I have a question about guitar distortion pedals?

guitar volume pedal image

the_dude

Many players (including myself) prefer the sound of distorted tube amp circuitry vs. transistor circuitry. I know the distortion is produced from the overdriven tubes, whether preamp or power amp, and adjusting the guitars volume as well as the amps volume (channel and master) will effect the distortion as well.

All this said, why then, do so many of us use distortion pedals? What exactly is the pedal doing? Is it increasing the gain of the guitar signal to overdrive the tubes, or is it processing a synthetic "distortion" tone?

Example: If a guitarist with a Marshall JCM 800 plays his guitar through its clean channel and steps on his distortion pedal, (lets say it’s a Boss OS-2) is he getting tube distortion (is the pedal now overdriving the tube by increasing the gain) or is he actually getting transistor distortion introduced into the signal via the pedals transistor circuitry?

Anyone? I'm interested in the basis for your answer as well. Thanks!
Thanks for the responses, but perhaps I should clarify the question- I'm wondering if using a distortion "effect" of any type- actually overdrives the tubes in a tube amp to produce the "distortion" or if it introduces a "processed signal" into the chain.

I am completely aware that the tone will be different from setup to setup, and that overdriving the tubes with high gain/volume will cause them to distort.

That's the basis for my question- does an effects pedal (if it's built into the amp and you have to "click" or "switch" it on I consider that an effect) overdrive the tubes to produce distortion or does it simply alter the guitar signal the way a transistor effect would- by introducing a square wave?

Would it be accurate to say that if you use a distortion pedal with a tube amp and aren't playing at high volume, then you aren't getting tube distortion, but rather transistor distortion?

Again, I'm not searching for a "sound", just an answer to a technical question.

Answer
That's a good question, I pondered the same thing a long time back. A distortion pedal does not overdrive the tubes of an amp; if this was the case then distortion pedals wouldn't work with solid state amplifiers! And neither is it producing a 'distortion tone' so to speak. Rather, it is distorting the waveform that is being produced, and the resulting wave distortion creates the 'fuzz' that we now call 'distortion'. Additionally, some do (as you say) increase the gain and then clip the waveform to reduce the overall volume, resulting in an altered waveform that emphasises certain tones and harmonics, though these are usually known as Overdrive pedals rather than distortion pedals (my preferred choice of pedal on top of a valve amp).

So in the case of your example, the guitarist is getting distortion introduced into the clean wave form via the pedal, which is either changing the wave form from one shape to another, or boosting and clipping it to produce an altered shape. Have a look at the following links if you want to know a bit more about distortion types and effects.

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