# Glossary and Acronyms Help Wanted



## Sonnie (Apr 11, 2006)

We have started a Glossary and Acronyms page ... Glossary (Link is also in the navigation bar menu up top.).

We are looking for related words/terms and/or acronyms that can be added. If you know of any, please post them here in this thread and we will review the suggestions for addition to the glossary.

Thanks!


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## Ayreonaut (Apr 26, 2006)

*DRC*
Dynamic Range Control (Dolby Digital)


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## Sonnie (Apr 11, 2006)

Added! 

Thank you!


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## Wayne A. Pflughaupt (Apr 13, 2006)

CRT – you might add that this is the screen (display?) that TVs and personal computers have used since their conception (until recently). Basically consists of three “guns”, red, green and blue. Brucek can probably give you a better technical description of them, but it needs to be brief and concise for this.

By the way, how does Dynamic Range Control add up to Dolby Digital?

Regards,
Wayne


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## Wayne A. Pflughaupt (Apr 13, 2006)

ghz – needs to be gHz

Regards,
Wayne


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## Sonnie (Apr 11, 2006)

Added CRT definition:
Cathode Ray Tube - A vacuum tube in which a hot cathode emits a beam of electrons that pass through a high voltage anode and are focused or deflected before hitting a phosphorescent screen. The original screens/displays used for computer monitors and televisions consistig of a red, green, and blue color lense.


Corrected GHz, added Hz and KHz (already had MHz).


I'm not familiar with DRC... maybe Naut can elaborate.


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## Fincave (Apr 20, 2006)

*SWMBO* She who must be obeyed. Always makes me laugh.


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## Sonnie (Apr 11, 2006)

This was all your idea to begin with if you remember.

How about *SWAMP* ???


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## eddthompson (Aug 19, 2006)

you missed DTS :bigsmile: 

also mpeg, for motion picture experts group, and its derivative mpeg-1. mpeg2, mp3, mp4 etc, all codecs 

VC-1 and AVC new codecs on bluray/hd-dvd.

Anamorphic, widescreen enhanced thingy 

DAC digital to analogue converter.

CD compact disc

DVD, digital versitile disc, or something dumb like that.

THX more lucas world domination

dB decibel.

im sure you can phrase these better :dumbcrazy:

all i can come up with.

edd


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## eddthompson (Aug 19, 2006)

few more:

spl, sound pressure level

sxrd, the sony display thing.

LD laserdisc, a mystic device of an av time long gone.

RF Demodulator, some kind of voodoo box asociated with laser discs and DD, and non av types to connect dvd players to old tvs.

Gamma see http://en.wikipedia.org/wiki/Video_gamma


Id also add that rca is a kind of connector usualy for sound and component video.

edd


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## lcaillo (May 2, 2006)

That would be RF Modulator, not Demodulator. Your tuner is a RF demodulator.


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## lcaillo (May 2, 2006)

eddthompson said:


> Gamma see http://en.wikipedia.org/wiki/Video_gamma


Also see:

http://www.poynton.com/PDFs/TIDV/Gamma.pdf


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## eddthompson (Aug 19, 2006)

lcaillo said:


> That would be RF Modulator, not Demodulator. Your tuner is a RF demodulator.



:dumbcrazy: yup, brain isnt fireing on all cylinders today

edd


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## Sonnie (Apr 11, 2006)

I've added quite a few and changed it up a little... still have a few more to add, but you can check it out.

If you believe we can improve on the definitions, please advise here and we will make the necessary changes.


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## Sonnie (Apr 11, 2006)

I couldn't find any definition for VC-1 and AVC. If someone can get me up a definition, I'll add them.  I don't even know what they are an acronym for.

I think all the rest are there.


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## lcaillo (May 2, 2006)

Sonnie said:


> I couldn't find any definition for VC-1 and AVC. If someone can get me up a definition, I'll add them. I don't even know what they are an acronym for.
> I think all the rest are there.


