Vibra Chorus Owner`s Manual

Specifications
• Input impedance: greater than 1MOhm
• Output impedance: less than 10KOhm
• Controls: depth and rate
• Features: Stagger-tuned capacitors
with a unique ‘golden ratio’
• Pink LED: pulsates with modulation speed
for visual song tempo matching
• L.F.O.: 0.1-10Hz (smoothed triangle)
• Power requirements: 12VDC @ 1.2A
• Dimensions: width 6.8" depth 4.8" height 2"
• Weight: 2lb (on Earth); 0.3lbs (on Europa)
• Construction: solid die-cast aluminum box
• Finish: high-gloss Cadillac pink powder coat
Owner’s Manual
Warning: High D.C. voltages
of over 300 volts are present in
the circuit: disconnect power
before opening the unit. There
are no user serviceable parts
inside this pedal. Contact
Effectrode regarding warranty
or servicing.
Serial #
VC-1A
Copyright © 2009 Effectrode  Audiophile Pedals
33866 SE Eastgate Circle, Corvallis, OR 97333
www.effectrode.com
space
space
Introduction
The ‘Vibra Chorus’ pedal is specially designed to
reproduce haunting and ethereal chorus voicings
with hi-fidelity and a warm, natural tone. The
concept for this pedal was to take the archetypel
vibe sound and refine it to produce smoother and
more open chorusing. Only the barest minimum of
pitch de-tuning is introduced into the original signal
with absolutely no loss of treble for minimal tonal
coloration. This is a pedal with a unique musical
modulation characteristic that cannot be replicated
by other chorus, Uni-Vibe or vibrato pedals.
In use, the Vibra Chorus adds ambience and
dimension to slower playing and arpeggiated
picking making it very appropriate for blues and
ballads. At lower depth settings in creates a warm
subtle shimmer you can play through all night
without anyone being aware that any effect is being
used, other than the appreciating the outstanding
tone your guitar has. As the depth is increased the
pedal produces a liquid chorus which is somewhat
lighter in tone from a typical vibe and very guitar
approved!
Thank you for trusting Effectrode to be your effects
company. We wish you many years of musical
enjoyment from this hand-finished, all-tube pedal.
Phil Taylor – Technical Director
Tubes
To extend tube life, it is
recommended that the unit be
allowed to warm-up for at least
one minute after being switched
on. This is to allow the heater
filament in the tube to heat the
cathode, which is coated with a layer of barium and
strontium oxide. This oxide layer gets torn off the
cathode, a process known as cathode stripping, if the
cathode has not reached its correct operating
temperature. If operated well within their ratings,
good quality signal tubes can last 100,000 hours or
more: that’s well over 11 years of continuous use. If
you use your pedal for only 4 hours a day, they
should last over 25 years. (We can't warranty tubes
for this period, however experience shows that such
lifetimes are probable).
The 12AX7 tube in the Vibra Chorus can be swapped
with many 9-pin double triode tubes, including
12AT7, 12AU7 and 12AY7. These substitutions
typically yield lower gain and more headroom as well
as tonal differences depending on the tube type,
manufacturer, etc. Mil-Spec NOS are recommended,
if they can be obtained.
ce
space
In the scheme of things the Vibra Chorus sits
somewhere between Leslie/Fender Vibratone
rotating speaker systems and the first electronic
devices like the Uni-Vibe. So, in a way it's
something that was missed along the evolutionary
path of the chorusing effect. Its phase-shifting
circuitry is optimized to operate on the frequency
spectrum of electric guitar rather than the organ,
where the Uni-Vibe attempted to simulate a Leslie
rotating speaker system. This phase-delay
chorusing is distinctly different from the analog timedelay based chorus pedals that were widely used
during the 1980s and subjectively sounds more
pleasing natural to the ear.
Controls
Rate knob controls the chorus modulation rate. In
counter-clockwise positions the modulation is at it’s
slowest to create a dreamy, swirling and spacious
effect. This sound is more open and natural in
comparison to analog time-delay based (bucket
brigade delay) choruses - which can sometimes
sound a little artificial or contrived - and its
modulation characteristic has more in common with
Leslie rotating speaker. Rotating this knob further
clockwise produces a light, watery and bubbly
chorusing effect, whilst retaining clarity and
transparency.
Depth knob is used to adjust the depth of
modulation for more subtle effects. Unlike Vibe
effects, which tend to sound ‘darker’ on lower
intensity settings, the Vibra Chorus maintains a
much lighter tone on all depth settings. When used
sparingly (like tube driven spring reverb) it can add
a subtle shimmer and dimension to chord and
rhythm playing that will become integral to your
signature sound. You’ll wonder how you survived
without it!
Footswitch allows selection between effectified
(overdrive) and non-effectified (dry) signal. Silent
true bypass switching ensures there are no ‘pops’
or ‘thump’ when engaging the effect and that there
is absolutely no loss of tone from your guitar to your
amp when the effect is disengaged. Additionally,
the tube signal path in this pedal is built to
demanding audiophile specification to ensure hifidelity and signal integrity at all times - the benefit
that your guitar tone always remains pure and
intact.
Chorusing 101
Phase delay chorus - Early chorusing and vibrato
was achieved by means of a mechanical rotating
speaker assembly - acoustically adding doppler
phase-shifted signal to the original to produce phased
chorus and tremolo effects. Although bulky, these
systems are still much prized by blues players for
their unique sound. The effect can be heard on
Stevie Ray Vaughan’s ‘Cold Shot’ and ‘Tin Pan
Alley’, which was created using a Fender Vibratone.
Other users of the Vibratone include Pink Floyd
(‘Dark Side of the Moon’), Cream and Todd
Rundgren.
During the 1960s transistorized electronic phaseshifters (like the Uni-Vibe) were developed as a
compact and portable alternative. Although the UniVibe was not an accurate speaker simulator, it did
have its own unique character which players like Jimi
Hendrix and Robin Trower (‘Bridge of Sighs’) used to
great effect.
Time delay chorus - Time delay chorusing was first
achieved with studio tape machines. By the 1970s
miniaturization and integration of transistors made it
possible to manufacture analog electronic bucket
brigade delay line chips to do the same job, leading
to wide-spread manufacture of compact chorus and
flanger pedals. Digital delay hardware became
available a few years later, followed more recently by
digital modeling effects.