This month
begins a series on electronic keyboards ranging from
the1930's to the present
and how each keyboard's development was tied closely
to the technology of its time.
This month is second
in a series about classic keyboards. We feature a keyboard
that even if you never heard of it by name you have
heard it on hit songs by artists in many styles of music.
A sound that Ray Charles, ELO, Supertramp, Queen and
Three Dog Night to name only a few, have in common is
the Wurlitzer Electric Piano.
Until the Fifties keyboard
players and their band mates had to go where keyboards
were in order to play. A practice space or venue needed
to provide a piano or Hammond organ because these items
were too large to move. Keyboardists were also subject
to perform on these pianos and organs irregardless of
the condition they were in.
In 1954 the Wurlitzer
company started manufacturing the first models of its
electric piano, bringing not only an instrument with
a unique sound but a new era of portability giving keyboard
players an instrument they could carry with them and
the ability to personally maintain its condition.
The Wurlitzer Electric
Piano is a self contained instrument containing an amplifier
and speakers within its chassis. It wasn't very loud
because the early units had no way to output their signal,
but it could either be miked or an output could be derived
by modification to drive an external amplifier . Later
units featured headphone and also Auxiliary output jacks.
One of the beauties
of the Wurlitzer sound is that if the keys are played
hard and the internal amplifier is set loud, the amp
and speakers can be driven to a very musical sounding
distorted growl. The earliest Wurlitzer models contained
a tube amplifier which certainly enhanced its sound.
Later models in the sixties switched to solid state
amplifiers, but still distorted musically.
Other important
features of the Wurlitzer's sound was the inclusion
of a tremolo and a sustain pedal. The tremolo rate was
fixed, only its intensity was variable. The pedal enabled
sustain of the reeds by mechanically pushing the damper
felts off the reeds by a mechanical cable linkage connected
to the pedal.
But how does this piano produce
its sound? Wurlitzer developed a system of individual
metal reeds that each contained a blob of solder on
its tip. The lower pitch reeds were larger and the higher
ones smaller.The reeds by themselves were near each
desired pitch and the addition of solder to the tip
allowed a reed to be tuned to exact pitch by either
filing away solder to slightly raise its pitch or add
solder to lower the pitch. This was a sometimes maddening
method needed to attain the correct pitch. If you filed
off too much, then you had to add solder to the reed
and start filing again. The reeds were struck and made
to vibrate by the keys which were made of wood. These
keys, unlike the flimsy plastic keys on modern keyboards,
were one solid piece that extended from the playing
area back into the keyboard and when played the back
end pivoted up and struck the reed.It also simulated,
fairly well, a real piano action The mechanical tone
of the vibrating reed was converted to an electronic
signal that could be fed to the amplifier by placing
each reed in a 140 volt electric field. This was done
by placing the voltage on a metal plate (pickup) that
had cutouts surrounding each reed. The reeds were grounded
and formed a capacitor between themselves and the polarized
metal plate. The reason this is a capacitor can easily
be explained by stating the definition of a capacitor
which is the placing of a dielectric (non conducting
material that can store electrical charge)l between
two conductive plates.The size of the plates and the
specific dielectric material used determines the value
of capacitance measured in a unit called microfarads.
A capacitor is formed in the Wurlitzer pickup system
using the reed as one capacitor plate which is connected
to ground and the pickup becomes the other plate connected
to the 140 volt DC supply. Since air is a dielectric
material, the air between the pickup and reed is the
dielectric.. As the reed vibrates it moves up and down
in relation to the pickup and varies the value of the
capacitor. The capacitance changes at the frequency
the reed is vibrating at and creates a varying voltage
across a resistor that is hooked between the power supply
(140 volts) and the pickup. The varying voltage is then
amplified as an audio signal by the amplifier.
One warning to anyone considering
the purchase of a Wurlitzer. They can be tough to service.
The amplifier and speakers should be serviceable. Often
the amps only need an internal fuse replaced and some
sort of suitable speaker replacement can usually be
found for the oddball internal oval speakers. But the
true problems are in the servicing of the reeds. Due
to the type of steel they are made out of in order to
be flexible, they can become brittle and break especially
if you play hard.. There are replacements available
though if you search for them. The real service nightmare
is in the tuning. As I said above the reeds must be
filed to be tuned. The temptation to do this with them
still mounted in place is great. It saves a lot of time
and especially if there is a lot of tuning to do is
probably the way to go.The problem is the solder filings
hang around and over the next few weeks will manage
to work themselves between some of the reeds and the
pickup. Since the pickup is at 140 volts and the reed
is at ground, this will short the 140 volts to ground
intermittently as the reed vibrates causing loud crackling
noises through the speakers. Not a lot of fun at a gig.
I've owned and
worked on many of these pianos. In college I had a model
112 containing a tube amp. It enabled me to practice
in my parents Manhattan apartment without disturbing
them or the neighbors (they were not so lucky with my
guitar playing though which was very loud.) I have serviced
many a model 200A,the most well known model of the series,
one of which someone had pulled out of a dumpster and
I was able to restore it to its full beautiful sound.
Steve
Weiss is the owner and main technician of Steve Weiss
Electronics Inc. He is experienced in the repair
of analog and digital musical equipment. This includes
everything from Vintage Tube Amps and Pro Audio equipment
to Digital Keyboards There is also a guitar repair
shop staffed by some of the areas top guitar repair
techs. He is authorized for warranty work on most
major brands. Steve Weiss Electronics is located
inside of Sam Ash Music at 5460 West Sample Road
Margate, FL 33073 954-975-3390 Ext 272. Steve has
also spent 25 years on the road as a performing guitarist
and is the designer of Primal Guitar amps that can
be seen at Primal
Audio.com Steve can also be reached at stevew@metromusicmayhem.com |
|
|
