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Links Altoparlanti
Indice
General articles
Speaker placement tips
Speaker product information
History
The ugly truth: Any length of speaker cable degrades performance and
efficiency. A simple fact to remember on speaker cables: Current needs copper, voltage
needs insulation.
Copper is a very good conductor of electricity, but it isn't
perfect. It has a certain amount of resistance, determined primarily on its
cross-sectional area (but also by its purity and temperature). This wiring resistance is
"seen" by the amplifier output as part of the load in sreias of the actual load.
Since increasing the load impedance decreases current flow, decreasing power delivery, we
have lost some of the amplifier's power capability merely by adding the series resistance
of the cable to the load. There is a definite impact on the amplifier damping factor
caused by cabling resistance/impedance. Damping, the ability of the amplifier to control
the movement of the speaker, is especially noticeable in percussive low-frequency program
material like kick drum, bass guitar and tympani. Boomy, mushy bass is the result of poor
damping and clean "tight" bass is a sign of good damping at work. In short, you
need thick enough wires and you are happy with the losses caused by resitance and on the
damping factor. Aonither rule of thumb is that 4-ohm load should require conductors with
twice the copper of an 8-ohm load, assuming the length of the run to the speaker is the
same and you want same performance.
The extremely low impedance nature of speaker circuits makes cable
capacitance a very minor factor in overall performance and the dielectric properties of
the insulation used are nowhere critical on speaker cables compared to the effect of
speaker wire resistance. If the spaker cable is going to be soldered to the connector the
most important consideration for insulation for speaker cables is then probably heat
resistance (so that the cable insulation van take the soldering temperature nicely).
Banana plugs(4mm diameter) are very traditional speaker connectors.
Banana plug is good connector for speaker signals, both mechanically and electrically. You
can see those connectors on many audio amplifiers and speakers. Banana plugs make reliable
connection and those connectors are available in hifi industry for even very thic cables.
In Europe the audio industry is moving away from banana connectors. European safety
standard EN 60065 for consumer electronics effectively bans the use of the 4mm 'banana'
type plug commonly used for connecting loudspeakers to amplifiers. The reasoning behind
the prohibition of cable-mounted 4mm (and smaller-sized) plugs is that they can be
inserted into a European mains socket with possibly fatal consequences.
Audio industry seems to be moving away from banana connectors and
replace them with other alternative. There has been many ideas what this connector coul
be. Professional audio industry seems to prefer Speakon connector. For home HiFy systems
there is no uniform wiring standard (other than insulated screws which take bare wire).
You should always use the recommended load for your amplifier. This
means selecting suitable speaker type or wiring multimpe speakers in the right way. Most
solid-state amplifiers would rather look at an open circuit (no speaker at all) than a
load. Therefore, you can usually use a load that is higher than the recommended load
without any problems or damage. Most powerful tube amplifiers need a load to avoid
transformer or tube socket damage. If a mismatch can not be avoided on a tube amp, it is
usually better to go towards a lower impedance rather than too high of a speaker impedance
(this may stress the tubes more than normal operation).
How to read speaker specs
Typical specifications on speakers you can see is impedance, power
rating, recommended amplifier power, frequency response, distortion and effiency. You can
often see also other specifications.
Impedance is the AC equivalent of resistance in a DC circuit.
Speaker impedance is usually largely dependent on frequency. The impedance rating told on
speaker specifications is the "average impedance" (the impedance stays in the
operation usually at higher or lower than this, but generally stays above 75% of nominal
impedance). Generally when you are buying or connecting a speaker to an amplifier, check
that the speaker impedance is equal or higher than that is the lowest allowed impedance on
your amplifier intended to drive those spakers (some aplifiers are limited to 8 ohms, some
other can go to 4 ohms or even lower).
Often used speaker power handling capacity test standard is IEC
268-5, which specify filtered pink noise test signal. The nominal power (RMS power) for
speakers is defined by supplying continous power is measured by pink noise rather than a
sinousoidal signal and it is applied for 24 hours. Maximum power rating is 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.
Frequency Response is the frequency range to which the speaker can
respond. Full-range speaker is a speaker designed to reproduce all or most of the sound
spectrum within human hearing (20Hz - 20KHz). Typical speakers are not able to play back
this whole frequency range.
