Dynamic Range Compression is one of the most heavily used effects in music. However, when it is used properly, an audience shouldn’t be able to tell that it is being used at all. This is a guide to the different uses of compression by guitar and bass players and will cover information from basics to more advanced techniques involving multiple compressors.
What Does a Compression Pedal do?
Compressors are essentially automatic volume controls. Lower amplitude (quieter) frequencies are made to be louder and higher amplitude (louder) frequencies are made to be quieter. What many guitarists and bassists don’t realize is that they are probably already very familiar with compression as an effect; It is one of the positive side-effects of overdrive and distortion, whether the dirt comes from the amplifier or from their favorite stompbox. Distortion and Overdrive will boost the input signal and increase its amplitude, then clip any wave peaks that are above a certain amplitude, decreasing the range of dynamics for the guitar’s signal. This amplification of quieter frequencies gives the guitar more sustain. Compressors achieve this same decrease in dynamic range and increase in sustain without distorting the guitar signal in the same way a distortion or overdrive would.
Why Use a Guitar Compressor?
If you’ve ever played a live gig, you know that no matter how much you practice and how good your songs are, the audience will only enjoy your set if the levels are set properly. The easiest way to have your sound mixed well is to deliver a consistent SPL (sound pressure level) to the front of house so that the sound technician can do their job more effectively. As somebody who has worked as a sound technician, I will tell you from experience that chasing a performer’s changing dynamics up and down the fader so that they can be heard but are not overpowering is incredibly difficult. This is especially true with guitars, because often guitars will not be able to carry the same volume in the bass and treble frequencies as they will in the midrange. Having a dynamically compressed signal drastically reduces this problem.
Compressor Formats & Controls
Compressors come in many forms, from pedals to rackmount units to digital plugins for your favorite DAW. Most guitarists and bassists favor compressors in pedal form because they allow for easy and on-the-fly tonal customization, as well as the option to turn them off as they please. While the number of parameters that can be altered changes greatly by model, there are four controls that are commonly found on compressors:
- Level: This control is essentially a volume control for the compressor.
- Ratio: This control changes the amount of compression applied to the signal.
- Attack: This control alters how quickly a high-amplitude signal is compressed
- Release: This control determines how long the compressed signal is affected by the compressor
Compression in Guitar Signal Chain
There are two main contrasting opinions about where to place compression in a signal chain of effects pedals. The most popular placement of compression is before any overdrive or distortion pedals. This makes sense because it ensures that a guitarist may switch between different guitars with different pickup outputs and retain consistent operation from everything after the compression in the signal chain. For this purpose, I recommend setting the Level control higher with a lower compression ratio, a slower attack, and a longer release. This way, the individual tonal characteristics of different guitars remain audible, due to the lower compression ratio and slower attack. The higher level control and longer release control settings will ensure a more even amplitude through the rest of the signal chain.
The other place in the signal chain where compressors are commonly found is directly following any overdrive or distortion pedals. For this setup, I would recommend setting the level control to cut the volume coming out of the drive pedals, setting the attack control at a medium setting, the release control to be medium to slow, and the compression ratio higher. Fans of this setup use it for several reasons. First, it allows them to control the amount of drive from the pedals by using the volume knob on their guitar, but still retain the same overall volume due to the compressor. Second, by cutting the overall level of the signal, they can set the master volume of their amplifier slightly higher, which allows more current to flow through the power tubes providing a better bass response. Finally, the most important reason for doing this, is to allow the player to use a compressed, easily mixable tone for rhythm playing, and a dynamic, cutting tone for lead playing. By switching off the compressor which has been set to cut the signal, players will get both a boost in volume and dynamic contrast, both qualities that are ideal for lead playing. Also, because many compressors clamp down on high frequencies, players may experience a brighter tone during solos, which makes their playing sit better in the mix with a full band.
Players may even want to combine these two uses of compression by using two compressors on their pedalboard. As always, when adding more pedals to a board, especially pedals that have an effect on the amplitude of the signal, background noise can become an issue. There are several ways to help this problem. By using an isolated power supply, higher quality cables, and possibly a noise gate, noisy pedalboard setups may be quieted down.
Compressor Pedal Recommendations
Approximate price: $199 direct from Wampler
This pedal has five controls which allow the player to dial in the perfect sound. The tone ranges from squeezed to transparent. This pedal represents amazing versatility and has plenty of aptitude for tonal customization.
Approximate price: $199 from Keeley
This pedal represents some of the finest sounds available in stompbox compression. The 4-knob compressor is well-reputed for its transparent tone which preserves the tonal characteristics of anything preceding it in the signal chain. You won’t know when it is there, but you will know when it isn’t.
Artists who use: Chris Allen
This is one of the most popular and widely used compressors. While it only has two knobs, output and sensitivity, it is a very versatile pedal that has a signature sound. This compressor is the ideal pedal to nail down the round clean tone reminiscent of John Frusciante, or to get the spanky clean tone that is perfect for country runs.
Artists who use: Caleb Followill, Sam Halliday, Noel Gallagher, Eric Johnson, Pete Townshend, David Gilmour, Emily Kokal, Jim Messina, Nick Allbrook, Kevin Parker, Anthony Phillips, Adam Jones, Rabea Massaad, Fito Cabrales, Peter Holmström, Sergie Loobkoff, Bert Lams, Paul Wilson, A.J. Dunning, Ricardo Mollo, Hernán Langer, Buzz Osborne
The SP compressor is a very good sounding pedal, similar in functionality to the DynaComp. The SP delivers a strong punch with up to 15 db of boost available as well. The miniature size makes it ideal for players whose pedalboards are already crowded.
Boss CS-3: The CS-3 is another widely used compressor pedal. This pedal features four knobs for tonal customization and versatility. It is also packaged in a bomb-proof boss pedal enclosure which gives it rugged reliability. At $99 new, the CS-3 is one of the best deals on the market.
Artists who use: Jack White, Mike Einziger, The Edge, Synyster Gates, Vince Gill, Ean Golden, Paul Gilbert, Andy Bell, Neal Schon, Marc Rizzo, Lee Ranaldo, Matthew Healy, Adam Hann, Zach Abels, Nels Cline, Ira Kaplan, Dave Knudson, Paul Waggoner, Dustie Waring, Bruce Springsteen, Legowelt, Billy Martin, Luke Reynolds, Adam Franklin, Nick Steinborn, Zach Myers, Peter Koppes, Richard Hawley, Laurie vincent