version 11/09

Subzombie TM Fuzz/Distortion Device Owner's Manual

Connection
Connect Guitar or other Instrument to IN/POWER jack -- this also powers up the unit when using batteries, so remove this plug when not using.
Connect OUT jack to amplifier. May remain connected.

Observe all safety warnings with regards to external equipment.

Battery Installation
Battery is 9 volt type: US "9 volt"/International "PP3"

Remove 4 screws from bottom of enclosure. The battery goes in the lower corner of the enclosure between the footswitch and the OUT jack and connector clip best faces the corner. Reassemble carefully -- do not cross-thread or overtighten screws. The cover go on either direction but the edges will align better in one way: note the markings on the inside of the cover.

A 9V power adaptor with negative tip, positive sleeve (industry standard) may also be used. This must provide regulated voltage (i.e. be for quality audio applications, Boss or equivalent). The brightness of the indicators little indication of the strength of the battery. The D2 and D3 indicators are NOT affected by battery strength except when complete battery failure results. Operation is "OK" down to about 7.5 V below which the tone, gain and especially the effectiveness of the controls will degrade.

Operation: Non-technical version

It helps to understand how Subzombie works, but the controls are simple enough to just explore through sound as well.

The MIX knob is the main selector of fuzz and distortion sounds. This also changes the volume so be sure to adjust VOLume accordingly, rather than avoiding whole ranges of sounds. Start with HI centered, where it does the least. HI is not a normal tone control, it varies the fuzz characteristic as well, and can cut or boost overall highs depending on the combination.

Tip: If playing and adjusting, try a high gain setting to adjust but then turn it down for normal picking... and be sure to try any interesting sound at different gains, too.

The Distortion Signals and Fuzz

This pedal uses a cascade or series of 3 distortion generators. #1 is the main one in that it produces most of the gain (including its adjustment). #2 and then #3 simply add a small amount of gain and distortion each. #1 also has more an overdrive character, while the others are a harder distortion as well as having more gain. The way the LEDs illuminate also shows this difference, with LED #1 varying over a huge range, sometimes dim, sometimes the brightest.

An antiphase mixing effect produces a subtraction or partial cancellation of the signal, leaving behind something fuzzier than it started with. To put it even more simply, it sounds like the signals fight or clash, "anti" or inverted indeed. This kind of mixing also sounds little like a "mix" of more than one signal, and more like a mutant or warp. Both the overall fuzziness, and where in the dynamics and tone of the instrument signal the fuzziness occurs, can be altered. The source distortion signals retain good dynamics and tone of the original signal, which results in a minimum destruction of the original tone and instantaneous response while still producing a high fuzziness level.

In Subzombie, to simplify things, signals #1 and #3 are always in phase, while #2 is antiphase, or more accurately, the minority phase (when #2 is dominant, the others seem like the ones out of phase). Regarding overall fuzziness, #1 and #3 add together in their opposition to #2. The MIX control includes ranges emphasizing 1, 2, or 3 of the distortion signals, but always at least slightly mixed.

Controls

GAIN - controls the amount of distortion and sensitivity. The total drive to the distortion is also a product of the instrument level. Also, the extreme settings of the control cut bass. Positions approaching minimum (below 8:00) cut bass for articulation beyond mere low gain, and high settings would otherwise get too muddy.

VOLUME - is used to match the volume to the bypassed sound and compensate for changes in volume due to the other controls.

MIX - is the main determiner of the sound characteristic. It is mirror-imaged: starting in the center, you can go either left or right for two flavors, but with the same type of variations. On either side, a fuzz region is marked Z (approx.) found where the in-phase components (D#1+D3) cancel partially against the out of phase one (D2). In other words, the sound whacks out.

HI - also contributes to the mixing, but relative to MIX, again mirror-imaged. It cuts highs of one or more of the distortions as indicated by the -1 and -3 markings. The center position is the start point and results in minimum alteration of the sound. At MIXs towards +1 or +3, the highs are smoothed in two different ways by turning HI to either side and treble is reduced somewhat overall. At other MIX positions overall treble tends to be boosted by the action of HI, or midrange is cut.

