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This list of information, was put together by experts in the electrical properties. The information was obtained from only the best, and most reliable sources. The sources are at the back of this packet, in alphabetical order.

NOTE: DUE TO BRIAN'S HOMEPAGE BEING REMOVED, SEVERAL IMAGES WILL NOT APPEAR. EMAIL BRIAN IF YOU WANT THEM TO COME BACK, PLEASE. 11/4/99

This packet was co-edited by Brian Beaudry and Kevin Flinn. Last HTML update: 7/24/00

Table of Contents

Definitions

Formulas

Improvements/Recomendations

Troubleshooting

Appendixes

References

Index


Return to Kevin Flinn's Audio Home page


Definitions

All definitions are in alphabetical order.

Acoustic or Mechanical Feedback: An annoying low frequency interference created when vibration from loud speakers are picked up by the cartridge and amplified by the sound system. Physically sparating loudspeakers and record-playing equipment will solve the problem. (D-75).

Active Equalizer: An equalizer that requires power to run. It is the most common kind of EQ found today. You will see these in home audio systems, car audio systems and professional systems. Most operate at a "line level," meaning either +4dBu (Pro) or -10dBu (home). The opposite of active is passive (see Passive for more). For simplicty sake, your car or home stereo probably has bass and treble controls; those are considered active.

Acoustic Suspension: A type of enclosure that is a sealed, airtight box, where there is a quick-responding, tight bass response. Usually less efficient than bass reflex designs, it requires a little more power. (Crutchfield).

Amplitude Modulation (AM): The encoding of a carrier wave by alteration of its amplitude in accordance with an input signal. (Amplitude).

Balanced Input: A three wire input system where the voltages and currents in two of the wires are equal in magnitude but opposit in polarity with respect to ground which is the third wire. The impedance of a balanced input is usually low. (600 ohms or less). (D-75).

Bandpass Filter: A filter that allows transmission of alternation signals whose frequencies are between given upper and lower cutoff values, while substantially attenuattion all frequencies outside this band.(D-75).

Bass Reflex: An enclosure that uses a tuned port to produce more bass output in a "tuned" frequency range. A very power-efficient design, it delivers louder sound from low-powered receivers or amps. (Crutchfield).

Biamp: The use of independant amplifiers to feed the bass and treble portions of a loudspeaker or loudspeakers with a crossover network. The purpose is to eliminate crossover distortion. (D-75).

Bridged Power: In mono mode, you "bridge" (combine) the stereo output to power a single speaker. A bridged amp gets half the rated impedance of a speaker. Be sure to maintain an acceptable impedance for your amp. (Crutchfield).

Channel: A channel is a complete sound path that carries a signal into your component. (D-75).

Channel Separation: Specified in dB, channel separation is the measurable output of one channel with the opposite channel's input shorted. (D-75).

Condenser Microphone: The moving diaphragm alters the distance between two metal plates. The result is a proportional change in the capacitance of the plates. (Mimms). These microphones normally sound crisper and cleaner than dynamic microphones, but are more fragile and sensitive to moisture.

Corner Frequency: A frequency at which the filter goes from a condition of passing the signal unattenuated to "rolling off" or attenuating the signal according to its frequency. It is sometimes referred to as the "cutoff" frequency or the "break" frequency. It is also defined as 3dB below the maximum output. (D-75).

Crossover Frequency: The frequency at which the upper and lower drivers intersect.

Crossover Network: A selective network used to divide the audio frequency output of an amplifier into tow or more bands of frequencies. The band below the crossover frewquency is fed to the lower driver while the high frequency band is fed to the upper driver. Also called dividing network and loudspeaker dividing network. (D-75).

Crosstalk: Signal leakage from one channel into another. (D-75).

D/A: Digital to Analog system. Used to convert a digital, binary, system into a varying voltage electric signal. (Macaulay).

Damping: Controlling of vibrations, response, or resonances which if unchecked would cause distortion. (D-75).

