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 is 9 volt type: US "9
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 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) not exceeding
Three seperate distortion signals are
produced within this single device for a powerful means
of altering the distortion characteristic.They are
labelled D1, D2 and D3, in order of increasing distortion
increments. An essential feature is that the middle level
distortion generator (D2) is reversed in polarity,
allowing highly distorted "fuzz" type sounds to
be created using smoother sounding distortion generators
as building blocks. Three LED indicators on the front
panel show the progression of the level of distortion.
The MIX control is the
main determiner of the sound characteristic. Starting in
the center, you can go either left or right for two
versions of the same type of variation. On either side, a
"critical" region is found where the in-phase
components (D1+D3) cancel partially against the out of
phase one (D2). In other words, the sound whacks out.
This is marked "Z" and also "G" (see
below). The left side enphasizes the lower distortion D1
in volume but D3 still has more gain, which tends to
balance them into a mixed sound. The right side
emphasizes the higher distortion D3 and uses D1 to clean
the attack and balance out the sound. At "+D1",
"+D2" and "+D3" a corresponding one
of the distortions is dominant, but all settings are
still mixes and the +D1 and +D3 positions are pre-set
mixes of D1 and D3 (the lesser about one third the level
of the louder). Meanwhile the +D2 range controls a shift
between D1 and D3, the two in-phase signals each low
level but combining to still be audible.
The HI control also
contributes to the BLEND interactive to MIX. It cuts
highs of one of distortions D1 or D3 as indicated by the
"-D1" and "-D3" markings. The center
position is the start point and results minimum
alteration of the sound. At a MIX of +D1 or +D3, or
nearby, the highs are smoothed in two different ways by
turning HI to either side and treble is reduced somewhat
overall. At most other MIX positions overall treble tends
to be boosted by the action of HI. With the MIX control
in a critical position the action of HI becomes very
dramatic. After turning HI more to either side for a
particular MIX, try turning MIX a little more to its side
to further explore related sonic territory such high cuts
or a midrange notch.
The GAIN control adjusts
the amount of distortion and sensitivity. It is centered
on crossing the dynamic threshold where the three
distortions are most different and provide a
"vocal" emphasis. Lower settings shift this
emphasis into the attack of notes, and high settings go
"over" the dynamic threshold into either
complete turbulence or smoothness with a
"swell" effect on sustained notes. Also, the
far counter-clockwise setting (BCUT) cuts bass for
articulation beyond mere low gain (LO or above).
VOLUME is used to match
the volume to the bypassed sound and compensate for
changes in volume due to the other controls. It also
changes the tone somewhat in accordance with the internal
TONE trimpot (see below).
The BRAINS footswitch
enables the effect.
How It Works
A parallel mix of three distortions may be
produced simply by using a cascade (series)
|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
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 leaves 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 a clean signal mixing with a totally
distorted one, when not one of the individual
distortion signals are completely clean or
A wide range of sounds may be acheived by the
proper controls when the distortion elements
start out fairly smooth sounding by themselves.
Using three distortion levels further
complexifies the sound but also helps balance the
characteristics from being only extreme.
Subzombie's mix control also provides simple
in-phase mixing to be emphasized at the +D1 and
A further advantage of distortion mixing is that
the distortion characteristic can be caused to
vary with frequency by altering the frequency
response of one distortion source relative to the
others, producing a nonlinear filter.
This also has a conventional tone control
The D1 LED works differently than D2 and D3 because the
D1 distortion generator produces most of the gain and
increasing levels of distortion. The D2 and D3 stages
only contribute additional distortion and their LEDs only
indicate that addition. D3 illuminates with the least
input level and gain because the D3 distortion generator
has the most gain in combination. When the
distortion level increases to illuminate the D2 LED, then
D3 ceases to become much brighter, and likewise with D2
vs. D1. But, the D1 LED must be much less sensitive. When
the distortion increases enough to first light D1, the D1
LED lights at a level so low it is all but not visible,
but the D1 stage is is not limited by preceding
distortion stages and its LED continues to get brighter
with increasing distortion. At maximum gain and with a
high input level, the D1 LED becomes brighter than the D2
and D3 indicators.
