Select Effects: A Look at Some of Our Favorite Stompboxes

All electric and amplified acoustic basses, by definition, rely on one easily leveraged trick: The physical vibration of the strings is converted into an electric signal by means of a pickup (or, acoustically, a mic).
By Jonathan Herrera ,

All electric and amplified acoustic basses, by definition, rely on one easily leveraged trick: The physical vibration of the strings is converted into an electric signal by means of a pickup (or, acoustically, a mic). The properties of the physical vibration are essentially a result of the bass’s construction, the strings, and the player’s technique. While much sonic variety is available depite these relatively static properties, a pickup’s transduction from mechanical to electric energy opens up a seemingly infinite realm of sonic manipulation, as electronic circuits are capable of much more mayhem than anything possible through our physical manipulation of the bass. Arguably, our foundational role sometimes makes effects inappropriate, but there is no prohibition on free expression when the mood strikes. If you have never investigated pairing your instrument with one or many effects, you’re missing out on one of the most fun and potentially inspiring aspects of playing the instrument.

Having been responsible for a monstrous Bass Player effects cover story in the past [December ’06], and having written oodles of effect reviews, I knew going into this that I couldn’t be comprehensive. There are simply too many pedals on the market, and it would take a staff of dozens (or the miracle staff of Japan’s Bass Magazine) to accomplish anything meaningful out of so herculean a task. Pressed to think of an organizing principle for this article, I began with an extremely subjective premise. Of the many effects bass players use, there are three we seem to like the most: octaves, envelope filters, and fuzz. This theory has no empirical basis, so if you’re sitting on the john now, bummed that we’re not covering flangers, delays, bit crushers, or noise gates, well, tough cookies. I’ve also ignored great pedals like the Red Witch Factotum that combine several of these effects in one box. Yet, even when limited to those three types, a comprehensive article could still consume the entirety of this magazine’s editorial pages. Which gets me to my second subjective judgment call: I decided to review a semi-random grab-bag of pedals that range from obscure to commonplace. I also divided all of the pedals into three categories by street price.

Once the distillation was done, the fun part could begin: I got to play with the pedals. A lot. I used a handful of basses, including a Fender Custom Shop Pino Palladino Precision, Moollon J Classic 5, Fodera Emperor Standard, and an Ernie Ball Music Man Sting- Ray. I recorded the results with an Apogee Duet interface feeding Apple Logic, and I also used amps from Aguilar, Epifani, Ampeg, and Markbass. The internet is rife with demos and recorded examples of all the effects here—so instead of considering this article the definitive account of the effects that are out there, consider it a toe in the water, although one from a fairly experienced swimmer. Also, since I think it’s at best essential and at worst fascinating to understand how effects work, I’ve included general information about the function of the circuits themselves.


While a guitar player may have two octave effects in their pedalboard—an octave-down and an octave-up (or a pedal that can do both)—we bass players are generally more interested in the octave-down effect. Its application falls into two broad categories. Traditionally, the octave-down effect is mixed with a clean signal to produce a sound that’s much thicker. Pino Palladino is perhaps the best-known proponent of this sound, especially on his early work with Paul Young and Don Henley, where his fretless StingRay would be given extra heft courtesy of a Boss OC-2. A more recently popular approach is to eliminate the direct signal altogether, so that only the synthesized octave-down signal is heard. Since the octave-down signal has a characteristically synth-like tone (more on that below), such bassists as Tim Lefevbre, Steve Jenkins, and Janek Gwizdala have used it to emulate a synth sound.

There are two primary means of achieving an octave-down effect. First, it’s important to understand the relationship between pitch and frequency. Physics tells us that for a given audible pitch, say 440Hz, the note one octave down is exactly half the frequency, i.e., 220Hz. In recent years, a slew of digital pedals have emerged to accomplish this frequency division. These convert the analog signal of a bass into a digital one by sampling or digitally recording the signal. A processor then takes this digital information and divides the frequency. Finally, a digital-to-analog converter converts the signal back for further processing or amplification. Since digital processors are infinitely more flexible than analog circuits, digital octaves can perform many tricks that their analog brethren can’t, like polyphony and intervallic harmony. Yet, the analog-to-digital-to-analog conversion leaves a distinct imprint on the sound that some dislike.

