Progressions in digital amplification for guitar since the 1980s
This article is dedicated to digital technologies applied to effects and amplification for the electric guitar. We will start from the dawn and arrive to the most advanced solutions: digital amplifiers. We’ll deal with digital multi-effects, physical modelling, IR cabinets and practical suggestions
To get an overview on the electric guitar and its amplification development in the first half of the 20th century, please read the article about tube amps. Here we are going to talk about digital amplifiers.
Substantially, there are four kinds of guitar amplifiers:
In the first part of the article
we have concisely and distinctly dealt with:
In the first part we have talked
about information technology seeds between the ‘800 and the ‘900, and then
about the first electronic digital applications to the guitar world. In this second
part of the article about digital amplifiers we are going to deal with:
Physical modelling
By the end of the ’80s a new
technology appeared; it was already studied during the previous decade, though restrained
by insufficient performance of processors: we are talking about
physical modelling. Yamaha Corporation has the marketing
credit; the company had already collaborated with the Stanford University in
developing the
FM synthesis (frequency modulation synthesis, a renowned
example of which is the Yamaha DX7 synth). In 1989 Yamaha started a
collaboration with the same Institute in order to get and patent the
Digital Waveguide Synthesis.
In 1994 the first
physical modelling synth
appeared: the Yamaha VL1, the ancestor of a historic
change that was going to have a very big influence on guitar.
In the physical modelling synthesis a digital model of the sound
generating instrument is recreated, for example a plucked string (time depending);
the physical medium through which the sound is spreading (a constant), the kind
of instrument and the vibration with its possible restrictions, the string elasticity
and
gauge, player’s touch and lots of
other parameters are also recreated. The denser and more refined is the analysis,
the more compliant the simulation (a basic example of a clarinet partition is
shown in the drawing).
Compared to the past, the difference
is substantial: instead of trying to reproduce a sound by means of synthesis (from
Hammond organ [additive synthesis] to Moog synth [subtractive synthesis] to
samplers [sampling synthesis]), physical modelling itself produces a sound from
mathematical recreations of instruments, that, at this point, can be fantasy
products too, with their shapes and materials, propagation spaces and musical
rendition accents.
The gates of Hell – or Paradise, if
you prefer – were opened and the physical modelling simulation started targeting
every possible sound producing object. In the guitar field this means electric
and
acoustic guitars, every kind of amplifier, speaker, effect pedal, with special attention to vintage ones, that are finally available,
though as
virtual versions, for
musicians searching sought-after and peculiar sounds for their productions.
Among the brands that looked
after physical modelling for guitarists since the ‘90s let’s mention Roland (VG-8
guitar synth, 1995), Line 6 ( ,
1997) and the Yamaha Corp. (DG amps, 1998). Previous high end digital multi-effects
were outclassed in a short time, though refined solid state simulators, such as
the Tech21 Sansamp, remained. In the third millennium powerful and always
updated
digital machines continued to
be proposed until top products as Fractal Axe-FX preamplifiers arrived. In 2011
German firm Kemper introduced the
Profiler.
In addition to its resident amp models, this machine offers an innovative
approach; in fact, it allows the user to make its own traditional amps
profiles, including their speakers, the microphone and possible plugged in pedals. The obtained models can be shared online
among musicians or purchased from new
profiling
professionals.
Digital
power amps
A following version of the
Kemper Profiler was equipped with a
class
D power amp
. The circle was closed by a true complete digital amplifier with hundreds of amps and effects models and a
digital power amp.
Digital power amps, or class D power amps, are by now common
in many Hi-Fi,
Pro Audio and consumer devices. They receive the analogue signal,
convert it in an
impulse sequence tied
to the input signal amplitude and frequency (PWM), then amplify it at the
output with an efficiency unthinkable for analogue power amps.
Practical
use
When using a digital music machine we
always have to keep in mind that we are not using a tube amp or an analogue
pedal or a wood guitar, notwithstanding the finess and effectiveness of its
user interface. What seem to be potentiometers
are nearly always
encoders, converting
their given movement into digital data; parameter settings are “translated” following
our human habits. A good fruition of a digital machine actually needs a
friendly approach from both of its faces.
The first very successful
digital pedalboards, often provided with analog
sections, offered scarcely intelligible panels and unexpected or unpleasant
sounds. This often was because of guitar players’ poor knowledge of basic
settings such as volume and gain, layout of
effects
modules
in the signal chain, active
equalisation as opposed to passive tones, etc.
In the recording field, a personal
knowledge of most known and historically recorded amps and pedals is surely
advisable, especially in rock music. Following blog as this one and digital
recording forums certainly can be a great help in sharing information and other
items.
Let’s sum up some great advantages of
digital amplifiers:
Staying in the high quality machines
sector, the only drawback is represented by tradition and vintage keen guitar
players’ feeling that digital sound is “colder” and “less dynamic” than tube and
best solid state amps. Actually, if this comment can have some reason in live
use, in the studio and in a totally digital domain it seems quite insignificant
nowadays. Even the most famous rock players are abandoning real room recording of
amplifiers with miked cabinets.
The risk of sudden crashes on stage is also more and more
rare.
The
evolution continues
The rest is history these days. We
can count on integrated machines and physical modelling
simulation software that are capable of producing every kind of
guitar sounds, for recording and live playing as well, with tone and dynamic
qualities that were unpredictable at the beginning. Physical modelling is more
and more reaching
modelling amplifiers with a great quality/price ratio.
In the next years developments and
refinements in music information technology will make continuous important improvements.
This is the case of recent
IR
(acronym for Impulse Response) cabinets, that complete a cab model with
the algorithm of its response to a full range
impulse,
materials, volume, rooms, simulated microphones and their positions, etc, all
designed to give us a digital sound increasingly responding to the reference
physical reality.
Digital implementation resulting
from
psycho-acoustic studies, often
not stated, are integrated in consumer goods and in some cost effective guitar amplifiers
to get tone features of higher level models.
Technologies such as physical
modelling, IR cabs, Bluetooth for wireless connection and smartphone app are favouring
little, handy, versatile amps and other greatly useful products.
The old “hard and pure” analog
amplifier seems to be more and more far from the minds and habits of young musicians,
as well as from pros searching
convenient solutions for their business.
Digital evolution is a running train not to be missed in order to keep
pace with music!
References
Various, Plug In –
suppl. to Axe - Periodico per chitarristi no. 35
, 1999 Edizioni Palomino
F.Dadò, Kemper
Profiler test
on Axe - Periodico per
chitarristi no. 174,
2012 Edizioni Palomino
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