This is the name of a new site about «decent» audio
constructions for everyone.
Relative themes: Power supplies, Amplifiers, Loudspeakers.
There are many recipes for excellent sound quality at no cost at
all.
The new approach is to make this site our interactive
audio community.
Here you can publish
your ideas and constructions.
We must think clever to beat the expense of a High End construction.
I think that this is the way to have benefits for all of us.
Please send E-mail: agkapa@yahoo.gr to tell me what you prefer the shape (structure of our site)
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Some info for Speakers :
Acoustic
suspension
A sealed or closed box speaker enclosure.
Alignment
A class of enclosure parameters that provides
optimum performance for a woofer with a given value of Q.
Alpha
In sealed enclosure designs, the ratio of Vas to Vb, where Vb is
the volume of the box you will build. See sealed enclosure.
Alternating
Current (AC)
An electrical current that periodically changes in magnitude and
direction.
Ampere
(A)
The unit of measurement for electrical current in coulombs per
second. There is one ampere in a circuit that has one ohm resistance
when one volt is applied to the circuit. See Ohms Law.
Amplifier
An electrical circuit designed to increase the current, voltage,
or power of an applied signal.
Aperiodic
Enclosure
An otherwise sealed enclosure design, but with a vent that is
stuffed with damping material, which flattens out the impedance
curve of
the design. The area of this resistive vent should be about 10
sq. in. per cubic ft. of enclosure volume. This design might take
some experimentation with the vent stuffing, testing the impedance
curve several times with different amounts of damping material
until the flattest impedance curve is found. The aperiodic resistive
vent damps the driver in much the same way as fully stuffing a
sealed enclosure with damping material (100% fill). In this way,
an optimum design may be made up to 20% (or more) smaller due to
the extra damping of the resistive vent. Enthusiasts of this design
often compare the performance with transmission line enclosures,
advocating that the design avoids the "ringing" effects of ported
enclosures while alleviating the "pressure effect" of the sealed
box. Dynaudio sells a DIY insertable resistive
vent called the Variovent.
Attenuation
The reduction, typically by some controlled
amount, of an electrical signal.
Audio
frequency
The acoustic spectrum of human hearing, generally regarded to be
between 20 Hz and 20 kHz.
Baffle
A board or other plane surface used to mount a loudspeaker.
Bandwidth
The range of frequencies covered by a driver
or a network (crossover).
Band-pass
Enclosure
See dual reflex bandpass and single reflex
bandpass.
Band-pass
filter
An electric circuit designed to pass only middle
frequencies. See also High-pass and Low-pass filters.
Basket
The metal frame of a speaker.
Bass
Blockers
First order high pass crossovers (non-polarized
capacitors), generally used on midbass or dash speakers to keep
them from trying to reproduce deep bass.
Bass
(lows)
The low end of the audio frequency spectrum, from approximately
20 Hz up to 400 Hz or so.
Bass
Reflex
A ported enclosure.
Beaming
The tendency of a loudspeaker to concentrate the sound in a narrow
path instead of spreading it.
Boomy
The smearing of transients that makes bass
reproduction sound muddled, usually because of improperly designed
sealed (to small), ported (to small or tuned improperly), and bandpass
enclosures, although the latter are sometimes designed this way
on purpose by car audio manufacturers or install shops to be loud.
Bridging
Combining both left and right stereo channels
on an automotive amplifier into one higher powered mono channel.
When an amplifier is bridged, the impedance that the amplifier
actually "sees" is calculated based upon the output of both stereo
channels. Here is a simple formula to help define this:
Bridged Mono Impedance = (Y / X)/2
Y = impedance of driver(s) (both drivers should be identical)
X = # of drivers in circuit
So, hooking up one 4 ohm sub bridged mono would be equal to hooking
up two 2 ohm subs in stereo, one to each channel.
Cabin
gain
The low frequency boost normally obtained
inside a vehicle interior when subs are properly mounted.
Capacitor
A device made up of two metallic plates separated
by a dielectric (insulating material). Used to store electrical
energy in the electrostatic field between the plates. It produces
an impedance to an ac current. In automotive applications, special "Power
Line Caps" can be connected inline to the amplifier to aid the
alternator in supplying current demands of amps. Non-polarized
capacitors can be used as first order passive high pass crossovers,
or as components in more complex high pass, bandpass and lowpass
crossovers. See power line caps.