Analog octave pedals are much simpler, but somehow more organically appealing. Almost all rely on the use of a basic electronic component called a “flip-flop.” A flip-flop circuit can be in one of two possible states. When a waveform crosses the circuit’s voltage midpoint in one particular direction (either up or down, but not both), the flip-flop circuit’s state changes, resulting in the production of either the positive or negative half of a waveform. Two things occur if the circuit is implemented correctly. First, the output of the flip-flop will be at a frequency exactly half that of the input, since it only changes states (creating half of a wave) once for each complete wave cycle of the input. Second, the resulting signal will be a square wave, since the flip-flop only has two states, positive or negative. A square wave is a far cry from the complex waveform of a bass’s output, so an octave pedal is one of the lowest-fidelity effects there is. But a square wave has a distinctly buzzy and hollow quality that’s popular in the synth world. The octave-down square wave can be filtered and shaped a bit, but it’ll never sound anything like an actual dry signal played down an octave.




Seattle’s 3 Leaf Audio named its Octabvre pedal after famed octave-aficionado Tim Lefevbre, and like its namesake, the consonant cluster at the end results in it being pronounced “Oc-TAVE.” The Octabvre is an exceptionally well-built box, with rugged, smooth-turning pots and a durable bentsteel case. To improve longevity and eliminate on/off noise, it uses soft-relay bypasses for switching. The circuit is original and inspiring; it’s essentially two octave pedals in one. The continuously variable tone pot changes its personality from a classic Boss OC-2 sound to one more similar to the old Mu-Tron Octave, which is grittier and harder edged. The mix control allowed me to blend in my dry signal, and the pedal has a sub switch, which disengages the dry signal to create that synthy square-wave tone on the fly. The pedal tracked reasonably well as is, and 3 Leaf says that a recent circuit upgrade improves the tracking further. Being able to blend between the two octave tones yielded a unique octave footprint, and I loved the ability to instantly switch to the sub-only sound. All in all, the Octabvre is an elite, cleverly designed octave that does all it needs to, exceptionally well.


The name Mu-Tron is hallowed in the halls of effect history. Founded by Mike Beigel and Aaron Newman in 1972, the Musitronics Corporation (or Mu-Tron, for short) designed a series of effects through the ’70s that have achieved mythic status, due in no small part to being favored by heavies such as Stevie Wonder, Bootsy Collins, and Joe Zawinul. While the Mu-Tron III envelope filter is perhaps its best-known effect (thanks largely to Bootsy’s heavy usage), the company’s Octave Divider is no less well regarded among vintage- pedal freaks. Musitronics co-founder and engineer Beigel is back with Mu-FX, building faithful reproductions of his original designs, although with contemporary manufacturing and a few useful tweaks. The Mu-FX Octave Divider combines an excellent-tracking octave-down effect with the classic “Green Ringer” distortion, which adds a fuzzed out octave-up signal to the sound. It adds both true and buffered bypass inputs and all the parameter adjustability you might want, including the ability to blend the dry signal, and a dedicated foot-switch (as on the Octavbre) for isolating the octave-down sound. It’s one of the most musical octaves I’ve played, with superb tracking (especially with its stabilize switch engaged) and a pleasant, gritty tone to the octave-down effect. The Ringer circuit adds a healthy dose of cutting edge to the tone. Construction is rugged, and thankfully the footprint has shrunk from the previous version’s pedalboard-gobbling extreme. Given Beigel’s iconic status in the field but the relative scarcity of his ’70s pedals, his return to the market is cause for celebration, as the near-perfect octave ably demonstrates.



