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The increase in popularity
of acoustic music in the last decade surely must be attributed
to the advances in amplification technology. Acoustics instruments
with pickups are seen with increasing regularity in high profile
venue such as MTV Unplugged. It is fashionable to be Unplugged
nearly all performers in the popular music field are plugging
in their acoustic instruments.
The change in acoustic amplification
started slowly in 1960’s with the Gibson C-1E bridge-piezoequipped
Classical Guitar as played by Charlie Byrd. In 1971 Ovation
introduced the Ovation acoustic-electric which received hugh
exposure through Glen Campbell's playing on his weekly TV
show. This began a virtual explosion of pickup designs by
such as L.R.Baggs, Emg, Barcus-Berry, Fishman and Highlander.
In the last decade, the acceptance
and options for amplifying acoustic instruments have expanded
dramatically. The options for transmitting the instrument
sound to the amplification source now include:
- Piezo Pickups
Under-saddle pickups read string vibration transmitted through
the instruments bridge. Piezo-pickup design require two
elements. Firstly the sensing device which records what
is happening in the bridge area and secondly a buffer pre-amp
which thanks to advances in technology are now small enough
to mount onboard a guitar and remain almost invisible. Highlander,
L.R. Baggs and Fishman are leaders in this technology. Another
advantage of this technology is the availability of MIDI
interface.
- Vibration Sensors
This pickup design responds to movement of the top. And
although this design does not allow for high sound pressure
levels as does the under saddle pickup it does offer rewards
in the area of tone. Trance Audio produce excellent high
end pickups in this field.
- Magnetic Pickups
A new generation have emerged which feature a wider frequency
response as compared to the traditional electric guitar
pickup. The industry standard for frequency response has
been the Sunrise. Rare Earth from Fishman and the ACS from
EMG also feature in this area.
- Dual Source Systems
Virtually all the big names in the pickup business, including
Baggs, EMF, Fishman, and Highlander, offer such systems.
One of the latest advances in acoustic instrument amplification
uses a piezo under-saddle pickup and a mic, and blends the
signals with either an on-board preamp or a stereo cable
to an external mixing source. The result is a more open
sound that includes more "air." This system is more susceptible
to feedback because of the presence of the inbuilt microphone.
Having said that, the problem is not as great for solo playing
which does not generate high on stage noise.
- Condenser Microphones.
With the introduction of a number of reasonably price condenser
microphones this is a very viable option for the traditional
concert gig. High sound pressure levels can not be achieved
but feedback is not a problem for solo or small ensemble
performances and it does offer the best alternative for
sit down audiences.
Audiotehnica AE5400
Once the initial sound source
has been captured it remains to project this sound at an optimum
volume to the audience. The alternatives for acoustic musicians
are as follows:
- Acoustic Amplifier
Acoustic amp design, led by the Trace Elliot company, targeted
the specific problems of amplifying the acoustic guitar.
They introduced advances to the typical electric guitar
amp design to produce a product that could accommodate the
intricacies of the natural acoustic sound. They included:
- Much wider frequency response. Dual channels, one
is usually designed with a high input impedance for
a direct piezo input, while the other may be used for
a microphone or magnetic pickup.
- Redesigned EQ Section tailored for acoustic guitar
tone, usually including a notch filter and phase switches
to help reduce feedback.
- Inbuilt effects and effect loops Reverb or delay can
be used to fatten your sound. One of their most significant
features is that these amps can also serve as mini PA
systems, handling a vocal mic in addition to the guitar.
Modular Stage System
With the advent of low cost components by manufacturers
such as Behringer it is an option consider a portable stage
system to cover your amplification needs.
A setup consisting of a small mixer hooked into a pair of
powered speakers allows considerable flexibility for the performer.
Benefits include:
- Wider dispersion of sound. The Acoustic Amp disperses
sound from one point in the room and often does not
provide adequate coverage to all points in the room.
- More Input alternatives. Additional instruments may
be plugged in for ensemble performances. Stage microphones
can be utilized for both on stage patter and condenser
microphone for additional acoustic amplification.
- Wider frequency response. A dedicated mixing board
will give advantages over the input section of an acoustic
stage amp. Features such as effect loops that enable
the patching of high quality audio processors and a
more comprehensive EQ section offer greater freedom
of choice to the performer.
In summary under-saddle technology is hard to beat as far as
complete frequency response and immunity from feedback go, although
there is still that "wood and air" sound missing. Digital signal-processing
advances will in the near future solve this problem.
Under bridge design appears
to have become the most accepted method of producing acoustic
guitar at reasonable levels of sound with remaining sticking
point that of tone. This I believe will be solved in the near
future by virtual acoustic solutions like the directions taken
by the Line
6 Pod and COSM technology used by Roland.
Instruments by Takamine,
Ovation, Yamaha, and Godin using this design offer the musician
of today many reasonable price alternatives to explore.
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