GAIN also cuts bass at the
highest settings. This is not noticable in the way the
BCUT setting is because there is still a lot of bass gain
and the cut usually only prevents muddiness. At all
medium settings the pre-distortion frequency response is
wide bandwidth and uncontoured.
The critical regions of
the MIX control are marked "G" for a Gate point
where cancellation is strongest for clean signals, and
Zombie point "Z" where cancellation is
strongest when distortion is maximum. These points are
very close together on the left side but well spaced on
the D3 side. The control position markings are
approximate but closely spaced scale markings are
provided to aid repeat settings.
With increasing deflection
of the HI BLEND control, the stronger attenuation
progresses towards higher frequencies, with a full
low-pass response at maximum. Frequency also shifts
upward as +D1 and +D3 MIX positions are approached and
turning MIX and HI both far in the same direction causes
a rolloff of all three distortion signals. -D1 always
affects D3 somewhat and vice versa. All blending is
dynamically affected, varying with GAIN and input level.
The brightness of top
status indicator provides a crude indication of the
strength of the battery. The D2 and D3 indicators are NOT
affected by battery strength except when complete battery
failure results. It may be helpful to compare the
brightness of these indicators.
The internal TONE
trimpot and VOLUME
VOLUME also changes the tone somewhat in accordance with
the internal TONE trimpot. 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
with 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. TONE calibrates VOLUME depending on if a
balance with the bypassed sound is desired or if it
preferred to use the Subzombie for sounds that "cut
through" more, for example when driving into a dark
sounding or distorted amplifier.
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 a black circle with a screwdriver slot in
the center. Turning it clockwise increases the
action of the control and counter-clockwise minimizes it.
Its action is to increase the relative amount of bass by
reducing to volume of all other frequencies when the
VOLUME control is set to a middle setting. This also
improves the "taper" of the VOLUME control
response; setting the TONE control too far clockwise,
however, will cause a "flat spot" in the VOLUME
control taper where there is little change in volume
(except bass level) between the 9:00 and 1:00 positions.
Increased TONE settings cause the response shift to
extend higher in frequency but still level off, but the
full clockwise position will completely eliminate high
The input is designed
for 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. 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
Start with a clean amplifier setting, at least until you
get more familiar with the controls.
If you play a string while adjusting to "tune"
the mix, use enough gain, but then try turning down the
gain some for actual playing.
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.
To find a Zombie point, turn up the gain and play a
string loudly. Adjust the MIX for buzziest sound. Try
this with with HI centered, and then turn HI to 9:00 or
3:00. This will increase treble due to strongest
cancellation in the bass. Then turn MIX farther to the
side slightly to move the strongest cancellation to the
treble, reducing it. From this point, HI can be turned
farther to its side to cause a notch filter response.
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.
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.
The OP-amp ICs are are socketed for easy replacement and
this also allows experimentation. Replacement of the
first IC (nearer the input) also can allow higher power
supply voltage to a maximum of 21V, although improved
sound is unlikely. This does not automatically void the
warranty but mistakes are not covered. Soldering does
void the warranty. A possible mod is to increase the
output filtering capacitor. Easy method: a cap across the
VOLUME control's outer legs will parallel to the internal
.0022 uF cap. This reduces the low-pass filter's cutoff
frequency, but not consistently at all settings.
* High 666 K ohm input impedance when enabled.
True Bypass for no internal load when deselected.
* Output: 7 K ohm maximum impedance. Best when
driving high impedance loads, but also can drive
low impedance at reduced levels.
* Battery drain about 10 mA, highest when
* Bass response not limited to guitar range --
useful for bass (to 40 Hz or below). Bandwidth
slightly controlled at high gain settings.
One year. Does
not cover abuse. Please contact me before
returning for repair.