The ranges of MIX are:

+1 - emphasizes the lower distortion(/overdrive) #1 but #3 is still included, and since #3 still has more gain, it's enough to balance them into a mixed type of sound at lower drive levels. There is still some of #2, but even lower; as MIX is varied away from its endpoint this changes rapidly and the sound becomes leaner. Turning HI towards -1 cuts treble most on distortion 1 but also some on #2 and #3. -3 only smooths the more distorted #3's contribution to the background.
Z (left) - a fuzz range emphasizing D#1, with #3 again substantial due to its gain, varied against the ANTIphase #2. The strongest cancellation can be tuned to #2 against one of #1 or #3 individually, or against the sum of #1 and #3 combined (further towards +2). Turning HI to either side is more dramatic here as it changes the balance of the antiphase effect, and can affect mids somewhat as well as treble. Initially turning HI leaves the bass alone, but if MIX is then turned towards +1, your original MIX balance is shifted up through the midrange and into the treble, altering everything else instead. HI towards -1 cuts treble most on distortion 1 but also on 3, while -3 only affects #3, smoothing and deemphasizing this higher gain level portion while still affecting the overall phase balance.
+2 - emphasizes distortion #2 but with substantial amounts of 1 and 3, shifting between the latter over the this range. #1 and #3 are out of phase with #2, but bracket #2 in gain level so that aspect of difference is reduced. HI produces a subtle brightening of the sound, with a few useful variations.
Z (right) - is similar to the left Z, but in emphasizing distortion 3 in volume as well as gain, the effect of distortion 1 is more subtle. On the other hand, #2 and #3 are more similar in tone, and can cancel more completely at high gain, still exposing the influence of #1. HI is similar, but this time trying HI to a side will shift interesting MIX settings towards +3, and vice versa. With HI to the opposite side of MIX, towards -1, it only affects #1, but towards -3 also affects #1 somewhat.
+3 - is similar to +1, but emphasizes distortion 3 in volume as well as gain.
dots (originally G's) - indicate GATE versus Zombie inflections. The strongest "swell" effect, especially at high gain, occurs at a MIX slightly clockwise of the strongest Gate effect, which is most dramatic at low gain (although the settings overlap and are barely different on the left side).To find a Gate point, turn up the gain but turn the guitar down. Adjust the MIX for least noise. The strongest gating occurs with HI centered, but gating over a limited frequency range is also possible.

With typical guitar levels, GAIN is centered on crossing the dynamic threshold where the three distortions are most different and fuzz settings provide a "vocal" emphasis. Lower GAIN settings shift this emphasis into the attack of notes, and higher settings go "over" the dynamic threshold into either complete turbulence or smoothness with a "swell" effect on sustained notes.

TONE (optional SE-4B version) -- cuts highs of the total mix signal and also slightly enhances bass, or at full clockwise these effects are bypassed for maximum volume and presence (see below).

In the standard version, VOLUME also changes the tone somewhat in accordance with the internal TONE trimpot (see below).

The footswitch enables the effect.

More on How It Works
A parallel mix of three distortions may be produced simply by using a cascade (series) configuration:
                               

The example to the right shows graphically a simplified example of how distortion mixing works to produce a fuzz sound. "A" is the positive portion of a distorted wave. "B" is more distorted (more gain) and inverted (upside down). "C" shows how these add together, forming a harsher, more complex waveform. Or rather, B subtracts from A by its magnitude. This still only hints at the complexity. For one thing, Subzombie uses three distortion signals with gradually increasing levels of distortion and the middle level is inverted (reverse phase or polarity) whereas the lower and higher level of distortion add together in phase. Perhaps more important, the differences between these distortions change dynamically, for example at some point the lower distortion signal is clean, while the higher distortion signals are slightly distorting.

But waveform analysis is a limited way to understand how this sounds. Essentially, when you subtract a cleaner signal from a more distorted one, you subtract the cleanness and leave only distortion. The various signals cancel, oppose, or "fight" one another and sounds like it, due to the more jagged waveform. Also it can sound like like the higher distortion subtracts distortion from the lesser distorted signal, making what sounds like a mix of a very clean and very distorted sound, when not one of the individual distortion signals are completely clean or completely distorted. The differences between fuzz tones are a lot more complex than simply how harsh they are. Imagine 2 sounds, one harsh and one not. With normal distortion, the sound gets harsher and louder when one plays harder, and decays towards cleaner and quieter. But Subzombie can reverse part of those tendencies. The sound can get harsher or louder as a note decays, or one plays softer or turns down guitar volume. These dynamic characteristics can be shifted strongly within the distortion range with the MIX control, and over different parts of the tonal spectrum with the HI control. However, Gain controls where these ranges of distortion lies within the dynamic range of the guitar. The strongest fuzz settings produce a kind of vocal peak. In analogy, think of a hill you're driving over. The guitar and Gain level controls how far over this hill you're at. A low gain, the attack surges up the hill but doesn't reach the peak before rolling back. At high gain, you might be past the hill, but as a note decays it backs up and begins to rise up the hill, producing a "swell" effect. Therefore, the attack, decay, or sustain portions of guitar-type sounds can be emphasized.

