Guitar Gear

I had an interesting conversation with a friend today regarding the difference between overdrive and distortion. Talk about two terms that are bandied about interchangeably in the guitar world! If you ask ten different guitarists the difference between them you’ll get ten different answers. But a common theme you’ll hear is what each sounds like; in other words, you’ll get a much more qualitative description as opposed to a quantitative description. What I’ve been after is a much more objective description of each, but not necessarily too technical. So after talking about one versus the other, I decided to write down what we discussed, and throw my two-cents into the mix.

First, let’s look at the two terms, but from the perspective of an amplifier. The simplest explanation I could come up with is that overdrive, or in audiophile terms, over-powering, occurs when input gain exceeds the capacity of a device to handle the amount of gain thrown at it; in our case, a tube. What happens is that the smooth wave form that goes into the device gets “clipped” because the device’s input capacity is less than what is being thrown at it. Sonically, we perceive the result of this clipping as distortion. The higher the amplitude of the wave, the greater amount of distortion we hear.

But what about pedals? I’ll get to that in a bit, but I wanted to take time to clarify these terms. There’s been a lot of confusion about these two terms because they’re used so loosely, and oftentimes interchangeably. For me, I’ll stick with the audiophile’s perspective of overdrive in that distortion is the result of overdrive or over-powering an amplification device. A way to think about overdrive vs. distortion is that overdrive happens in the front-end (what you put in), while distortion happens on the back-end (what you hear).

But here’s where we get into a bit of murky territory, especially with pedals. Strictly speaking if we’re talking about overdrive as simply overpowering the front-end of an amp to make the tubes clip, the only pedal that is technically an overdrive is a boost pedal that takes your guitar’s signal and ups it voltage. But lots of manufacturers call their pedals overdrive pedals. In reality, most of those are distortion pedals – this includes the venerable Tube Screamer. OMG! Sacrilege!

So how do you tell the difference? That’s why I said we get into murky territory with respect to pedals, but as a rule of thumb, a distortion pedal will create a distorted sound irrespective of the amp. In other words, it’ll clip on its own. Put it front of the clean channel of an amp, switch it on, and it’ll create distortion. However, many, if not most, “distortion” pedals also provide a bit of gain boost to overdrive an amp. That’s where it gets murky, as most of the pedals termed “overdrive pedal” function as a combination of both overdrive AND distortion.

There are no real hard and fast rules, but in general most pedals that are commonly known as overdrive pedals (Tube Screamer, etc.) employ what’s called a “soft-clipping” circuit or transistor where only a small portion of the input signal is clipped. Most distortion pedals employ a “hard-clipping” device to severely clip the input signal to get that “square wave” tone. But as I said, there are no hard and fast rules.

So which kind of pedal to choose?

The pat answer is it depends on what you’re after with respect to your distorted tone. I know that this is a rather ambiguous statement, but again, there are no hard and fast rules. In the end, you should choose based on what sounds good to you. But here are a couple of guidelines:

• If you have a tube amp, and just want distortion purely from overdriving the tubes, then a booster makes sense. There are several kinds of boosters. Some boost only a certain frequency range, like a Fat boost that boosts the lower frequencies. I personally prefer a clean, transparent boost that has a flat frequency response so that the distortion that occurs is my amp’s tone. I typically use a booster in conjunction with my amp set just at the edge of breakup, so when I switch it on, not only will I get a volume boost, I’ll overdrive the pre-amp tubes; and depending upon how much gain I throw at the amp, I’ll get the power tubes working as well.
• If you want to add a bit of color and overdrive your amp, then a soft-clipping pedal like a Tube Screamer works quite well. Tube Screamer-type pedals typically give you a midrange boost that results in a much warmer and smoother distortion. Many also add sustain and a bit of compression to simulate power tube saturation at any volume. My Tone Freak Effects Abunai 2 is exceptional in this department, as is my Geek Driver (though the colorizing that this offers is completely different, but cool). Then there are others, like the Kasha Overdrive that add different EQ voicings as well as gain (you owe it to yourself to check that pedal out).
• If you want to get a distorted tone at any volume, then a distortion pedal is the way to go. There are lots of these on the market. My personal favorite (and the one I own) is the Creation Audio Labs Holy Fire which is actually a combination of both Overdrive and Distortion, having two circuits that provide both characteristics.

You can also chain overdrive and distortion effects to great success. I do this quite a bit because you get colors that you can’t get with just your amp. One thing that I do regularly is to use an overdrive pedal to push my amp hard, then when I want to get more tube compression and sustain, I slam the front-end with a booster (which is the last pedal in my chain). This doesn’t result in a volume boost because the tubes are already saturated, but you do get much more “gainier” sound, and that can really work with solos.

Again, there are no hard and fast rules. You have to play a lot of them to find your sweet spot. But that’s half the fun of it!