Distortion - It's about EQ (low level self reinforcing rant)

[WGTP]

As the forum elders have told us previously.

I don't think EQ gets enough respect around here, me included.  Lets look at the Fuzz Face.  How many places are there to adjust the EQ. 

There is the input cap, the by-pass cap and the output cap.  Thats 3 places (pre, during and post distortion) to tweak the EQ and they will each have a slightly different effect because of there location in relation to the generation of harmonics (distortion).  Those are mostly changing the low frequency roll off frequencies and roll of rates.  By "cascading" the 3 you can get 1st, 2nd or 3rd order filters, sort of.  Rolling off bass makes the treble balance louder.  If you make a cap large enough, you are in effect removing it from the mix of bass roll off.

If you add a resistor at input to increase/adjust impedance (a common mod), that is 4.  There are 3 or more places to add caps for high frequency roll off and and again cascading...  A couple of mods that parallel caps with existing resistors  appear to boost or cut bass/mids or mids/treble to varying degrees.

Almost forgot, depending on the transistors used, and their various parametiers, bass/treble EQ is effected, as well.

The point is, you can get a lot of variation out of a simple circuit by just varying the cap/resistor values.  The impedance in the area effects the roll off value of the cap, so changing resistors in the area will effect the EQ, as well as caps.

When you start looking at distortion circuits as they evolved, you have the same situations with resistors and caps.  Distortion +, Tube Screamer, Tube Sounding Fuzz, BMP, etc.  Some contend that the Jfet emulations sound similar to the originals due to the EQ, rather than the "tube like" distortion generated by the Jfets.

Sure, you can place a 10 band EQ before and after the distortion for maximum versatilty, but that doesn't seem to be overwhelming popular, at least I don't see lots of discussion of that.

This leads me to notch filters and the infamous Big Muff Pie Tone control.  Simply changing one component value creates a different sound, a different tone, a different distortion pedal.  If you haven't figured out how to use the Duncan Amp Tone Stack Calculator, you need to and if you don't understand harmonics and filters, you need to and if you don't understand it all better than I do, you need to.  Thanks for you patience while I got this out of my system.   

Discuss...

http://www.duncanamps.com/tsc/index.html

[R.G.]

Ah, it's good that you begin to see, Grasshopper. 

[Mark Hammer]

It's all about 2 questions actually:

1) Harmonics of what?
2) How much of which harmonics?

That's pretty much it.  I'm serious.  Everything else is about how long the harmonic activity lasts, so Q#1 and Q#2 across time.

[captntasty]

Oh yeah!  The FF is one of the most simple but ingenious (whether by coincidence or design?) circuits out there that lends itself to such an astounding variety of modification it boggles the mind.  Me thinks I could build FF after FF and never get bored varying component values and adding variable pots and switches to create new tones.  Also, getting to know the circuit on a basis of how the signal is actually being electronically manipulated is a virtual electronics classroom.  Let us all sing the praises of the venerable FF.