Introduction - Guitar Signal Compressors
This is a brief guide to the mysterious world of guitar pedal compressor options.
I am writing this specifically in response to helpful guides and feedback concerning the MXR Dyna-Comp, one of the best-known and loved, small floor compressor pedals. I have never owned one but sure have heard plenty. I own a vintage MXR Phase 45 in "block letters," for which I paid a premium because the mid-range mojo has a great balance between thrust and swirling, high-level harmonics. I do understand and empathize, recognizing the "magic" in some vintage equipment and agree they can be worth the price "enhancing your life," but otherwise, let the buyer beware whether others can hear the massive differences in cost.
Dyna-Comps work, but frankly, are fairly crude by comparison to dedicated rack-mount and even one floor pedal compressor some regard as "boutique" grade, one I will highly recommend very soon in this and have been using myself for nearly two years. Compressors and limiters are all designed to pleasingly "squash" the frequency range to reduce human ear fatigue, add note and chord sustain and frankly, sound louder than the next guy with largely the same amplification. Louder is always better, right? Not really! Guess which music radio stations tend to be the more popular ones? That's right, usually the stations that compress EVERYTHING so they sound louder, even though compression can destroy the subtlety of carefully recorded and mastered sonic art. We do not love those radio (and now, Internet-streaming) stations, being knowledgeable musicians and listeners, right?
The One-and-Two Dial Options
The MXR Dyna-Comp is a righteous, effective pedal, although many people on this site and others are paying prices for vintage units that are comparable to far better quality rack-mount and floor pedal compressors that would be far better for their sound and needs. Don't do that if you really need a flexible compressor unit, unless you have meaningful, prior experience with variety of studio compressors and floor pedals, and you find a Dyna-Comp that is indeed SO special it's worth eight or ten times the price of an "ordinary" Dyna-Comp. Price doesn't always equate to quality; price is usually based on perceived value and rarity.
I'm with you in practice, Dyna-Compers, even though I don't own one. My personal one-dial option(s) are 21st century production but are now regarded as vintage, being out of production. They are tube-driven OD/overdrive units by Damage Control. The Damage Controllers are now affiliated with Strymon pedals. (Really like and recommend my new-ish Strymon TimeLine delay, by the way.) Damage Control engineered several pedals equipped with a compressor dial. These single-control "squash" circuits, like Dyna-Comps, actually work very well. Those units were called the Womanizer and Demonizer - yes, they are different, mostly in intensity - and the compressors moderate the additional drive and EQ powered by two 12AX7 pre-amp tubes. They are adjustable over approximately a 280 degree range. They made another with that dial called Liquid Blues, primarily designed for producing Class A distortion. I bought the other two for their excellent 112 (Woman-) and 412 (Demon-) cabinet emulation-out jacks.
The Dyna-Comp and other "simple" compressors have one or two dials doing the same thing, reducing the dynamic range of the signal. For me, having the single, compression adjustment dial on the Womanizer and Demonizer is effective and adequate to the task of simple tone enhancement. It's a "taking away," not an "adding to" the signal so much, although adding perceived loudness and sustain deceptively seem like additions. It's kind of a cheat, really. You've heard of "optical illusions?" Artificially compressed signals, particularly those that are over-compressed, are sonic illusions. Beware.
The Multi-Dial Compression Options - The FloorQ
Won't hide the secret any longer: after sampling several devices and studying a lot of Internet video and product reviews, I bought a floor demo model of a Joe Meek FloorQ optical compressor pedal on eBay, saving about $80 over the $249 street price. Essentially, the designers re-purposed the studio rack-mount effect circuitry in a floor pedal-sized form factor. Some of the same controls on a standard rack mount compressor, like Joe Meek's 3Q or the venerable Universal Audio 1176, stand tall among many studio-based options that have made their way into home studios and portable, rack-mounted rigs for professional, gigging musicians. The FloorQ shrinks them into a unit also with a JFET powered, Class-A pre-amp built-in, an amazing feature, allowing users to balance and equalize signals between amplifiers, using labeled Input and Output boost circuitry. The dials manipulating the compression algorithm in the FloorQ include the Slope, Attack and Release controls, just like rack-mount units.
