss booklet describes the 14 overdrive/distortion pedals offered by Boss, with a chart on page 23 - recommended reading. The chart would make a lot more sense if you have all the distortion pedals lined up in front of you for A/B testing.

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