Center
Channel
In home theater, sound decoded from the stereo
signal sent to a speaker mounted in front of the listener, specially
designed to enhance voices and sound effects from a movie soundtrack.
Used in car audio to help offset skewed stereo imaging due to seating
positions in the automotive environment.
Channel
The path an audio signal travels through a circuit during playback.
At least 2 channels are required for stereo sound.
Circuit
A complete path that allows electrical current from one terminal
of a voltage source to the other terminal.
Clipping
A distortion caused by cutting off the peaks of audio signals.
Clipping usually occurs in the amplifier when it's input signal
is too high or when the volume control is turned to high.
Cms
Mechanical suspension compliance of a driver,
consisting of the spider and surround.
Coaxial
Driver
A speaker composed of two individual voice
coils and cones; used for reproduction of sounds in two segments
of the sound spectrum. See also triaxial driver.
Coulomb
6.25 (10)^18 electrons
per second.
Coloration
Any change in the character of sound that
reduces naturalness, such as an overemphasis of certain tones.
Compliance
The relative stiffness of a speaker suspension,
specified as Vas.
Cone
The cone-shaped diaphragm of a speaker attached
to the voice coil which produces pulsation's of air that the ear
detects as sound.
Crossover
Frequency
The frequency at which a driver's response
is down -3dB. See Roll-off.
Crossover
Network (Filter)
An electric circuit or network that splits
the audio frequencies into different bands for application to individual
speakers. See Electronic and Passive Crossover.
Current
(I)
The flow of electrical charge measured in
amperes.
Damping
The reduction of movement of a speaker cone,
due either to the electromechanical characteristics of the speaker
driver and suspension, the effects of frictional losses inside
a speaker enclosure, and/or by electrical means.
Damping
Material
Any material added to the interior of a speaker
enclosure to absorb sound and reduce out-of-phase reflection to
the driver diaphragm (cone). Usually acoustic fiberglass, polyester
batting, or Polyfill is used in speaker enclosures.
Decibel
(dB)
Alogarithmic scale used to denote a change
in the relative strength of an electric signal or acoustic wave.
It is a standard unit for expressing the ratio between power and
power level. An increase of +3 dB is a doubling of electrical (or
signal) power; an increase of +10 dB is a doubling of perceived
loudness. The decibel is not an absolute measurement, but indicates
the relationship or ratio between two signal levels.
Diaphragm
The part of a dynamic loudspeaker attached to the voice coil that
moves and produces the sound. It usually has the shape of a
cone or dome.
Direct
Current (DC)
Current in only one direction.
Diffraction
A change in the direction of a wave front
that is caused by the wave moving past an obstacle.
Dispersion
The spreading of sound waves as it leaves a speaker.
Distortion
Any undesirable change or error in the reproduction
of sound that alters the original signal.
Dome
Tweeter
A high frequency speaker with a dome-shaped diaphragm.
Double
(Dual) Voice Coil (DVC)
A voice coil with two windings, generally subwoofers. Each voice
coil can be connected to a stereo channel, or both voice coils
can be wired in parallel or series to a single mono channel.
Driver
A loudspeaker unit, consisting of the electromagnetic
components of a speaker, typically a magnet and voice coil.
Driver
Parameters
The physical properties of a driver that
determine it's electrical and acoustical behavior. The minimum
parameters used in determining speaker enclosures are Fs, Qts,
and Vas. See Thiele/Small Parameters.
Dual
Reflex Bandpass Enclosure
Sometimes called a 6th order bandpass. In
these designs, Vr is ported as well as Vf, so that there are 2
resonant frequencies. Vf and Vr are tuned about an octave apart,
providing the driver with excellent damping at resonance, even
further reducing distortion. This design is even more efficient
than a single reflex bandpass, but with a compromise. The system
has the same high frequency roll-off of -12 dB/octave, but low
frequency cut-off is at -24 dB/octave (just like a regular ported
enclosure). Power handling is excellent within it's frequency bandwidth,
but these designs are similar to ported in that they are subject
to low frequency noise upsetting the driver(s) below F3. Transient
response is also rather poor, but these enclosures can be made
to play very loud. One of the most difficult enclosures to build
and tune.
Dynamic
range
The range of sound intensity a system can reproduce without compressing
or distorting the signal.