Look up "dynamic range compression" and similar terms on Wikipedia and other audio and psycho-acoustics sites, discussing how signals can be adjusted so the unique hearing and interpretation devices known as the human ears and brains regard some signals as harsh and fatiguing, yet can be manipulated into recognizing those same signals and others as being sweet and endlessly wonderful. The articles better describe Compress, Attack and Release-type controls in particular, adjusting how quickly dynamic changes in sudden attack are manipulated and how slowly or quickly they are processed through the compression algorithm and then released. Try setting Attack and Release values opposite of each other, the typical method for most compression designs, but try everything else as well. I think of these as the sonic versions of changing the number of holes and hole sizes in a sieve or screen through which the signals are poured and narrowed.
The four-dial, Keeley Electronics C4 compressor begins approaching the FloorQ in more-precise usability. It does not contain the internal, Class A pre-amp which encourages volume balancing between amplifiers and other output loops, such as a house PA system. I also use mine slightly boosting ultra-low (one watt or less) power amps like the excellent Red Iron Amps Lil Mo' and Surprise Sound Lab RockBlock amp/overdrive pedal. Each are around $400, and have been reported to save marital stress providing satisfying, quiet storms of overdriven tone for small rooms.
Another floor pedal option with unique controls is the Pigtronix Philosopher's Tone, which is largely designed for dialing up "sustain" easily, and what they label as "grit," which can be manipulated with the other controls reducing or increasing overall distortion. This is far beyond the typical role of an audio compressor, but has proven enduring and popular. Less commonly seen, also by Pigtronix, is the Philosopher's King, with a compression "one-dial" control as well as a "sustain" dial, along with far more exotic synthesized-distortion and envelope modulation. Hybrids will continue flourishing.
Last, along with many smaller devices offering signal compression circuits, including Moog and other synths, are the newer mega-boards also including a wide range of amplifier models, modulation effects and many more. Compression algorithms and related features are but a few of the hundreds, and are nearly always included. Popular choices are produced by Line 6 in their POD and HD POD series, and M13 pedal assortment. (I am relatively happy with my POD HD500 by Line 6, including the simple, compressor percentage adjustment dial.) The TC Electronic Nova System, Roland MIDI and many other complex, multifunction stomp boards and dials include compression controls, frequently with internal adjustments modifying the algorithm, adding or deleting distortion and other attributes. Using all-in-one pedal board systems is very convenient and seductive since they sound pretty good, are usually upgradable via USB or Ethernet on computers, and sure are easier on the roadies, probably meaning you and your friends.
Conclusion: Use a Light Touch; You're Compressing Sonic Fire (and Water, and Air!)
If you want a single floor pedal for effective, highly adjustable compression for your home studio or gigs from club to arena, I recommend a Joe Meek FloorQ. It's does the most for the least at this point (July, 2012), allowing a more intelligently textured, sonic fabric rather than imposing its own, strong effect that may bore or alternatively, grate on a lot of ears. Use a light touch with the Joe Meek and all compressors, distortion and most effects, unless bleeding ear, "over-the-top" sound or swampy mud is what you are aiming towards. If you can get people paying to listen to your wall of noise, good for you. Watch, listen and learn if they run away, screaming and holding their ears in pain and disbelief.
Sonic fire, as well as tones reminiscent of gentle water and fluffy clouds in air, can be more easily accomplished than ever with modern guitars, pickups, amps and effects. Interpret my words about compression and other effects as you will, but in the end it's your art. Even Mozart, the person many regard as the greatest composer in the Western World, was said by his King at the time to have written and conducted an opera the night he attended that was good, but with "too many notes." Everyone's a critic...and some of them can chop off your head (or career). It doesn't mean they are right, but you should consider the possibility! You need to play for and please "your" audience, even if it's just yourself and your long-suffering pets.
Having and intelligently using good signal compression is required musicianship as well as competent audio mastering, nowadays. Even acoustic guitar players have caught on and use compressors in acoustic amps, fancy PA systems from Bose, JBL and others. Singers have learned about the value of artfully using compressors sweetening their voices, as well. We stringed-instrument players have the great benefit of a long history that began with the Greek philosopher and mathematician Pythagoras (who lived around 570 to 495 BC), who devised the "Theory of the Monochord." In it, among other things he discovered there is a repeatable, mathematical ratio where halving a string and then plucking it would raise the sound an octave higher (playing at the 12th fret for most of us). Musical notes can be translated into mathematical equations. Bringing ancient Western knowledge up to the present, compressors can and should be used - fairly precisely and repeatedly, measured by a mark on a dial or ultra-fine measurements through an oscilloscope - squashing down, sweetening up and airing out tones, making them sound better. Please join me using the power wisely and with a gentle, light touch, hearing subtle differences through which humans have been entertained, elevated and completed for more than two thousand years. Don't spend too much, and Happy Compressing!