Harmonic Distortion means that harmonics are artificially added by
the non-linearities of thespeaker, and are generally undesirable (but can not be
completetely avoided). It is expressed as a percentage of the original signal.
Loudspaker effiency
Speaker impedance details
The loudspeaker element involves electromechanical processes where
the amplified audio signal must move a cone or other mechanical device to produce sound
like the original sound wave. This process involves many difficulties, and usually is the
most imperfect of the steps in sound reproduction. An enormous amount of engineering work
has gone into the design of today's dynamic loudspeaker.
Dust cup in spaker element is sometime talked about. The function of
the dust cup is dust and other foreign matter out of the voice coil gap. Any small grit
that gets in there could easily lodge in the gap and cause distortion and possible
failure. Additionally, depending upon the design, it could seal the enclosure and it could
be used to radiate higher frequencies on some speaker elements.
Once you have chosen a good loudspeaker element from a reputable
manufacturer and paid a good price for it, you might presume that you would get good sound
reproduction from it. But you won't without a right enclosure. Right type of enclosure is
an essential part of sound production.
General information
Information on speaker element parameters
Speaker element parameter lists
General tutorials
Enclosure design
Crossover design
Speaker building sites and tips
Other useful pages
General speaker measurement information
Speaker element parameters
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Measuring Loudspeaker
Parameters - There are several different ways to measure the Thiele/Small parameters
of a loudspeaker driver. The method described here provides a way for the beginner and DIY
enthusiast to measure the parameters without any expensive or specialised equipment.
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Measuring
speaker parameters - it's possible to get most of the Thiele-Small parameters from a
loudspeaker by just accurately measuring the impedance versus frequency
Measurement software
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Audia Speaker Workshop - you can
download alpha release of the software, read also How to use Speaker Workshop from Audua
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DAQARTA - Real-time FFT
spectrum / color spectrogram / waveform display on any DOS system, using popular sound
cards or laboratory data acquisition board
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LoudSpeaker LAB
English version 2.0 homepage - new version of a good loudspeaker measurement software
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Energy Time Frequency
- measure room acoustics and speaker response, free demo version available
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Liberty Instruments Test Suite
- commercial measurement software and hardware solution, performs with similar features to
MLSSA, free demo version downloadable
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Sound Technology -
makes measurement software, free demo versions available
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Microacoustics PC
AUDIO LAB version 1.1 - speaker and acoustics measurements using Soundblaster 16 or
Media Vision PAS16
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WINSWEEP -
loudspeaker and acoustics measurement software, web pages in German, try automatic
translation to English, demo version available, but it can't do real measurements
Other related software and utilities
Downloadable software for PC
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Audua Speaker Workshop - design
and analysis software, free pre-release version available for downloading, measures
speaker element parameters, take also look at How to use Speaker Workshop from Audua
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Bill McFadden's Home
Page - speaker element specifications and box design software
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Bullock & White
Software - DOS BoxModel, Windows BoxModel demo, driver database, system and lattice
simulator, speaker models, Delphi math units
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CALSOD page by Sonic
Design - program for computer-aided loudspeaker system optimization and design, free
demo available
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Eminence
Designer Demo - This is a "demo" version of the Eminence Designer bass
speaker design program. This demo version includes the information for the Eminence Sigma
Pro-18 woofer. This is the only driver that can be used in the demo program.
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Hi-Fi A/V Software
- Visual Ears speaker in room simulator and speaker design programs
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Home Theater /
Audio / Video Related Computer Software - spaker placement and speaker design
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HornCalc for
Windows 95 and NT - calculates the tractrix horn contour, free demo available
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JBL-Smaart
- Practical Windows® Based Sound System Optimization and Acoustical Analysis Software,
free demo available
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LspCAD Professional
- commercial software, free demo available
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Speaker
designing software from rec.audio.high-end
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Speaker Workshop - speaker design
software, alpha versio available for downloading
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SubWoofer
Designer - Software to design a subwoofer. This program includes simulation and
generates a picture of subwoofer design.
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Wayne's World
Program Archives - lots of speaker design and modeling software
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WinISD - Windows
version of Interactive Speaker Designer speaker designing program
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Winsub Subwoofer
Designer - for Win95/NT
On-line web based software
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