Having witnessed many a member submit articles on effect pedals, multi effects, and other tone-enhancing gadgets, I decided to submit my own article with my two-bits on the subject. First I have to note that I've studied this subject intensely and I am planning to open my own small home-based modding shop sometime soon. Many hours spent reading books on these things and many hours spent taking them apart to see how they work.
When it comes to buying effects, there are no static unconditional laws. I've heard many people say (friends, a few in music stores), for example, that Digitech X-series pedals are garbage. That's a lie right there, because what it all comes down to is: it's a matter of opinion, your other equipment (guitar, amplifier, pickups, other effects) and most importantly: your ear and what your "tone", to you, should sound like.
Some people like organic and smooth sounding liquid phasing because it has personallity and it's pleasing to hear, I don't, that's because I prefer a "meaner" tone so a metallic overpowering phase is what I root for. That little anecdote right there proves that some generic guy that says "Oh, digital effects sound like as warm as a dead polar bear so therefore don't buy them" just doesn't know what your talking about.
Allright, so to the meat of the subject. In this article, I will try to explain to you, the reader, what these effects do and what they don't do, how they affect the sound, and how the "marry", or go together in a chain. Sometimes, I will have to bluntly state my opinion, even though thats not what I'm wrting this article about (my opinion that is), thats because I have extensively tried the pedal and have either found a great flaw or because that effect has something that makes it for one reason or another, stand out, and when I mean stand out I mean it has, say, a feauture that most other effects of it's category don't have. In Pt.1, I will discuss the most basic and important effects, such as distortion, compression, and delay. Enough! I'll start with what these mysterious little boxes do to the sound.
Distortion works by making the sound wave more jagged and linear. Sound waves and your end tone are very close together, as a smooth round wave (called a sine wave) is synonimous to a clean sound and a jagged more square-looking one is synonimous to a distorted signal. Even though I do believe most people on UG have basic knowledge of what distortion does and what it sounds like, as I also beleive most people on UG have an IQ of at least 75...you never really know. So in case you don't (pat on the back and props to the noobs, I'm kidding about the IQ thing), it's what you hear in most punk songs and metal riffs and solos, even most practice amps have built-in distortion.
Very similar to distortion in many ways. First of all it can be obtained with some of the same electronic components and also it sounds very similar. Overdrive though, is the result of a "smoothed out", usually lightly distorted signal, so it souds less "in your face" and bluesier. Judas Priest, ZZ Top, and thousands of other musitians frequently use it, and since overdrive was first discovered by forcing an overwhelming signal through a Tube Amp, it's heard often since it's been around for so long. It's got "crunch" but not really "growl", even though you can get it to sound very mean if your equipment isn't limiting you.
This is probably one of those effects that many people know by name but many also don't have a good idea on what it does. Compressors should be thought of as tools more than as effects as it applies more to the dynamics and the nuance of your actual playing as it does to the tone. I've also seen many writers try to describe what it does but not making it clear at all. So here's what it does: it basically makes things that are loud softer and things that are soft louder, but it does this in a very controlled and mathematical manner. So it can be very helpfull in some situations, say if youre playing a solo where you do a lot of tapping or where you need sustain (off the top of my head, One by Metallica or Eruption by Van Halen), it will help you because when you're tapping, the notes aren't as loud as they are when they're strummed with a pick, so therefore the effect will make the tapped not-so-loud notes more audible.
Another use of a compressor could be to "keep yourself in threshold", say your're playing rythm guitar, you want to be clearly heard but you want your overall volume to crowd the rest of the band or the lead guitar. If you're using a compressor, your volume will never go over a certain level, and this level you define by a knob on the pedal itself. One downside is that if your equipment is generating any noise or hiss, the compressor will pick it up and make that noise louder. Result: louder noise. I use an Electro-Harmonix Black Finger and even though it cost me my first born son and my soul it's, as allways in my opinion, "the" compact-size compressor, there are better ones for sure but they're more expensive and usually rack-mount effects, and whats the fun in a rack-mount, eh?
Plain and simple, reverb simulates a three-dimensional real-time environment. Even though you can make a reverb pedal with almost anything metallic from an old spring to an empty beer keg, most compact pedals use digital circuitry to simulate halls, rooms, and other enviroments. What defines the virtual boundaries and physics on this enviroment are defined with the pedals knobs. The "type" of reverb, like say hall reverb or large room reverb is just a combination of how long the effect lets the note trail off, how abruptly it cuts off that note, how loud that note is, etcetera. Very usefull effect, it's also used on vocals, drums, keyboards...hell, just about any instrument can benefit from it's spaciousness and added dimension.
This effect is my holy grail and my vulgar display of power, I almost allways use light delay for my clean sounds and also for my solos. All this pedal does is digitally record what youre playing then simultaniously playing it back while recording the next sample. In other words, lossless perfect echo. It's not the kind of echo you would get, for example, by screaming into a big lake and then hearing your voice come back at you, because the recording is digital, therefore there is no loss and what you hear played back is exactly what you played into the pedal. An outstanding Delay pedal is the Boss DD-6, which on top of being virtually noise-free, offers the best variety of irregular delay effects, like reverse playback amongst others. If you set a delay pedal to a very short (say 70 milliseconds) time, then boost the feedback/repeat rate, you get a double-track effect, something very good to have if you're a lead guitarist.
This is the end of Part 1, soon to follow (might take a while, might have a full-time job soon) Part 2: Odd and Irregular FX.