EBP
Efficiency Bandwidth Product. A rating that
helps a builder determine whether a driver is suitable for a sealed
or ported enclosure. EBP of less than 50 indicates the driver should
be used in a sealed, 50 - 90 indicates flexible design options,
over 90 indicates best for a ported enclosure.
EBP = Fs / Qes
Efficiency
rating
The loudspeaker parameter that shows the level of sound output
when measured at a prescribed distance with a standard level of
electrical energy fed into the speaker. Note, however, that a driver
with a high efficiency rating needs a larger box to play a lower
frequency than a driver with a lower efficiency rating. This means
that a low efficiency driver in a small box will actually have
higher sub bass SPL's than a high efficiency driver in a similar
small box!
Electronic
Crossover
Uses active circuitry to send signals to
appropriate drivers. More efficient than passive crossovers.
Enclosure
The box that contains the driver(s).
Equalizer
Electronic device used to boost or attenuate
certain frequencies.
F3
The roll-off frequency at which the driver's
response is down -3dB from the level of it's midband response,
sometimes called the cutoff frequency.
Fb
The tuned frequency of a ported box.
Fc
or Fcb
The system resonance frequency of a driver
in a sealed box.
Fs
The frequency of resonance for a driver in
free air.
Farad
The basic unit of capacitance. A capacitor
has a value of one farad when it can store one coulomb of charge
with one volt across it.
Filter
Any electrical circuit or mechanical device that removes or attenuates
energy at certain frequencies. See Crossover Network.
Flat
Response
The faithful reproduction of an audio signal;
specifically, the variations in output level of less than 1 dB
above or below a median level over the audio spectrum.
Free
Air Resonance
The natural resonant frequency of a driver
when operating outside an enclosure.
Frequency
The number of waves (or cycles) arriving
at or passing a point in one second, expressed in hertz (Hz).
Frequency
Response
The frequency range to which a system, or any part of it, can respond.
Unless a limit of variation in intensity is stated, this specification
is meaningless. i.e., you see a subwoofer in a ported enclosure
with a rated response of 35 - 300 Hz. Means nothing. It could very
well be that it is 35 - 300 Hz (-24 dB), which means the low frequency
roll-off actually begins at around 70 Hz. It needs to read something
like this: 35 - 300 Hz (- 3 dB), which gives 35 Hz as the actual
roll off frequency.
Fundamental
Tone
The tone produced by the lowest frequency component of an audio signal.
Full-range
A speaker designed to reproduce all or most
of the sound spectrum.
Golden
Ratio
The ratio of the depth, width, and height of a speaker enclosure, based
on the Greek Golden Rectangle. Usually recommended for home speakers,
difficult to use in car audio applications. The Ratio: W = 1.0,
Depth = 0.618W, Height = 1.618W.
Ground
Refers to a point of (usually) zero voltage, and can pertain to
a power circuit or a signal circuit. In car audio, the single
most important factor to avoid unwanted noise is finding and
setting a good ground.
Harmonic
The multiple frequencies of a given sound, created by the interaction
of signal waveforms.
Harmonic
Distortion
Harmonics artificially added by an electrical
circuit or speaker, and are generally undesirable. It is expressed
as a percentage of the original signal. See THD.
Head
Unit
The in dash control center of a car audio system, usually consisting of
an internal low powered amp, AM/FM receiver, and either a tape
or CD player (or both).
Hertz
(Hz)
A measurement of the frequency of sound vibration.
One hertz is equal to one cycle per second. The hertz is named
for H.R. Hertz, a German physicist.
High-pass
Filter
An electric circuit that passes high frequencies
but blocks low ones. See Band-pass and Low-pass filters.
Hiss
Audio noise that sounds like air escaping from a tire.
Home
Theater
An audio system designed to reproduce the
theater sound experience while viewing movies in the home. Minimally
consisting of a Dolby Pro Logic® surround sound receiver, left
and right front speakers, a center channel speaker, and at least
(1) surround sound speaker. These plus optional subwoofer(s), surround
speaker(s), and digital formats such as Dolby Digital® can
enhance the viewing experience by drastically improving the sound
quality of movie soundtracks.
Hum
Audio noise that has a steady low frequency pitch.
Imaging
See Soundstage.
Impedance
The opposition of a circuit or speaker to ac current; the combined effect
of a speaker's resistance, inductance, and capacitance that opposes
the current fed to it. It is measured in ohms and varies with the
frequency of the signal.
