Boost
Boosts (also sometimes called Overdrives) are pedals used to boost the signal strength, fine-tune the frequency response, or add solid-state clipping to get more/different distortion from a distortion stage, typically an amplifier's pre-amp. They typically cut bass or boost treble to get more distortion from the midrange and highs while leaving the bass less distorted. This gets a "tighter", less "muddy" tone. They may also feature adjustments to the dynamics of the signal, operating similar to compressors.
Most distortion pedals can function as boosts if their Drive is set low, usually incorporating tone-shaping controls.
While boosts have unique tone-shaping abilities depending on their circuitry, I tend to view them similarly to EQ. I cover tone-shaping by pre-EQ/boosts in Dialing in Distortion Tone.
Common Features
The common boost pedal has 3 controls:
- Drive/Gain - adjusts the level of compression or distortion it produces
- Tone - adjusts the frequency response of the signal to be darker or brighter in general, creating a rougher or tighter distortion from the amplifier respectively
- Volume/Output - determines how much the pedal boosts the signal to push the amp into distortion
Additional Features
Some boosts feature additional knobs or switches. These are usually to swap out the circuits of their high-pass or low-pass filters, altering their frequency response and thus changing the distortion. For example, some may have a "fat" switch that allows more bass to pass through. Some may have additional knobs, perhaps featuring complete Bass/Mids/Treble controls. Some switches may alter dynamics, such as using compression to lower transient noise or increase sustain.
Popular Models
The most popular boost pedal is the Ibanez Tube Screamer. Ibanez changed the components used as well as the circuit design throughout its history, and many prefer the original. While Ibanez has since released reissue and hand-wired versions of the original, the Maxon OD808 is identical to the original Tube Screamer without costing as much as Ibanez charges. Of course, the differences in tone are more likely noticeable when using these pedals for distortion rather than purely as boosts.
Many others have popped up that mimic the basic design of the Tube Screamer but tweak certain component values, making some strong changes to the tone. The basic principle is to use a high-pass filter to remove some low end and "tighten" the tone, while using a low-pass to trim some extreme highs, and a variable band-pass to dial in the resonant peak that defines the distortion tone. However, the Tube Screamer is almost always the basis of comparison, due to its high name and tone recognition.
- Airis Effects Savage Drive
- Maxon OD820
- Protone Attack OD
- Seymour Duncan 805
- Way Huge Green Rhino
Various treble booster pedals were quite popular in the 60's and 70's and remain popular for vintage sounds. These typically provided a high-pass or high-shelf filter with a variable gain and frequency. While I find these nice for a "quick and dirty" approach to dialing in a distortion tone, I prefer to use EQ or a distortion pedal where I have more tone-shaping control.