Portland’s Catalinbread makes a whole slew of intriguing effects, often adding slight-to-extreme twists on the conventional. The Perseus is technically an octave and a fuzz, but its blend control allows for a no-fuzz sound, so it’s included here. The Perseus offers both one and two octaves down. I appreciated its small size, as well as its classy-but-flashy paintjob and durable metal jacks and switch. It seems to be geared more toward guitarists, in part because it includes a cut control that is essentially a highpass filter (for eliminating lows as it is turned clockwise). Also, its volume control has a huge amount of gain on top, perfect for overdriving the front end of a tube amp. Nevertheless, the Perseus tracked well most of the time, but certain low notes made it occasionally hunt for the right octave-down pitch. Those who are most drawn to the chaotic and inspiringly unpredictable end of the octave spectrum should investigate this Pacific Northwest maniac machine.

Street $130

The OC-3 has been around for a while now, and its ancestor, the OC-2, is legendary among bass players. It has the familiar Boss footprint and durability, and interacting with its relatively broad array of parameters is easy, although the limitations of its size are reflected in the tininess of the text on its panel. It has a host of cool features, some of which are due to its basis in a digital circuit. Its three modes include an OC-2 emulation, a polyphonic octave, and a drive circuit that marries the octave tone with a grinding distortion effect. Interestingly, the OC-3 has two inputs, one for bass and one optimized for guitar. Overall, the OC-3 is a good-sounding unit, although a distinctly digital-sounding one. Even in its OC-2 mode, it doesn’t sound much like the analog original, as its octave-down output has some of the distinctive glitch aliasing common to digital octave effects. I dug the drive setting for its sheer intensity, and being able to play octave-doubled chords polyphonically is cool, but overall the pedal is underwhelming from a pure octave perspective. Here’s hoping the OC-4 reintegrates the fab-sounding analog circuit that made the OC-2 such a winner.

UNDER $100

Street $68

Like all the Mooer effects, the Pure Octave is tiny. Having put together many a pedal-board, I can’t tell you how much I appreciate a small footprint, although in the case of the Mooer, it does mean cramming four knobs and a switch into a package about the size of a large pack of gum. It still felt quite durable, although the small plastic-shafted knobs used for adjusting the octave, direct, and octave-up effects aren’t all that confidence inspiring. Given its digital guts, the Pure Octave is capable of much more than the typical analog octave pedal. It can produce signals one and two octaves up and down, and its big white knob controls every permutation of those possibilities. While I didn’t love the pure octave-down signal, given its digital heritage, I was struck by how much diversity is available in a pedal of this type, especially when octave-down signals are blended with a light touch of octave-up. Those looking to create weird and interesting textures or extend their solo playing way up into the treble range would be hard pressed to find a smaller and less expensive option. Given the price, it’s a fun pedal with a lot of potential under the right feet.

UNDER $100

Street $25

At BP, we review products bearing in mind the price. If something is expensive, our expectations are higher, and if it’s cheap, we don’t mind a few shortcomings. The Behringer is way cheap, so I had fairly low expectations. Construction is decent, although not to the standard of some of the other pedals here. Its controls mirror that of the classic Boss OC-2 design, with separate knobs for direct, oct 1, and oct 2, although the UO300 includes a 3-way range switch that’s ostensibly for matching the pedal with the register of a given passage. With most basses, I preferred it in its lo setting. The digital Behringer does an admirable job, tracking fairly well. Its biggest let-down was its noise. Engaging the effect brought on audible hum that, while inaudible in a band context, was definitely annoying. All that said, if you’re a mere octave dabbler, there’s no cheaper way into the party.



Envelope filters combine two separate processes. First is the “envelope follower,” the portion of the circuit that produces a control voltage (CV) in proportion to the volume of the input signal. Think of a VU meter’s bounding needle, moving toward the red zone as the audio signal’s volume increases. Now imagine that this needle is monitoring a voltage—the envelope follower simply turns the signal’s volume into a voltage that tracks the dynamics of a musical performance. The envelope follower may respond instantaneously or slowly to changes in a bass’s volume, and this variable is inherent to the sound of effects that incorporate envelope followers. The devices often let you control sensitivity, governing the amount of signal necessary to trigger the effect.