Damping Factor: A numerical indication of an amplifier's ability to decrease unwanted loudspeaker movements. Damping factor can be found by dividing the load impedance by the amplifier's output impedance. (D-75).

Decibel (dB): A numerical expression of acoustic or electrical ratios, such as the relative intensity of a sound or the relative strength of a signal. One to three decibels (dB) is about the smallest change in sound perceptible to the ear. (D-75).

Distortion: Unwanted noise or sounds (refer to Section C: Trouble- shooting).

Dolby Noise Reduction: Decodes Dolby-encoded tapes during playback to virtually eliminate tape hiss. Used on consumer gear and on professional gear.(Crutchfield). See figure A-1.

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Figure A-1.

Dolby B: The most widely used noise reduction system. (Crutchfield). Reduces high frequency noise by a factor of 5 to 10 dB; this is equivalent to the noise being reduced by about half of its perceived intensity. Dolby B may be played back on non-Dolby decks with only slight sonic aberration. (cassette). See figure A-1.

Dolby C: Reduces both midrange and high-frequency noise by about 10 dB, but sounds subjectively like it reduces noise twice as much as Dolby B. It also lowers distortion on high-frequency peaks. While Dolby C-encoded tapes can be played back with some success using Dolby B, they sound unpleasant when played back on decks that lack Dolby decoding. (cassette). See figure A-1.

Dolby HX-Pro: A headroom-expansion (HX) system that, unlike noise-reduction systems, works only while recording, and thus needs no decoding on playback. Dolby HX-Pro adjusts the recording current, or bias, to allow higher levels of high frequencies (treble) on the tape while lowering distortion. A byproduct of this is a subtle improvement of signal-to-noise ratio. A cassete deck with HX-Pro will greatly assist your efforts to make superior tapes. (cassette). While improving the high- frequencies, it also helps eliminate low-frequency distortion. (TD-W217).

Dolby SR: A professional noise reduction system used to increase the signal-to-noise ratio of analog tape.

Dolby Surround Pro Logic: For home theater, Dolby Pro Logic has a center channel for on-screen sound, front left and right channels for sound that moves with the action, and a surround channel for ambience and effects. (Crutchfield).

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Dynamic Microphone: A small coil moves through a magnetic field as the diaphragm moves. This causes a propotional output current to be generated. (Mimms).

Dynamic Range: A measure of how wide a range of sounds, soft to loud, that are reproduced. Higher decibel (dB) ratings indicate greater ability to recreate the wide dynamic range or you system. (Crutchfield).

Equalization: Frequency manipulation to meet the demands of recording, and an inverse manipulation on playback to get uniform response. Also known as compensation. (D-75).

Flutter: Rapid variation in the speed of a turntable or tape transport. When pronounced, flutter causes a wavering of musical pitch. (See: Wow & Flutter) (D-75).

FM Mono Sensitivity: This figure tells you how well a receiver can pick up FM radio signals. Smaller values are better -- they indicate an ability to pick up weaker stations. Expressed in decibel femtowatts (dBf). (Crutchfield).

Frequency Modulation (FM): The encoding of a carrier wave by variation of its frequency in accordance with and input signal. (Amplitude).

Frequency Response: Expressed in Hertz, this indicates the range of sounds low to high, a stereo component can reproduce. The wider the range the better. Most humans can perceive sounds from 20 to 20,000 Hz. The lowest note on a bass guitar is about 41 Hz. Most male vocalists have a range between 100 and 500 Hz. Cymbals hit about 15,000Hz. (Crutchfield). Sometimes this rating will also include amplitute variation ratings.

Gain: The ration of an amplifier's output voltage to its input signal.(D-75).

Graphic Equalizer: EQ that has set frequencies to adjust in a "graphic representation" of what is being cut and boosted. A graphic EQ has it's bands (or frequencies), spread apart in a way called per-octave. A 10-band graphic EQ has one band for each octave. Say the first band is 25 Hz, the second band would be 50Hz, and the third would be 100Hz, and so on. They have digital EQ's that can have as many as 60 bands, which is considered a 1/6th octave graphic equalizer. A graphic EQ, is mainly what is found in home systems and car stereo systems. The graphic EQ is probably the most easiest to understand, and the most common.

