Photo: Alex Murphy
On a tremendous variety of amplifiers, effects, recording units, and more, you might spy a knob with a telltale four-letter word scribbled near it — “Gain.” This single control is incredibly significant when it comes to dialing in a desired tone for your electrically amplified instrument, as well as for recording said tone. While sometimes those gain and volume knobs sound like they’re doing pretty similar things, they are in fact quite different. Gain is the amount of input signal hitting whatever it is you’re adjusting. Turning up the volume makes the outgoing signal, essentially a complete tonal package, louder.
More gain is commonly associated with more grit, and a generally dirtier and more distorted sound. This is a result of “clipping,” where the high amount of input signal pushes the, say, amplifier, into overdrive, past a certain limit. If you look at an actual sound wave, clipping is the conversion of the normally sinusoidal wave into a square wave — the standard parabolic arcs suddenly cut off at right angles. We hear this as “distortion,” and it can enhance the presence and audibility of overtones coming from the instrument. As a result, lots of gain can sound thick and fuzzy, some can sound warm, and a little can sound sparkly clean. Most of these terms, however, are relative to whatever the gain parameter is actually adjusting. So let’s look at some examples:
Have you ever seen an old-school VU meter on a recording unit? Notice how the end of the meter usually involves red in some way? When your input signal’s gain is high enough, you’ll see the needle on the meter go into the red — and chances are, you’re going to hear some clipping. In some cases, that can be very desirable, and in others, not at all. Whatever you’re recording with should have some way of showing you how much signal is going into it. A recording unit or preamp might have its own gain control, which will allow you to directly control that — otherwise you’ll have to adjust the output levels of what you’re recording.
Guitar and Bass Amplifiers
Many guitar and bass amps have gain controls — multiple if they have more than one channel. In general, turning up the gain will increase signal volume and, starting at a certain point, induce clipping. This is especially true with tube amps (or hybrid amps with tube preamps), which are known for reacting dynamically to the amount of signal hitting the tubes. Solid state amps can react in such a way as well, but they are frequently cited as being “less organic” or “harsher” sounding (the upside is that they can produce much more wattage for lower cost and weight — but that’s a topic for another article). Some amps have little lights or displays that flash when the signal is being clipped — others leave it up to your ears to determine if you’re going into overdrive. A good rule of thumb for dealing with amps with separate gain and volume controls is this: for clean tones, keep the gain low and the volume high, and for crunchier, overdriven tones, turn up the gain and lower the volume to compensate for the increased signal (otherwise your overdriven tone will be much louder than your clean tone — unless that’s what you want). Turning the gain knob “to 11,” or “diming” it, will lead to the most distortion. Many guitar amps have separate clean and “dirty” channels, usually with individual channel gain and volume controls, connected to a master volume, allowing you to adjust these parameters as you like while retaining a consistent volume.
Peruse a catalogue with guitar or bass pickups (“pups” for short) and you’ll undoubtedly find many references to pickup “output.” Output is the amount of signal your instrument puts out (aptly named, it seems), and it is therefore intrinsically tied to gain. Pickup output is frequently tied to the number of winds that were involved in wrapping the wire component of the pickup around the pup magnets — more winds usually means more signal. As a result, “hot” or “overwound” pickups are commonly advertised, and are geared more towards thicker, heavier tones. If you’re a rock/metal guitarist or bassist and tend to use a lot of distortion in your tone, you’re probably better off slapping some hot, high-output pickups in your instrument. By contrast, low output pickups are better for pristine clean tones, though they can still be used to generate overdrive. A general rule to follow is that humbucking pickups tend to have higher outputs than single-coil pickups, and that active pups tend to have higher outputs than passive pups. Another thing to remember about pickups and gain is that the volume knob on your instrument can have a huge impact on tone — even if you have a super high gain pickup, if you turn the volume down, you’re putting out a lot less signal and, therefore, gain.
Effects Pedals — Boosts, Overdrives, Distortions, and Fuzzboxes
Gain with effects can be tricky. One might find it more apropos to look at “Level” knobs on pedals as being the source of gain, and they commonly are, as level determines the amount of signal going out of the pedal and into the amp. Some pedals have separate input and output knobs, allowing you to change how much signal (gain) hits the pedal itself, and how much then leaves after. Boost pedals generally function entirely as means of increasing gain, and are used to increase the amount of signal hitting an amplifier, pushing into overdrive, or making distortion even thicker. Overdrive pedals function like a standalone “dirty” channel for an amp, and can produce a wide palette of tones ranging from only slight clipping to rocking drive. Distortion pedals tend to be higher-gain versions of overdrives — they often can’t quite cop the gentle, subtler tones, but they can be used to produce thick, heavy tones with huge amounts of sustain. Fuzzboxes are a bit different beasts — they are also higher gain pedals than overdrives, but have different tonal qualities from distortions. An important note is that pedals in these categories tend to have very dynamic responses to an instrument’s volume knob; even if you’re cranking through a high-gain fuzzbox, if you roll back on the volume of your guitar, the tone can clean up immensely. All of these characteristics, though, depend greatly on the pedal you’re dealing with.
That’s all for now. Hopefully this brief overview of gain and some of its musical applications has been helpful to you. Tune in to Gear Up for more tips and information on how to tweak your tone.