In a classic envelope filter pedal—better described as an envelope-controlled filter—an envelope follower is paired with a lowpass filter, a circuit that eliminates high frequencies above a movable cutoff point. The envelope filter uses the envelope follower’s CV to slide the cutoff point across the frequency spectrum, and as this frequency shifts, we hear the tone color change. Additionally, these effects emphasize the cutoff frequency, usually adjustable with a “resonance,” “emphasis,” or “Q” control, causing the shifting filter to be more audible and dramatic. The cutoff frequency can either start low in the signal’s spectrum and shift higher as the input signal volume increases (creating kind of a “bwap” sound), or it can start high and move lower (creating more of a “dyoop”). This is the “up” or “down” setting of some filters.


Street $350

The SubDecay Prometheus DLX is perhaps the most fully featured envelope filter I’ve encountered. As is increasingly the norm in the synthesizer world, the Prometheus combines the unmistakable authenticity of an all-analog signal path with the flexibility of a digital control unit. The combination yields a pedal of remarkable diversity. The Prometheus is capable of the conventional bwaps and dyoops we commonly associate with envelope filters, but it also offers a low-frequency oscillator (LFO) that governs the filter behavior according to various standard wave shapes. The rate of the LFO is controllable via tap-tempo, and it can be subdivided in a number of rhythmically relevant ways. The multi-mode filter offers highpass and bandpass settings, and the resonance can go from subtle to extreme scream. An expression pedal jack allowed me to alter the LFO wave shape in real time or use the unit like a maxed-out wah-wah pedal. For the most comprehensive realization of the stompbox-size filter pedal, look no further than the well-made Prometheus DLX.

Street $280

Like the Prometheus, the Super Fatman combines an envelope follower with a multi-mode filter and an LFO with varying wave shapes. It offers even more control than the DLX over nearly every conceivable parameter, although it does lack a tap-tempo feature for syncing the LFO. For even more real-time control, a CV-in jack makes the unit compatible with synthesizers or CV-based expression pedals. I loved its squelchy, buttery sound, and the pedal is blessed with an extraordinary array of tones, from conventional envelope filter to total signal-mangling chaos. I thought of it as the Prometheus’ slightly crazy cousin; it offers a similar feature set, but with a slightly more experimental bent. Either way, the two top-of-the-market envelopes are so much more than the Mu-Tron of old. They are incredibly versatile tone sculptors that reward those seeking to remove their bass from its low-end support shackles.


Street $150

For a quick, durable, and excellent-sounding envelope filter, look no further than the sparkly-purple M82. Housed in MXR’s standard-size rugged metal box, the M82 offers intuitive control over all the relevant parameters in a filter pedal. It doesn’t do all the crazy LFO-based weirdness of the more expensive filters here, but what is available is classic bubbly funk-approved loveliness. I appreciated having a decay control to govern the rate of the envelope’s return to its starting point, and the sensitivity knob made it easy to dial in the sweet spot for a variety of basses with varying output levels. Also notable are the separate level controls for the dry and wet signals. Sometimes, envelope filters can suck out the low end as you engage the effect; by blending in some dry signal, I was able to preserve my signal’s beefiness without losing any of the filter gurgle.

Street $120

Source Audio takes a singular approach to effect design, relying exclusively on sophisticated digital circuits to realize its value-packed line of versatile effects. Source Audio effects can also be paired with its Hot Hand motion controller for real-time control of various parameters through body movement. By moving into the digital realm, Source Audio is able to leverage the flexibility of a microprocessor, and its envelope filter evinces this with a big variety on tap. The big central knob allowed me to choose among a variety of filter voicings, from traditional four-pole lowpass, a subtler two-pole lowpass, a number of interesting multi-peak filters, and more. Its construction is good, although I’m not a huge fan of the unconventional look and footprint. For a digital effect, the Envelope Filter is remarkably warm and gooey, although it lacks some of the beautiful nuttiness of many analog designs. It makes up for that with its sheer versatility and extensive control over multiple parameters, like sweep range, attack and decay amounts, and frequency. Even if you already have a more typical analog filter on hand, the Source Audio represents a useful new flavor to add to the arsenal.


