Dan Armstrong was one of the music instrument industry's true originals. Most players only know him for the iconic, clear Plexiglas-bodied guitars he designed for Ampeg in the late '60s, played by Keith Richards, Joe Perry, Greg Ginn, and others, but the man was a fearless innovator who pioneered a number of ingenious guitar, pickup, amp, and effects designs over the course of his four decades in the industry. Amongst his greatest achievements—at least in the eyes of effects enthusiasts—is the line of guitar effects he designed for Musitronics, AKA Mu-Tron, in the 1970s. Musitronics was experiencing significant success with its original designs, but not making a great deal of money, as the Mu-Tron line was rather complex and expensive to manufacture. Dan Armstrong's small, economical, and cleverly named effects devices plugged right into the instrument jack (or amp, with some simple wiring modifications), and were deemed to be the perfect solution to the company's financial woes. Unfortunately Musitronics went under not too long after beginning manufacturing of Armstrong's designs, and as such, the manufacturing rights to these designs changed hands a number of times over the years, likely limiting their popularity. However, these tiny boxes have nonetheless developed a strong following in the guitar effects community due to their unique appearance and functionality, as well as their cool tones. Let's take a moment and examine some of effects designs of Dan Armstrong.
Orange Squeezer
Perhaps Armstrong's most well known and beloved effect, the Orange Squeezer is a compressor that has appeared on countless records by Dire Straits, Steely Dan, and others, with Mark Knopfler of Dire Straits being an especially enthusiastic proponent of this tiny orange box. The Squeezer has but one control, a switch to turn the effect on or off, but its simplicity and warm, musical compression are the keys to its success. Its pre-set compression characteristics are fairly modest (which seems like a wise choice for an effect with no parameter controls), so it doesn't offer the endless sustain and vicious squash of some modern compressors. The Orange Squeezer has a relatively subtle attack and smooth, blooming sustain, and unlike a lot of similar effects, it's relatively quiet. Because it's fairly well known and pretty awesome, the Squeezer's circuit has been cloned by a handful of modern effect builders in a much more convenient pedal form.
Blue Clipper
This pedal is another one that is well known in the effects nerd community, and its circuit is reportedly quite similar to the MXR Distortion Plus, with Armstrong himself stating that the Distortion Plus was MXR's attempt at making a version of his effect. This may or may not be true, but there are notable similarities between the pedals, both in circuit design and tone. That being said, the Clipper's full, somewhat dark sounding distortion qualities are quite distinct. Like the Squeezer, its only control is an on/off switch, but its permanent setting is a good one, and its fat, snarling grind sustains beautifully and responds quite well to the guitar's volume knob. Mark Mothersbaugh of Devo used to famously affix the Clipper directly to his guitar with tape.
Green Ringer
This miniature green box combined a low-gain fuzz tone with a cool octave-up, sounding not unlike an Octavia with single notes, but attaining a more ring modulator-like sound when given more than one note at a time. According to Armstrong, the Green Ringer was an improved version of the Ampeg Scrambler, which a co-worker had given him when he was working for Ampeg. He liked the effect, but felt he could improve upon it and make its octave component a bit more stable and predictable. After tweaking and experimenting with the circuit, The Green Ringer was put into production, becoming the first effect in Armstrong's guitar effects line. Its rather bright, cutting tone works best with neck pickups, like many other octave-fuzz effects, and it pairs beautifully with other Armstrong units, especially the Clipper and the Squeezer. For DIY'ers, BYOC even offers a kit that combines the Ringer and the Squeezer into one convenient pedal.
Red Ranger
Inspired by the Electro-Harmonix LPB-1, Dan Armstrong's Red Ranger was designed to give the guitar output a boost going into the amplifier, in order to enhance weak, low-output pickups, or to just give the amp's front end a push into overdrive. Armstrong took great pains to improve upon the LPB-1 concept, and in doing so, made his Red Ranger both quieter than its competition, as well as more versatile. The Red Ranger featured three modes, selectable via a small toggle switch, which was the unit's only control. The "Full" mode was a 13dB clean boost of the guitar's full frequency spectrum, while the "Treble" mode added another 12dB of treble boost on top of that. "Bass" mode punched up the low end by a total of 22dB, all without attenuating any treble or midrange frequencies. Robin Trower famously used the Red Ranger in Treble mode, typically towards the beginning of his signal chain, prior to his wah and fuzz pedals.
Purple Peaker
This effect was inspired by Armstrong's early experimentation with graphic and parametric equalization. In his experiments he noticed that, in many cases, boosts in specific frequency ranges tended to enhance the sound of an electric guitar, adding power and clarity. The original Peaker had three modes, with the "HI" mode offering a 12dB boost between 4000 and 5000 Hz for more presence and bite, while its "HI + LO" mode added an additional 7dB of boost around 200 to 400 Hz to add punch. The third mode, "OFF," was not quite all the way off, as it still added a slight overall bump in output, but without affecting specific frequency ranges. The tiny toggle to switch between these modes was the Peaker's only control.
Yellow Humper
This one has the funniest name of all of Dan Armstrong's effects, but regardless of that, it was originally designed as the bass version of the Purple Peaker, offering a little extra "hump" in the frequencies that tend to make the bass guitar sound nicer. Thus, its peak frequencies were around 100 Hz for the "LO" setting, giving the bass player 7dB of extra bottom and thump, and 2000 Hz in the "LO + HI" setting, giving an additional 10dB of presence and definition on top of the extra low-end beef. As with the Peaker, the Yellow Humper still offered a bit of flat boost and general signal enhancement when in the "OFF" position.
Dan Armstrong's unique effects designs have been reissued by a handful of companies over the years, as the manufacturing rights have changed hands more than a few times, but typically these reissues have been both overpriced and underwhelming. Vintage units are still available, but they often go for upwards of 200 dollars, and the jack plug design is less than practical for most players. Perhaps the best way for today's guitarist to get a taste of these effects is via the DIY pedal community, who have decoded most of the circuits and made schematics available online in various places. The circuits have also been cloned by a handful of boutique companies, who typically add some handy controls and put them in standard, modern pedal enclosures, which makes these fine effects much easier to use and enjoy.