Inductance
(L)
The capability of a coil to store energy in a magnetic field surrounding
it. It produces an impedance to an ac current. Inductors are commonly
used in audio as low pass crossovers. See Le.
Infinite
Baffle
A flat surface that completely isolates the
back wave of a driver from the front without a standard enclosure.
Infrasonic
(Subsonic) Filter
A filter designed to remove extremely low
frequency (25Hz or lower) noise from the audio signal. Useful for
Ported box designs.
Input
The current fed into a loudspeaker.
Isobarik
Enclosure
Enclosure where one woofer is buried in the enclosure and a second
is mounted up against the first and wired in reverse polarity (there
are other variations for Isobarik designs, but this one is the
best). This allows the effective Vas of both drivers working in
this push-pull configuration to be half that of a single identical
driver mounted normally. Very small enclosures may be constructed
as a result, with increased power handling. Any variation of a
normal enclosure can be made Isobarik - so you could conceivably
have an Isobarik dual reflex bandpass, ect. (good luck tuning it,
though). Less efficient than other designs, but the push pull configuration
greatly reduces second order harmonic distortion. Originally, a
variation of this design was patented by Ivan Tiefenbrun, who produces
various audiophile components in Scotland under the name of Linn Products. The name Isobarik comes from
a term that means "constant pressure". See push-pull.
Kilohertz
(kHz)
One thousand hertz.
Le
The inductance of a driver's voice coil, typically measured at 1 kHz in
millihenries (mH).
Low-Pass
Filter
An electric circuit designed to pass only low frequencies. See
Band-pass and High-pass filters.
Lobing
The tendency of a speaker system that consists of more than one driver
to produce a lobed frequency response in space with in-phase reinforcement
(lobes) from the various drivers occurring at some elevations and
out-of-phase opposition (nulls) at points between the lobes.
Maximum
power rating
A value which means almost nothing, but is
used nonetheless by manufacturers to entice the unsuspecting into
purchasing their product based solely on the big number. Technically,
it is the maximum wattage that an audio component can deliver/handle
as a brief burst during a musical peak. Most reputable manufacturers
will provide both an RMS and Max power rating. Typically, the given
value for the maximum power rating is twice to three times that
of RMS. Automotive head units are a good example of this shady
technique, as all the ones I have ever seen use this rating for
the built in amplifier output. Use RMS for determining real world
equipment capabilities. See WLS.
Microfarads
(mF)
A measurement of capacitance.
Midbass
Mid level bass, usually frequencies just
above the sub-bass range, from around 100 - 400 Hz or so.
Midrange
(mids)
The frequency range above bass but below
treble that carries most of the identifying tones of music or speech.
It is usually from 300 - 400 Hz to 3kHz or so.
Millihenries
(mH)
A measurement of inductance.
Mms
The moving mass of a driver assembly.
Mono
Monophonic sound. A method for reproducing sound where the signals
from all directions or sources are blended into a single channel.
MOSFET
Metal Oxide Semiconductor Field Effect Transistors. Used in most
modern, quality car audio amplifiers in the power supply (and
sometimes in the output stage). MOSFET's run cooler than normal
bipolar transistors, and have a faster switching speed.
Noise
Any undesirable sound reproduced in an audio
system.
Octave
A range of tones where the highest tone occurs
at twice the frequency of the lowest tone.
Ohm
A unit of electrical resistance or impedance.
Ohm's
Law
A basic law of electric circuits. It states
that the current [I] in amperes in a circuit is equal to the voltage
[E] in volts divided by the resistance [R] in ohms; thus, I = E/R.
Out
of Phase
When your speakers are mounted in reverse
polarity, i.e., one speaker is wired +/+ and -/- from the amp and
the other is wired +/- and -/+. Bass response will be very thin
due to cancellation.
Output
The sound level produced by a loudspeaker.
Passive
Crossover
Uses inductors (coils) and capacitors to
direct proper frequencies to appropriate drivers. These crossover
systems can be simple (First Order = 1 component @ -6 dB/octave
slope) to complex (Fourth Order = 4 components @ -24 dB/octave
slope).
