- Wall
Wart
- A colloquialism
used to describe the type of external power supply where the transformer,
and sometimes other components, are located in a box that houses the connector
that plugs into the electrical outlet. These types of power supplies have
seen wide spread use in the last ten or so years due to their low cost, ease
of manufacture, versatility, and sonic improvements; equipment with external
power supplies are usually quieter (all other things being equal) than equipment
with internal supplies. A company who builds many devices which do not require
a lot of power to operate may be able to use one generic power supply for
each of them, which greatly reduces the cost of the development for each device.
Since only the device which connects to a wall outlet must be UL approved
(see WFTD archive UL), each new device
that a manufacturer develops does not have to go through the time and expense
of getting UL approval.
Many consumers
do not like these types of power supplies, however, because the size and
weight of the box that plugs into the electrical outlet can be cumbersome.
They are large enough that one of these supplies usually will cover two
or more outlets on a typical power strip, and heavy enough that when plugged
in to a wall (or vertically positioned power strip) they can fall out very
easily. Many manufacturers are now aware of the public's disdain for wall
warts and have been making more of an effort to include the power supply
inside of their equipment, which allows a standard power cord to be used.
If cost or other factors do not allow for internal power supplies manufacturers
have been leaning towards "lump-in-the-line" supplies, where the transformer
box is half way between the electrical plug and the connector to the equipment.
This solves most of the problems of external power supplies while retaining
most of the advantages of them.
- Watt
- A metric unit
of power defined as one Joule per second. The Joule is a unit of energy, so
power equates to the rate of energy transfer, or the rate of doing work. Named
after James Watt, the developer of the practical steam engine, the
watt has become a common term in audio as used to describe the power handling
capabilities and/or requirements of speakers, and the power delivery capabilities
of amplifiers. Milliwatts (1/1000 of a watt) are often used to describe energy
usage in low power electrical circuits.
- Wave
File
- The format for
computer system audio files defined by Microsoft for use with Windows. Wave
files are indicated by a .wav suffix in the file name and are often spelled
wav (instead of wave) in writing. The .wav file format is an expandable format
which supports multiple data formats and compression schemes. Wav files are
pretty much the de facto standard for serious audio work on the PC Windows
platform.
- Waveform
- The waveform
of a signal is a graph of its instantaneous voltages
versus time. In audio, for example, we are always dealing with periodic waveforms
that make up what we hear. These periodic waveforms can be plotted on a graph
and will show up as some type of squiggly (how's that for a word?) line. From
left to right is time (usually a very short slice of time) and from top to
bottom is the amplitude of the sound (or relative voltage) at those instants
in time. The familiar sine wave is an example of this.
Waveforms,
or Waves (a Wave File, for example) are
also the names sometimes given to samples or snippets of sound that are
used in various electronic sound generating or playing instruments. The
usage of the word comes from the definition above and has become commonplace
in the modern day era of audio production where one is often looking at
waveforms on a computer screen while editing sounds.
- Wavelength
- Denoted by the
Greek lower-case lambda symbol (l), the distance between one peak or crest
of a sine wave and the next corresponding peak or crest. The wavelength of
any frequency may be found by dividing the speed of sound (approximately 1100
feet (or 34 meters) per second at sea level) by the frequency. Thus the wavelength
of a 60hz sine wave would be approximately 18.3 feet. Knowing wavelengths
of sounds is very important when designing or working with acoustic spaces
such as studios, control rooms, and speaker enclosures.
- Wavetable
Synthesis
- A method of
sound synthesis in which waveforms are generated
by loading their characteristics from a special set of parameters stored in
a lookup table in computer memory. Advanced wavetable synthesizers are able
to crossfade between different waveforms
while notes are sounding, which can produce very complex sounds. The resulting
complex waveforms are often further modified by other filtering
techniques and envelope generators.
- Weighting
- Often times
when laboratory measurements are taken of audio gear, the literal, "true"
figures obtained do not reflect the anomalies introduced by human perception.
In these cases, the specs obtained may be mathematically modified, or "weighted"
to take into account the way our ears work. A good example is "A-weighting",
a curve applied to sound pressure levels to more accurately reflect our loudness
perception. Other types of weighting compensate for the ear's frequency response,
etc.
- White
Book
- The spec for
Video CD, the White Book (not to be confused with the White album)
was developed by JVC, Matsushita, Philips, and Sony.
Video CD has never taken off as a major CD format.
- White
Noise
- Random noise
with equal energy per frequency is called white noise. It tends to sound very
bright and "hissy" due to our ears frequency response curve. (Each ascending
octave contains twice as many frequencies as the next lower one, so there
is a significant "build up" of energy in the higher octaves.)
- Wild
Time Code
- A phrase used
to describe time code that is not resolved
to any known reference. It is time code that is just running (or recorded)
at whatever rate the time code generator happens to be putting out. This often
becomes an issue when someone stripes time
code to a video tape without resolving it to the frame
rate of the video. The time code will drift relative to video such that
it can become impossible to later sync audio material recorded to the working
video dub (and its wild time code) to the master video tape.
- Word
Clock
- Digital data
is comprised of "bits" (see WFTD "Bit")
which are organized into "words" representing sample values. Word clock is
a synchronizing signal based on the sample rate or the speed with which sample
words are sent over a digital connection. Word clock is used by the receiving
digital device to decipher where in the data stream each sample word ends,
as well as whether the word belongs to the right or left channel (in a stereo
signal).
When transmitting
digital audio signals from one piece of gear to another, it is therefore
important that their clocks be synchronized (i.e. the receiving device is
made to "slave" its clock to the transmitting device's internal clock, or
the whole system is locked to an external house sync signal or master clock),
otherwise the sample words in the data stream will not be "lined up" correctly
in the receiving device, possibly causing clicks, pops and other audio degradations.
- WORM
- Another acronym.
This one stands for Write Once, Read Many, and
is a short name for CD recordable drives and media. The name is fairly self
explanatory, you may write only once to this type of media, but read from
it many, many times. More recently the abbreviation CD-R (CD Recordable) has
been used in place of the WORM acronym, presumably to make the technology
more easily understood, and thus marketable, to the masses.
- Wow
- Wow is a relatively
slow variation in the frequency of reproduced sound caused by slow speed variations
in records, tape recorders, etc. Pitch fluctuations of one or two per second
are classified as wow, while faster variations are called flutter. In spec
sheets wow is usually rated, along with flutter, as a percentage where the
percentage is the percent of pitch deviation produced by these two phenomenon
in the machine. In practice we have found wow and flutter specs to be more
of a ballpark or relative measure. Machines can behave very differently depending
upon the type of tape used or even environmental factors which can affect
tape consistency. This is especially true with cassette type tapes where the
tape shell's interaction with the tape is a huge variable. Wow and flutter
are almost never an issue in digital recorders because tape speed has no direct
bearing on the pitch of the audio playback or recording.
- Wrap
- Possibly a radio
station specializing in rap music. In the domain of music equipment, specifically
tape recorders, wrap is the angle made by the tape as it approaches and leaves
the tape head. Wrap is actually a measure of the distance along the face of
the head where tape makes contact. This distance has an effect on the low
frequency response of the playback head.