The FX25B is recently out of production, but I included it here because they’re easy to find secondhand, and many stores still have some in stock. It’s the latest iteration of a pedal that has enjoyed a cult following for years, thanks largely to producer/bassist Bill Laswell, who favors the pedal for its ability to produce extremely deep dub-worthy bass when the sensitivity is set high. The “B” iteration of the pedal adds a blend control to preserve the low-end response while the unusual bandpass filter of the FX25 is doing its thing. I have a soft spot for this pedal, not only because it’s cheap, but also because it sounds like nothing else. It indeed is capable of deep dubbish sounds, but its distinctive quack is also a thing of beauty. It’s a finicky little beast, but when properly dialed in, there’s nothing quite like it.

UNDER $100


The E-H Micro Q-Tron is the cheapest of a series of increasingly feature-packed envelope filters marketed under the Q-Tron brand. It is as basic an envelope filter as they come, but that doesn’t mean it doesn’t sound great. It’s housed in a no-nonsense metal case, its knobs turn smoothly, and its switch engages with a confidence-inspiring thunk. It excels at classic Bootsy-esque quacks, and with the confusingly named drive (really sensitivity) rolled off, a deep and muddy sound is available with the flick of a switch. My big gripe with the Micro Q-Tron is the unavoidable volume boost I got when it was engaged. It’s not a big deal when stepping out and getting heard is in order, but the effect would be much more useful if it had some means of governing the boost.



Fuzz pedals are responsible for the most ear-shattering tones in our instrument’s palette, so not surprisingly, the technology behind them is designed to mangle an input signal. They all work on the same basic principle. The pedal’s output is a “clipped” version of the input signal, meaning it exceeds the bandwidth of its amplifying components and shaves the tops and bottoms off a waveform, resulting in something square-like in appearance on a scope. When a bass string vibrates, it is rich in harmonic content. There’s the fundamental frequency of the note played, but there’s also a series of frequencies of decreasing amplitude that are ratios of the fundamental. The specific combination and relative strength of these “overtone” frequencies give instruments their unique timbres. Clipping a signal introduces new harmonic content into the input, and when it’s performed on a signal already rich in harmonic content, the results are filled with aggressive character.

Fuzz is usually achieved with a circuit containing a small, high-gain amplifier (an op-amp, or operational amplifier) and a number of diodes that perform the clipping effect. The type and number of diodes used, and their arrangement within the circuit, gives each fuzz pedal its unique sound. Since fuzz tone is so dependent on the signal’s frequency content, EQ and other tone-shaping circuits upstream have a profound effect on a pedal’s sound.

One note: My price categorization breaks down a little in this section, mostly as a reflection of what’s currently on the market. There aren’t many fuzzes under $100 that I was interested in reviewing.


Street $250

There’s not much to complain about with the Dual Fuzz. First, its construction is excellent. I like the smooth, non-latching switch, the utilitarian durable metal case, and the nice, big knobs attached to buttery-feeling pots. Feature-wise, it offers all one could reasonably expect in a basic fuzz pedal, but with an added twist. In addition to the standard-issue blend, filter, and level controls, there’s the Duality’s cool trick: The pedal actually contains two discrete fuzz circuits, and the duality knob blends them together or allows each voice to play soloed. On the clockwise end is the more standard fuzz—it’s the more vintage-y sounding of the two. Go the other direction and a more insane, burly, and low-end-blessed fuzz tone emerges. I loved playing with the blend and the duality controls to dial in various levels of insanity.

Street $345

Given the simplicity of the features on hand, it’s hard to understand the Bassweet’s high price, but once I peeked inside, it made more sense. The neat and clever wiring, highend components, and overall solid feel convey a boutique vibe. With just sustain, tone, and volume controls on hand, operation is simple. The Bassweet is the pedal for fuzz fans who love huge low end. It’s shy in the mids and doesn’t cut that hard, but it’s got voluminous quantities of bass-frequency response. It also has an intensely compressed personality, so those after a dynamically sensitive fuzz (is there such a thing?) should look elsewhere.



