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The
Effects with brief description:
AMPLITUDE BASED EFFECTS
Volume control: Manual level control. Twist the knob, the sound
gets louder or softer.
Tremolo : Cyclical variation of volume by a low frequency
oscillator of some sort; parameters are waveform of the LFO, LFO
frequency, and depth of modulation; 'tremolo' is actually variation in
loudness, 'vibrato' is variation in pitch or frequency.
Auto tremolo: tremolo where the modulation frequency is varied by
some feature of the input signal, generally amplitude.
Panning/ping-pong: generalization of tremolo to more than one
channel; as one channel goes down in level, another goes up. With
non-square LFO waveforms, gives the effect of the sound source moving from
place to place in stereo or more channel setups.
Gating/repeat percussion: tremolo with 100% modulation of the
signal by a square wave. With exponentially decaying waveforms (guitar is
a good one), gives the effect of striking the same note again at
decreasing levels. Some Thomas Organ Vox amps have this as a built in
effect.
Compression: A compressor is basically a variable gain device,
where the amount of gain used depends on the level of the input. In this
case, the gain will be reduced when the signal level is high which makes
louder passages softer, reducing the dynamic range. This makes soft inputs louder, and loud ones softer, giving
a one-level kind of sound with lessened dymanics. This is effectively
volume control with the level determined by the negation of the averaged
envelope of the input level. Early compressors were often called "Sustain"
pedals.
Expansion: Makes loud sounds louder and soft ones softer.
Effectively volume control with the level determined by the averaged
envelope of the input level.
Compression and expansion can be complementary, as in >> com(pression/ex)panding
for noise reduction.
Asymmetric compression/peak compression: Only the peaks of the
input waveforms get compressed, not the overall level of the waveform
envelope. Effectively, there is no averaging of the envelope and the
instantaneous waveform level is compressed. This amounts to a much softer
form of clipping, and is part of the tube sound, since tube with a soft B+
supply are prone to this.
Noise gating: modulates the output off when the input level is
below a threshold. The modulation may be a square wave, or a variation of
expansion where the low level inputs are "expanded" down into silence,
which gives a less abrupt transition.
Attack delay: A variation of noise gating where the transition to
"on" from the "off" or no signal state is slowed. This gives an output
which perceptibly rises in level with each new note envelope, reminiscent
of a tape recording played backwards.
ADSR: Term borrowed from the synthesizer folks; stands for Attack
Decay Sustain Release, which is the most general way to describe a musical
envelope. It is possible to generate an artificial ADSR envelope for a
musical note to help fool the ear as to which instrument generated the
note.
Limiting: Like compression, but operates on signals over some
threshold only. Well suited to keep an input from going over some level,
but un-processed
below that level, as in getting signals on tape without overloading the
tape.
Auto swell: generally, a rise in level from some starting level to
a final level when keyed manually or electronically. Can effectively add
sustain to some notes and not others when keyed manually, or can add a
"swell" in volume over a run of notes, or can help with presetting the
level of a lead.
Presence: Many amplifiers have 'presence' knob as part of the tone
control system. This is simply a boost in the mid to high frequencies, say
from 2 to 6 kHz. This control is said to alter an instrument's sound on a
recording to give the impression that it is actually in the room with the
listener. It can also help an instrument stand out more in a mix.
FILTER/FREQUENCY RESPONSE EFFECTS
EQ/tone controls: Allow you to cut or boost the highs, lows, mids
etc. Tend to be broad-brush kinds of controls - all the "high's" get
raised or cut. Range is typically +/- 12 to 20 db boost/cut.
Treble/mid/bass boost: like an additional eq control, but tends to
be narrower in frequency range, and perhaps more boost range, no cut.
Cabinet simulation: A filter network designed to mimic the two- or
four-pole low frequency rolloff of a guitar speaker cabinet, usually to
get that "miked cabinet" sound into a PA without really miking a cabinet.
Resonator: a filter with a boost in frequency at a narrow range of
frequencies. This sounds like a wah pedal when the pedal is not being
moved.