Passive
Radiator
A device that looks just like an ordinary driver, except it has
no magnet or voice coil. A radiator is usually a highly compliant
device, with a similar cone material and surround found on regular
active drivers. The radiator must usually be at least as large
(or larger) than the driver it is aligned with. The passive radiator
is tuned to Fb and used in place of a port, providing bass reinforcement
for the driver in a similar fashion as any regular ported box.
A clear advantage of the radiator is the absence of port noise,
and some audiophiles claim the radiator provides a better sounding
bass than a ported enclosure. Disadvantages include difficulty
in tuning, and the extra required baffle area for the radiator.
Most radiators can be tuned with either weights or silicone, adding
material in a balanced manner until Fb is attained.
Pe
Driver's rated RMS power handling capability.
Peak
The maximum amplitude of a voltage or current.
Peak
power rating
See Maximum power rating.
Peak-to-Peak
power rating
A totally unreliable value of rating power
amplifiers, often 4 times (or more!) the actual RMS output. See
WLS.
Phase
Coherence
The relationship and timing of sounds that come from different
drivers (subs, mids, tweets) mounted in different locations in
the vehicle.
Phase
Distortion
A type of audible distortion caused by time
delay between various parts of the signal; can be caused by equalizers.
Polarity
The orientation of magnetic or electric fields.
The polarity of the incoming audio signal determines the direction
of movement of the speaker cone. Must be observed when wiring speakers,
so that they are "in phase". See Out of Phase.
Ported
Enclosure
A type of speaker enclosure that uses a duct or port to improve
efficiency at low frequencies. Excellent design for lower power
systems, as the port often adds up to +3 dB to low frequency efficiency.
F3 can be set considerably lower with proper design, although low
frequency roll-off is generally -24 dB/octave. Good transient response
with proper tuning, although the driver loses damping below the
tuning frequency. Excellent power handling about Fb, but source
material or frequencies below Fb cause the driver to progressively perform
as if it were not enclosed at all. Due to this, ported enclosures
without a low frequency filter may have lower power handling compared
to other designs. More difficult to properly build and tune than
a sealed enclosure, with several "optimum" alignments available
depending upon the Qts of the driver. I highly recommend Vance
Dickason's "The Loudspeaker Design Cookbook," which
goes into great detail concerning the different possible alignments
of ported enclosures. The best way to model these alignments is
with a software program, where changes in tuning and enclosure
size can be immediately noted. Though it can be dated to the 1930's,
the ported alignments were thoroughly researched and standardized
by A.N. Thiele in the 60's and R. Small in the 70's. This work
was further expanded by D.B. Keele and others.
Power
(P)
The time rate of doing work or the rate at which energy
is used. One equation for Power:
P = Volts^2 / Impedance
Power
Line Capacitor
Wired inline on the power lead with your
car amp, this device stores current for instant release when short
bursts of energy are needed to produce loud, deep bass notes. Best
to mount as close to amp as possible.
Pressure
Effect
In sealed box designs, the pressure build-up on one side of the
cone which may cause non-linearity and inhibit dynamic range in
the low bass.
Push-Pull
Configuration
One driver is mounted normally, the second is mounted so that it
faces into the enclosure, both sharing the same
internal volume and wired out of phase with one another. Although
electrically out of phase with one another, the drivers are acoustically
in phase since they move in the same direction. This alignment
theoretically reduces second order harmonic distortion. Bob Carver
has done a great deal of research into this area, and has manufactured
the Sunfire True Subwoofer, a unique push-pull design that utilizes
a special passive radiator. Check out the white paper description!
Wow!
Q
The magnification of resonance factor of any resonant device or
circuit. A driver with a high Q is more resonant than one with
a low Q.
Qes
The electrical Q of the driver.
Qms
The mechanical Q of the driver.
Qts
The total Q of the driver at Fs. Qts
= Qes x Qms/Qes + Qms.
Qtc
Value for the damping provided for a driver
in a sealed enclosure. Denotes the enclosures ability to control
the driver response at resonance. Qtc = 0.707 is the optimum value
for sealed enclosures, providing flattest response and highest
SPL for deep bass extension. Enclosures for this value are often
rather large. Lower Qtc can give even better transient response,
down to a Qtc of 0.577 for the best damping and transients, but
the enclosure is usually huge and SPL's are down. A Qtc of 1.0
is a compromise between deep bass and transient response vs. smaller
sized enclosure. Larger subs can go with an even higher Qtc, as
their resonant frequency is often very low, but Qtc's above 1.5
can begin to sound very muddled and boomy, and sacrifice deep bass
extension and transient response for enhanced mid-bass peaks (louder).
