REVIEW > COMPANY NAME DIGITAL ONLY REVIEW > CARL MARTIN
OPTICAL ENVELOPE FILTER
BY TYLER GREEN
Phasers, flangers, and wah-wahs are all great tools for adding funky, swirling,
and vowel-ish accents to your playing. But
few of these effects does the job quite as
musically as the envelope filter. The difference is the way in which an envelope —when
set correctly—will interact dynamically with
the guitarist’s hands. Carl Martin’s new envelope filter works brilliantly on this account.
It’s also a great pedal for players who like wah
textures but that don’t want to bother with a
wah on the pedalboard all the time.
to hear audio clips of the pedal at
When You Believe In Things
You Don’t Understand…
Let’s get down the important questions.
What do optics have to with a guitar pedal?
Well, you wouldn’t be the first to ask. Your
guitar’s sound wave can be broken down
into seven parts—amplitude, wavelength,
time, attack, decay, sustain, and release.
These last four criteria make up a wave’s
envelope. And once a sound has been
transcribed into an analog pulse you can
manipulate the wave envelope with an analog optical circuit.
How does this work? It’s simple;
there is a light and photovoltaic collector housed together in a light shielded
container. When the guitar is played, the
light flashes and the collector translates
the flash back into electronic signal.
When circuitry is added or depending
on how hard the player digs into the guitar or whether a booster is added before
the envelope, the envelope attack (how
quickly the light gets bright), sustain (how
long the light stays fully lit), decay (how
quickly the light dims) and release (how
long the light stays on) of the audio signal
is affected. Add this control parameter to
a filter and you get an optical envelope
filter. What sets this style of circuit apart
from a wah, which is a mechanical filter
dependent on foot sweeps, is that it is
electronic. This circuit type also differs
from phasers in that it does not rely on an
LFO to control the sweeps. It’s all in how
you set the parameters and play. In the
True Bypass Switching
case of the Carl Martin Optical Envelope
two optical circuits are involved with controlling the envelope.
Built into a sturdy powder-coated aluminum
case, the Carl Martin Optical Envelope has
a Hi Pass Tone control separate of the filters,
Drive knob (threshold control), Q knob
(bandwidth), Level knob (make up gain),
a foot switchable High Pass, Band Pass and
Low Pass filter control and buffered bypass
(rather than true bypass) footswitch. There
are three indicator lights for the bypasses
located above the filter switch and a red on/
off indicator switch located at the top of
the pedal. Besides the in/out jacks there is
a Boss-style power adaptor located at the
DR7 PREMIER GUITAR APRIL 2012