While it’s not expressly designed for bass, I fell in love with the FE10. It’s curious why more manufacturers don’t offer the kind of semi-parametric EQ on tap here, given how frequency response affects the tone of a distortion or fuzz effect. The Ether’s construction is average, although there’s something beguiling about its generic look. Confusingly, expander controls the distortion amount, but otherwise the Ether is as straightforward as it gets. With the benefit of a semi-parametric EQ, you can get heretofore-unheard fuzz tones, from sucked-out-metal mids to an aggressive and biting tone that really cuts through a dense band. If you’re tired of an endless parade of fuzz clones, the FE10 offers something decidedly different.


The Bass Boost Fuzz is a straightforward fuzz pedal with an added twist: It doubles as a clean boost, with 21dB of boost! The build quality is excellent, and the panel text is laid out well and easily grokked. The tone control adjusts the cutoff frequency of a lowpass filter with a range of 1kHz–10kHz, a thoughtfully chosen spectrum that doesn’t dip too far into the midrange. I was able to get a variety of tones, especially when I used the blend control, but the Tech 21 has a fundamentally sludgy and thick personality that’s ever-present, regardless of adjustment. As a fuzz alone, it’s totally competent, if a little one-dimensional; however, factoring in the boost—and what it could do for the front end of an amp or other pedals down the line—it’s really like two pedals in one, and thus an excellent value.


Street $195

MXR is as mainstream a manufacturer as there is, but that doesn’t mean it doesn’t cook up some secret sauce. The El Grande is a super-handsome fuzz that performs its mission admirably. Construction is as sturdy as could be, with MXR’s characteristic small footprint and solid metal housing. I missed having a blend control a bit, but I was otherwise impressed with the pedal’s compressed and aggressive personality. At first glance, the deep button, which engages a preset bass boost, seems limited, but a trim pot on the circuitboard allowed me to alter the boost and frequency amount. Engaging it takes the M182 from mere grande to El Grande.

UNDER $100


What review of fuzz pedals would be complete without at least one iteration of the famed Big Muff? Originally released in the early ’70s, the Muff was one of Electro-Harmonix’s first big successes, and it has enjoyed many revisions over the years, with players often debating the relative merits of one generation or the other. Never originally intended as a bass-specific effect, the emergence of bass fuzzes over the past several years was cause for E-H to release a model specifically voiced for low-frequency response. Construction is excellent, with a metal enclosure, metal jacks, and a surface-mounted circuit-board. Its controls are simple, but it does have two unusual features: a dry out in addition to the effected output, and a bass boost switch. Having spent time with a variety of Muffs, the bass version is certainly in the ballpark of the original’s famously thick, compressed, and brutal sounds, and the bass boost certainly thickens its low-end response. It may not have the voodoo of its more precious out-of-production ancestors, but its sub-$100 price makes it perhaps the best value out there for a straightforward bass fuzz, surpassing the tone of some pedals twice its price.



Bass players love loop pedals. There are a few artists who have made extraordinary artistic use of them—Steve Lawson, Michael Manring, Janek Gwizdala, and Victor Wooten come to mind. But for the rest of us, loop pedals are an excellent solution to the vexing conundrum that bass has a sort of fun-ceiling when played unaccompanied. We thrive in bands, where our supportive role is best exploited, but our bands don’t rehearse at 10 am on a Tuesday (or some other random moment) when we’re most inspired to ’shed. Loopers allow us to create layers of accompaniment for us to practice, groove, solo, and generally have a great time. A few years ago there were just a few companies in the game, but digital recording and playback has become so ubiquitous that the modern-day looper has tons of options, from small and simple to elaborate and complex. If you want to get into the game, here are some great products to try. And, why not pair one with the cool new BeatBuddy ($350 street), a flexible pedal-based drum machine? (Street prices shown.)

UNDER $200

Boss RC-3, $180
TC Electronic Ditto X2, $180
DigiTech JMSXT JamMan Solo XT, $100
Electro-Harmonix Nano Looper 360, $135
Vox Lil’ Looper, $160

OVER $200

Boss RC-30 Loop Station, $300
DigiTech JML2 JamMan, $250
Boomerang III Phrase Sampler, $480
Looperlative LP2, ~$375
(check for details)