|1. Foreword||2.About music||3. About rock||4. About sound||5. About mixing||6. About guitarists||7. About tubes||8. About pedals|
|9. About digital||10. Ab. compression||11. About saturation||12. About filters||13. About delays||14. About chorus||15. About switching||16. Synthesis|
An overdriven solid-state circuit (transistors, FET’s, OpAmps, etc…) can give similar results, and can be used to obtain the same sound as a tube amp – provided you can control the result with the proper filters.
Clipping can also be obtained without active saturation: you can use diods to achieve clipping, because their natural behavior is to clip one half of the signal. Diods are actually in-between components based on the same technology as transistors, but they are used as passive components.
That’s a brief recall about saturation and its objective: clipping. We want to clip the signal to obtain a sound that has some musical qualities.
Oh, I was forgetting something critical about saturation and clipping: they don’t only alter the dynamics of the original signal. They just suppress it! In other terms, a saturated signal has the same dynamics than a hyper-compressed signal – though the principle is totally different.
So what? Losing the dynamics makes a guitar sound absolutely different, as if it was another instrument. And that’s what makes it attractive for rock music: this new instrument – saturated guitar – has its own identity, its own culture, and even allowed creating new styles of music: hard rock, metal rock, heavy metal, arena rock, wouldn’t exist without saturation, or should we say, clipping.
So, what does clipping, exactly? Clipping does two things:
Great, but we already had natural harmonics, hadn’t we? Yes, we had, and they are still here. So a saturated guitar signal is made both of natural harmonics and artificial harmonics… Merging the two families (artificial and natural) of harmonics (they all have the same frequencies) will cause complex inter-modulation effects. Some interactions are pleasant to the ear, and some are not. Moreover, the possible number of combinations is simply huge – and this explains why there are so many types of saturations, distortions, fuzzboxes, overdrives, etc…
All these effects are based on the same structure. All. They just differ by the filters placed before the clipping stage, that control the input signal harmonics distribution, and the filters placed after the clipping stage, that control the result – natural and artificial harmonics. You can of course, make things more complex by placing several clipping stages in the circuit, but the final result will not really change.
As for the clipping technique, each manufacturer has his favorite approach: FET’s, OpAmps, regular diods, tubes, bipolar transistors, MOS-FET, etc…Tom Scholz has selected the LED clipping technique, probably after a long series of tests and prototypes, and, why not, because LED’s light up when they clip!
“I don’t use tubes or transistors as overdrive elements; I use LED’s […] It doesn’t matter if it’s tubes, transistors or LED’s, if you do the right thing with them. On Third Stage, for instance, I started off using tube amps for several of the songs. I went back later and changed some of the parts so that some songs had pieces of tubes and Rockman. Nobody can tell which is which: I can only tell you because I was here (Guitar World, Feb. 90).”
The clipping element is a basis, the component that will create these artificial harmonics. As a standalone circuit, a clipping diod, transistor or tube sounds horrible. The art of distortion doesn’t stand in the choice of this clipping basis: it stands in what you connect before and after it to get something musical.
And what you place before and after are filters.
Copyright Rockman.fr 2007