Rear
fill
In autosound, the ambience created by a pair
of rear speakers that helps complete the soundstage. A set of high
quality components for the front powered by an external amp and
a set of coax mounted on the rear deck powered by the head unit
or small amp is a good example of a rear fill application. Rear
fill speakers should be faded so that they create a richer ambience,
but you should not be able to isolate any sounds coming from them.
Resonance
The tendency of a speaker to vibrate most at a particular frequency.
Resonance
Frequency
The frequency at which any system vibrates
naturally when excited by a stimulus.
Resistance
(Re)
In electrical or electronic circuits, a characteristic
of a material that opposes the flow of electrons. Speakers have
resistance that opposes current.
RMS
An acronym for "root mean square." Used in audio to help rate the
continuous power output of an amplifier or input capability of
speakers. This is the preferred method for comparing anything in
audio applications.
Roll-off
(cut-off)
The attenuation that occurs at the lower
or upper frequency range of a driver, network, or system. The roll-off
frequency is usually defined as the frequency where response is
reduced by -3 dB.
S or (Q')
The overall damping of a 4th order bandpass
enclosure. i.e., if you were to figure a 4th order bandpass enclosure
with a Qtc of 0.70 for Vr (the sealed chamber), then you would
also figure Vf (ported chamber) with an S of 0.70.
Sd
Effective piston area of a driver.
Sealed
enclosure
Air tight enclosure that completely isolates the back wave of the driver
from the front. Very tight, defined sound (with Qtc = 0.707) with
very good transient response and power handling. Low frequency
roll-off is at -12 dB/octave. Less efficient than other designs,
and higher distortion levels at resonance. Easy to design and build.
Originally this design was pioneered and marketed by companies
like Acoustic Research. See Qtc.
Signal
The desired portion of electrical information.
Signal-to-noise
(S/N)
The ratio, expressed in dB, between the signal
and noise.
Sine
wave
The waveform of a pure alternating current
or voltage. It deviates about a zero point to a positive value
and a negative value. Audio signals are sine waves or combinations
of sine waves.
Single
Reflex Bandpass Enclosure
Sometimes called a 4th order bandpass. A design where the driver
is completely "buried" in the enclosure, mounted in a sealed
chamber (Vr) and firing into a second ported chamber with the sound
emanating from one or more ports. This second chamber (Vf) is tuned
to the sealed drivers Fcb. Band-pass enclosures pass only a limited
range of frequencies, negating the need for crossovers in the circuit.
In a typical single reflex bandpass, the cutoff rate below and
above the "pass-band" is at a rate of -12dB/octave. These designs
are very efficient within the operating bandwidth, with superior
power handling, but generally inferior transient response to sealed
(all the sound has to come out of the vent). Transient response
can be very good if the enclosure is configured with a S of 0.70.
Can be very difficult to design and build. These enclosures have
been around since the 1950's, and companies like KEF helped
pioneer the manufacture and marketing of this design. See also
Dual reflex bandpass.
Skin
Effect
Technically, a physical phenomenon that relates
to the limited penetration into a conductor of an RadioFrequent
signal according to its frequency. In a direct current case everything
is constant and so nothing seems to happen. With an alternating
current, however, there is a delay in the magnetic field's response
to the change in current and the 'old' magnetic field tends to
push the current towards the outside of the conductor. As the frequency
increases, so does the effect until at very high frequencies the
entire current flows in a very narrow skin on the conductor - hence
the name. Skin effect is negligable in car audio applications.
Sound
Pressure Level (SPL)
The loudness of an acoustic wave stated in
dB that is proportional to the logarithm of its intensity.
Sound
Stage
The sound systems ability to correctly place
instruments on an imaginary soundstage; reproduction of the way
the music would sound if you were actually watching the musicians
play in front of you. The stage should always appear to be in front
of you, with a proper "image" of where each musician is playing
on the imaginary soundstage.
Spider
The flexible material that supports the former, voice coil, and
inside portion of the cone within the speaker frame.
Standing
wave
A buildup of sound level at a particular frequency that is dependent
upon the dimensions of a resonant room, car interior, or enclosure.
It occurs when the rate of energy loss equals the rate of energy
input into the system. This is what you hear when you listen into
a sea shell.