Wah: A resonator that can have its center frequency moved up or
down in frequency by moving a pedal. The "wah" name comes from the way it
mimics the moving resonance of the human vocal tract in speech as the
sound "wah" is made.
Auto wah or "Envelope Follower": A wah filter where the center
frequency is determined by the loudness of the input signal, making a
moving resonance on every note. The Mutron-III was about the first
envelope effect. It was made in the mid 1970s, and is still thought to be
the best ever made by many players.
Tremolo-wah: Wah where the center frequency is moved back and forth
cyclically, as though the pedal was connected to a motor or some such.
This can generate effects similar to a rotating speaker or phasing.
"Vibrato": a cyclical variation in the basic frequency of the input
signal, similar to the effect of moving the whammy bar on a suitably
equipped guitar. True vibrato as an add on effect requires some kind of
time delay, and was hard to do until analog (and now digital) delays came
to be. The Uni-vibe,
(strictly speaking a phase shifter) designed in about 1967, had a vibrato
setting. However it is more famous fo it's "chorus" setting.
Phase shifting: This effect is a filter response generated by using
long phase delays and mixing with the original signal to cause a number of
deep notches and/or peaks in the overal filter response. This mimics the
larger number of notches and peaks caused by true time delayed flanging.
Most simple phase shifters or phasers do this by generating two notches,
although some pedals make four notches. Flangers may make many notches.
Phasers may
also incorporate feedback to sharpen up the effect of the notches.
TIME DELAY EFFECTS
Echo:
Reverb: Spring reverebs or Digital/Analog reverb
Flanging:
Chorus: the chorus effect can make a single instrument sound like
there are actually several instruments being
played.
Slapback: delay set to a short delay time.
Reverse echo/reverb
Delay: A delay takes an audio signal, and plays it back after the
delay time. The delay time can range from several milliseconds to several
seconds. The delay parameter simply controls the amount of delay
used. More specifically, it actually controls the minimum delay time that
is used. As the
delay becomes very small, the chorus will act as a flanger. Typical delay
times range between 20 and 30 ms. Sweep Depth/Width The sweep depth
controls how much the total delay time changes over time. It is usually
expressed in milliseconds, and the sum of the sweep depth and delay
parameters is the maximum delay used in processing the signal.
Distortion, Overdrive, and Fuzz
"Overdrive" is putting too large a signal into the input of an amp,
causing the signal to be distorted at the speaker. You were "overdriving"
the inputs. "Distortion" is getting a distorted sound from a little solid
state amp that is nonlinear. The terms are often used so interchangeably;
"overdrives" are a smoother, less harsh sound than the distortions.
Distortion pedals add a crunchy, gritty sound, whereas the overdrives add
more smoothness and not as much distorted crunch. "Fuzz" is a generic term
for a harder, harsher, and buzzier distortion than overdrive, and
sometimes considered harder and harsher than "distortion" by itself.
OTHER
Graphic Equalizer: a graphic equalizer is different than
the common tone controls. The bass and treble tone knobs on your stereo
boost or
attenuate only certain frequency bands while letting everything thing else
pass unaffected. A graphic equalizer uses a set of bandpass filters that
are designed to completely isolate certain frequency bands. In order to
have control over the total audio spectrum, the filters need to be
arranged in parallel. Each filter in the graphic equalizer has the same
input but only allow a small band of frequencies through.
Parametric Equalizer: A single parametric EQ allows you to
set the amount of boost or cut and also the center frequency and the
bandwidth. With experience, you can learn where to apply some boost to
help an instrument cut through the mix or achieve a fuller sound. For
feedback cancellation, a parametric EQ with a lot of cut (also called a
notch filter) can be positioned right at the frequency where the feedback
is occurring. To minimize the filter's effect on the rest of the sound,
you can use a small bandwidth. You might be able to control the feedback
with a graphic EQ as well, but if its bands are quite wide, you will be
cutting more of the sounds that you do want to be heard.