Headroom: Stated in dB, headroom is the difference between the average sound levels and the peak levels in a program. (D-75).

Hertz (Hz): Expressed in cycles-per-second [Heinrich R. Hertz]. (D-75, Amplitude).

Impedance (W): The load value (in ohms) the speakers present to the amplifier. (Crutchfield). Make sure you check your amplifiers impedance ratings before using speakers. It is okay to go over the impedance rating of your amplifier, but may lower the sound quality.

Input Sensitivity: The input voltage required to drive an amplifier to its fullest rated output. (D-75).

Midrange: In a 3-way system, this driver handles most vocals and much of the instrumental range, except extreme highs and lows. (Crutchfield).

Millivolt (mV): One thousandth of a volt.

Passive: Meaning not active ;-). It requires NO power to operate, the signal goes through and comes out EQ'd (and a lower level). This is done by using inductors (coils) and capacitors. This process is mainly used in crossover systems inside of a speaker box for example. Since there is loss present when using a passive system and the cost of components is high, active is preferred.

Parametric Equalizer: This one of the most complicated EQ's of them all. A parametric EQ allows you to change what frequency you want to adjust (boost or cut). A "fully parametric EQ" allows you to change the Q or bandwidth of the frequency you are adjusting. This can make the cut real narrow or real wide, covering a 10th of an octave, or covering several octaves.

Peak Power: The amount of power measured during a brief musical burst, like dramatic drum accent. Not as significant as the RMS figure. (Crutchfield).

RMS Power: The amount of continuous power, measured in watts, that an amplifier produces. The higher the RMS figure, the louder and cleaner your music sounds. The RMS figure is more significant than the peak power figure. (Crutchfield).

Selectivity: The ability of a tuner to pick up and isolate stations that are close in frequency to each other. It is quoted in dB; the higher the number, (60dB or more) the better. (Stereo).

Sensitivity: Measures how well the system converts input power into sound. The higher the number, the more efficient (i.e. louder) the speaker. (Crutchfield).

Signal-to-Noise Ratio (S/N): A measure of how well a cassette deck or CD player silencesbackground noise. Higher ratings in decibels (dB), indicate less noise. (Crutchfield). The -20 dB recording level is normally used as a reference to determinaning the S/N ratio. (cassette).

SPL: A sensitivity rating for loudspeakers. The higher the number, the more efficient the loudspeaker is at turning amplifier power into sound. (Crutchfield).

Stereo: Two separate signals, one left and one right that are used to make sound more "life-like" (e.g. the human has two ears). (Macaulay).

Stereo separation: The amount of separation between the left and right channels (or the difference between them.) The higher the number the better the separation. (Stereo).

Tape Monitor Loop: A set of output and input jacks that allow you to interpose and external audio component in the signal path of an amplifier to monitor recordings as you make them or to process the signal through a device, such as a graphic equalizer. (Stereo).

Total Harmonic Distortion: Amount of change in harmonic content of the signal as it Distortion (THD): amplified. A lower figure indicates less change and a more accurate amp. THD below 0.10% is inaudible. (Crutchfield).

Tweeter: A small, lightweight driver for reproducing the highest musical frequencies of violins, cymbals, female vocals, etc. (Crutchfield).

Voltage: Electromotive force of potential difference [Count Alessandro Volta]. (Amplitude). Referred to as "potential" energy. (Mims).

Watt: Work that has been performed by an electrical current; a unit of power. [James Watt]. (Amplitude, Mimms).

Wattage: It takes 10 times the power to double the volume, but a small increase in power can mean a big improvement in sound quality.

Woofer: This driver uses a large cone to move the big volume of air necessary to reproduce the long wavelengths of bass instruments and drums. (Crutchfield).