Sub-bass
Portion of bass that is very low, usually
from 20 Hz - 100 Hz or so.
Subwoofer
A loudspeaker designed to reproduce sub-bass frequencies.
Surround
(suspension)
The outer suspension of a speaker cone; holds
the diaphragm in place but allows it to move when activated. Usually
made of foam or rubber.
Surround
Sound
Usually representative of the monophonic sound extracted from the
stereo signal sent to smaller rear or side speakers used in a home
theater.
Thiele/Small
parameters
Numbers that specify the behaviour of drivers, as defined and analyzed
by two engineers, Neville Thiele and Richard Small. See Driver
Parameters.
Three-way
A type of speaker system composed of three
ranges of speakers, specifically a woofer, midrange, and tweeter.
Total
Harmonic Distortion (THD)
The percentage, in relation to a pure input
signal, of harmonically derived frequencies introduced in the sound
reproducing circuitry and hi-fi equipment (including speakers).
Transient
Response
The ability of a speaker to respond to any
sudden change in the signal without blurring (smearing) the sound.
Transmission
Line Enclosure
A design in which the driver is at one end
of the enclosure, with an internal path which consists of a series
of bends or curves that lead to a port at the other end of the
enclosure. The path length is a fraction of the wavelength at low
frequencies. The length of the path is increased by stuffing the
box with either long fiber wool or polyester batting, and produces
a phase shift in the back wave that reinforces bass at low frequencies.
Enclosures must be very large, but low end response of these systems
is legendary among audiophiles. Drivers with Qts of less than 0.4
that work well in ported should work well in these designs, but
no standardized method for configuring these enclosures exists
that engineers have yet to agree upon. Power handling is generally
less than in other designs, but drivers may be capable of responding
down to Fs. One of the most difficult enclosures to design and
build, and much experimentation may be necessary to get things
right. "Labyrinths" and "Tapered (Stuffed) Pipes"are both variants
of this type of enclosure.
Treble
(highs)
The upper end of the audio spectrum reproduced by tweeters, usually
3 - 4 kHz and up.
Triaxial
driver
A speaker that is composed of three individual
voice coils and cones; used for the reproduction of sounds in three
segments of the sound spectrum.
Tri-way
output
When a special passive crossover is used
with an automotive amplifier to safely power a subwoofer in bridged
mono (low pass circuit) as well as a pair of stereo speakers (high
pass circuit). Normal inductors and capacitors can be used for
Tri-way output.
Tweeter
A speaker designed to reproduce the high or treble range of the
sound spectrum.
Two-way
A type of speaker system composed of two
ranges of speakers, usually a woofer and tweeter.
Vas
The equivalent volume of compliance, which specifies a volume of
air having the same compliance as the suspension system of
a driver.
Vb
Total box volume, usually in cubic feet or liters. Used specifically
in sealed and ported designs.
Vf
Front volume of a bandpass design.
Vr
Rear volume of a bandpass design.
Voice
coil
The wire wound around the speaker former. The former is mechanically
connected to the speaker cone and causes the cone to vibrate in
response to the audio current in the voice coil.
Volt
(E)
A unit of measurement used to measure how
much "pressure" is used to force electricity through a circuit.
Watt
A unit of electrical power. A watt of electrical
power is the use of one joule of energy per second. Watts of electrical
power equals volts times amperes.
Wavelength
The length of a sound wave in air. It can
be found for any frequency by dividing the speed of sound in air
(1120 feet per second) by the frequency of the sound, or: WL
= 1120 / Freq.
Whizzer
A small supplementary cone attached to the center of the speaker's
main cone for the purpose of increasing high frequency response.
WLS
When Lightning Strikes. The power ratings that you see provided
on head units or cheap amps and stereo equipment that means
absolutely nothing. If you see equipment with an impossible
exaggerated rating, just say no. OK, I made this one up, but
I think it is rather appropriate. Maybe the Federal Trade Commission
will see this page…
Woofer
A bass loudspeaker designed to reproduce
low-frequency sound only. A woofer and subwoofer are usually the
same type of loudspeaker, but their application (crossover frequency)
differentiates them.
Xmax
Maximum linear cone excursion of a driver, measured in inches or
millimeters. Check out what JL Audio has to say about Xmax and acoustic output
relationships!
** All
the information that is reported here is compiled
from various sources (books - Internet)
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