Octave division: Takes the fundamental frequency of an input
signal, divides it by two, and
creates an octave-lower, sometimes a two-octave lower signal, which are
usually mixed back with the original signal. This is most often done with
digital logic flipflops to divide the signal by two/four after squaring up
the
input to drive the flipflops. This provides outputs that are substantially
square waves, sounds like fuzz bass.
Some kind of filtering is usually provided to tame the sharp buzz of the
square waves. The simple dividers like this get very confused when fed
more
than one tone at once, so single note runs are all that is really
practical - unless you like confused effects.
Harmony generation:
Generation of other notes at musically-interesting intervals along with
your notes. The classic device to do this is the Eventide Harmonizer. It
is very
difficult to do this electronically so that the effect produces
musically-useful sounds consistently, hence Eventide's high price.
There is a new (1996) Boss pedal harmonizer now available which allows
selecting the key in which you are playing, and calculates and plays the
desired harmonic (3rd, 5th, etc). It is not cheap but several times
cheaper than an Eventide.
Phase lock tracking:
An electronic circuit called a "phase locked loop" can produce an output
signal that is exactly an integer multiple or small-numbers fractions of a
reference signal in frequency. You can generate: a signal that follows
your notes, perhaps lagging a little with a glide onto the note an octave
or two
above a third/fifth/seventh, etc. above or below your notes.
The outputs are usually square wave or filtered square wave, and sound
kind of synthesizer-y. Modern all-digital MIDI-fied effects do something
like
this in their computer processors, and may not be as limited in output
waveform.
Noise addition:
Noise (hiss, rumble, etc) is deliberately added to the input signal. If
this is done with restraint and matching the input signal envelope, it can
add a
breathing effect like the hiss of air in a flute.
Filtered low frequencies can add a growling quality.
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 Roland
Cube-30 Bass Combo 1X10
(30 Watts, 1x10)
Priced
around $300
SEE HEAD PANEL
Mfg Product Description
When it comes to compact bass amplifiers, the Roland Cube-30 Bass is in a
class all its own. Powerful and lightweight, it combines a 30W amplifier
with a 10" speaker and DSP modeling to crank out a range of popular bass
amp sounds. There's also onboard compression, Shape switch, 3-band EQ, and
digital effects.
Roland Cube-30 Bass Combo 1X10 Features:
30W of power
10" coaxial-design speaker
6 bass amp models
Shape switch
5 high-quality DSP effects: reverb, delay, chorus, flanger and T-Wah
3-band EQ
Compression
Auxiliary and footswitch inputs
Recording/headphones output
Roland Cube-30 Bass Combo 1X10 Specifications:
Rated Power Output 30W Nominal Input Level (1 kHz) INPUT: -20 dBu,
AUX IN: -10 dBu
Speaker 10" (25cm) + Tweeter (Coaxial type)
Controls
COMPRESSION knob,
SHAPE button,
COSM AMP TYPE knob (OCTAVE BASS, FLIP TOP,
B MAN, T.E, BASS 360, SESSION, CONCERT810),
GAIN knob,
VOLUME knob,
BASS
knob (EQUALIZER),
MIDDLE knob (EQUALIZER),
TREBLE knob (EQUALIZER),
EFX
(CHORUS, FLANGER, T-WAH) knob,
DELAY/REVERB, POWER switch n Indicators
COMPRESSION,
EFX,
POWER n Connectors INPUT jack (1/4" phone type),
AUX IN
jack
(stereo 1/4" phone type),
RECORDING OUT/HEADPHONE jack (stereo 1/4" phone
type),
FOOT SW jack (EFX on/off,
DELAY/REVERB on/off) (stereo 1/4" phone type) n
Power
Supply AC117V, 230V or 240V
Power Consumption 34W
Dimensions 15-1/4"W x 15"H x 9-1/4"D
Weight 20 lbs., 5 oz.
Accessories Owner's Manual
Options Footswitch FS-5U (BOSS)
Connection cable PCS-31
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ABOUT
GUITAR EFFECTS
discussion of basic guitar effects
in a combo amp head or as
independant of units