Wow & Flutter: A measurement of tape-speed fluctuation. It is usually listed as a percentage, followed by WRMS. (cassette). The lower the percentage, the better. (Crutchfield).

 

Formulas

A list of formulas that deal with electronics and sound systems.

Ohm's Law

The formulas for finding wattage (Power) are: P = IE or P = I2R.

The formula for finding the ohms in a series circuit is:

ZT = Z1 + Z2 . . . . + Zn

Where Z is the impedance of the speaker.

The formulas for obtaining the ohms in a parallel circuit are:

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For only 2 speakers in parallel use the formula:

(Z1* Z2) / (Z1 + Z2)

To find the damping factor all you have to do divide the load impedance by the amplifier's output impedance. (D-75).

 

Improvements/Recomendations

This section gives suggestions on improvements you can make to your system and recomendations that will make it work to its fullest potential.

Suggested speaker wire gauge vs. the number of feet.

Max. wire length Wire gauge (AWG)

up to 24 feet                  18

up to 36 feet                  16

up to 57 feet                  14

* It is suggested to use multistranded copper wire for any speaker applications.

* If copper wire is corroded at the speaker connection, then strip away until shiny wire appears. (Ultimate).

* The distance between the two speakers should be less than the distance between your listening position and the point between your two speakers. (Ultimate).

* Your listening position should not be against a wall. (Ultimate).

* To find the polarity of a speaker, mommentarily touch the speaker terminals to a 1.5 volt battery in which the positive lead goes to the speaker terminal that makes the speaker move outward. Once you have found that, the positive of the battery indicates the positive of the speaker. If it moves inwards then it is backwards and you must reverse leads. (Speaker).

* Make sure the impedance of your speakers matches the impedance of you amplifier.

* When turning on sound equipment, make sure that the amplifier is turned all the way down. NOTE: Failure to do so may cause damage to speakers and amplifier.

* To obtain the maximum sound out of your speakers, place them at ear-level. (Ultimate). If it means to put them on stands, it is suggested to do so. Make sure your stand is strong enough to hold you speakers.

 

Troubleshooting

Refer to this section if you are experiencing problems while hooking up or operating a sound system.

Make sure your speakers are in-phase--positive of amp to positive of speaker and common to common.

If speaker wire ever feels warm to the touch, then replace with a higher gauge. The warmth is due to running more power through wire than it can handle. Not replacing the wire may cause damage to your amplifier and will lower the sound quality of your system.

If speakers are sounding distorted then turn down the amplifier until distortion is eliminated. The distortion may be caused by too high of wattage into the speakers. If distortion persists, you may have a blown speaker or amplifier. If this is the case, replace the driver immediately to avoid further damage to the amplifier.

If you are having problems you just can't diagnose, then email me...
soundman_144@yahoo.com

 

Appendixes

 

Appendix I: References

"Amplitude Modulation","Hertz","Volt","Frequency Modulation","Watt." Webster's II New Riverside University Dictionary. Eds. Anne H. Soukhanov and Kaethe Ellis. Boston: The Riverside Publishing Company, 1984.

"Cassette Decks." Consumer Guide 124-127.

Crutchfield Winter/Spring 1997: 7,21,49,53,82,99,106.

"D-75 Dual-Channel Power Amplifier." Crown Instructional Manual. Crown International INC.: 1-2 - 1-3.

"Speaker Installation Instructions." Bogen. Lear Siegler, Inc., Bogen Communications Division, September 1968.

"Stereo Receivers." Consumer Guide 104-107.

"TD-W217/W218 Double Cassette Deck." JVC Instructions. Victor Comany of Japan, Ltd.: 8.

"Ultimate Test CD, The." The Special Music Company, 1993.

Macaulay, David. The Way Things Work. Boston: Houghton Mifflin Company, 1988.

Mimms, Forrest M. III. Getting Started in Electronics. 11th ed. 1993.

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