The internal TONE trimpot

Standard 4-knob version: AUTO-TONE
VOLUME changes the tone somewhat in accordance with the internal TONE trimpot, allowing a pre-set compensation for the range of tones going from slightly dark to quite bright. A VOLUME control position slightly above midpoint results in the most bass enhancement. The louder MIX settings match to the clean sound with a low VOLUME setting, but fuzzier, brighter mixes are quieter and therefore result in VOLUME settings closer to half up resulting in more bass enhancement. The highest VOLUME settings result in less bass enhancement as is appropriate for volume boosting or driving an amplifier into increased distortion. The trimpot calibrates this effect. The default setting is subtle but present; increase it for a bassier sound; minimize it for sounds that "cut through" more, for example when driving into a dark sounding or distorted amplifier.

Adjusting instructions:
The TONE trimmer is a small potentiometer located on the circuit board (see battery installation instructions above to open the unit). Note: this control is delicate and therefore, if you do not feel comfortable with your ability to adjust it, it is suggested you leave it alone. Some force and a small screwdriver will be needed to turn the control, but do not apply excessive downward force as this may break the control or excessive rotational force as this could break the "stops" of the control. Subzombie is normally shipped with the control near center so it should initially be able to turn in either direction.

The "knob" on the trimmer is tint dial with a screwdriver slot in the center. Turning it clockwise increases the depth of effect on the associated external control and counter-clockwise minimizes it. For black dial versions, the "pointer" is between two dots opposite some numbers and the nearest side of the board is the "top" of it's clock-face. It is not intended for public consumption, adjustment is subtle on the low end, and sharp at high settings, and the maximum setting is not intended to be used.

Tone knob versions (SE-4B, after 11/09):
This trimmer varies the ratio of the bass enhancement effect of the external TONE knob to its primary high-cut effect. Turning up TONE bypasses the bass enhancement, center has most of the bass, and TONE down emphasizes the high cut. The trimmer positions are:
full counterclockwise -- minimal bass enhance, maximum volume and isolation of the high cut.
noon to 1:00 -- subtle but slightly deeper feel
2:00 -- about the maximum to work as intended, noticable.
above 2:00 -- may affect the sound even with TONE at maximum, and since Volume needs be set higher, the high-cut seems deemphasized. VOLume taper affected, not a problem but may confuse adjustment.
3:00 or higher -- may cause unintended distortion with VOL and Tone both at maximum.

Signal Characteristics
The input is designed to allow high output pickups, but high level boost devices connected to Subzombie's IN may cause adverse sonic effects because the first stage is a medium-level boost stage already. It may also then become impossible to match levels. When driving the input with distortion pedals, most do not have such high output levels, and can be turned all or most of the way up without any issues. Best signal-to-noise ratio is achieved when the guitar volume is set to maximum, although turning down the volume to intentionally change the sound is very effective.

The maximum output level is generous, but volume is reduced with many mixes. These tend to produce a "spiky" shaped waveform with a higher peak level than the apparent volume may indicate. The output is wide-bandwidth rather than sharply filtered to smooth the sound like many distortion pedals, to increase versatility. There is some filtering, but this is aimed more at making the signal easier to amplify than audible results within the range of most guitar speakers.

TIPS
Start with a clean amplifier setting, at least until you get more familiar with the controls.

The only problem with the most extreme settings is that they are, well, extreme. The first step is to learn to tune them, the second is to learn to detune them.

Be sure to try your guitar's TONE control.

Combinations
Subzombie is an excellent building block towards more complex sounds due to its controllability and capabilty to be sonically neutral. An equalizer following its output is a natural combination which allows more bulk tonal flexibility and the fuzz's settings to be manipulated independently of final tonal contour. Distortion devices and amplifier distortion can also be stacked; a big advantage is that lower gain settings can be used for each box. Distortions that limit the dynamic range too much will produce poor results driving SZ's input -- overdrives work better in this position. Note that distortion is only part of many boxes' sound, they may contain strong tone shaping EQ and filtering; this can be useful or problematic. Some distortions may work well following SZ when set to low gain because they smooth the sound. Tube-based distortions and amplifiers are also a natural combination as they add that certain quality. Compressors driving the SZ input are surprisingly effective, with their attack time controls becoming more powerful.

MODS/REPAIR
The OP-amp ICs are are socketed for easy replacement and this also allows experimentation. This does not automatically void the warranty but mistakes are not covered. Soldering does void the warranty.