From the horse's mouth, or other end, depending on your computing orientation:
http://www.microsoft.com/windows/windowsmedia/forpros/events/NAB2005/VC-1.aspx

AVC could be Automatic Volume Control or a video compression algorithm:
http://www.avc-alliance.org/


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## lcaillo (May 2, 2006)

Also add Skew, Pincushion distortion, G2 Level (Screen Level)

Note that Balanced audio connections can also use 1/4" Phone jacks and plugs not just XLR.


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## lcaillo (May 2, 2006)

And one of current interest - CEDIA


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## eddthompson (Aug 19, 2006)

AVC i was refering to the video compression, i believe sony were going to use it on bluray instead of vc1, i think both are derived from mpeg4.


edd


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## eddthompson (Aug 19, 2006)

The glossary is a realy great piece of work, a true asset to the forum, well done.

edd


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## jmprader (Apr 19, 2006)

Sonnie:

How about some layman's definitions relating to subwoofer tech terms like: 
Xmax, Bl, Vas, Fs, F3, etc...might want to make them some kind of sub-category under subwoofers, IB's, etc...


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## Sonnie (Apr 11, 2006)

Thanks edd!


Yes John... that is a great idea on the TS Parameters... which is probably where they should be sub-categoried at.


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## Sonnie (Apr 11, 2006)

I found these:


Hz: The unit of measurement for frequency. 1 Hz is equal to one cycle per second, or the complete cycle of an alternating wave form per second.  
Fs: The frequency at which a speaker naturally resonates in free air. (measured in Hz) 
Fb: The resonance frequency of the air in a port and the stiffness of air in a ported system. This is commonly referred to as the Tuning Frequency of a ported enclosure. (also measured in Hz) 
Fc: The resonance frequency of the Closed-box system. 
F3: The frequency at which the acoustic power output from a system has fallen to half of its reference value. This is what we call the systems 3dB down point. (again, measured in Hz) 
Q: Yes, this is the guy that made all those fancy gadgets for 007, but that isn't what we mean here. This is actually the ratio of reactance to resistance in a series circuit, or the ratio of resistance to reactance in a parallel circuit. 
Qes: The Q of a speaker at its free air resonance, considering only its electrical losses. 
Qms: The Q of a speaker at its free air resonance, considering only its mechanical losses. 
Qtc: The total Q of a woofer and sealed enclosure (Fc) at the system's resonance frequency, considering ALL resistive losses. 
Qts: The total Q of a woofer at Fs, considering all driver (speaker) resistances. 
Vas: Volume Acoustic Suspension. This is the volume of air having the same acoustic compliance ("stiffness") as the speaker's suspension. (measured in cubic feet or liters) 
Vab: Volume of air having the same acoustic compliance as the enclosure.  
Å: Compliance Ratio 
NO: Reference Efficiency (H Greek eta). 
CAS: This the Acoustic compliance of the driver suspension. 
CAB: Ok, this MIGHT be how some of you get around after your Driving Under the Influence tickets, but this really means, Acoustic Compliance of the air in the enclosure. 
Xmax: The maximum excursion of a speakers cone in ONE direction while maintaining a linear behavior. (measured in inches or millimeters) 
Vd: This is the volume of air displaced by the speakers cone during an Xmax displacement. 
BL: The product of a drivers gap flux density and the length of the voice coils conductor in the gap. (measured in Tesla meters) Not to be confused with ** which is commonly spouted by many persons on RAC and IRC (you know who you are). 
Sd: The active radiating area of a speaker cone, including the surround. (measured in square inches or meters) Sd is also known as EPA no, not the Environmental Protection Agency, it's "Effective Piston Area" 
Re: The ACTUAL DC resistance of a speakers voice coil/s as measured with a standard volt/ohm meter. Not to be confused with Nominal impedance. A 4ohm speaker will commonly measure only 3.2ohms and an 8ohm will measure around 6.4ohms. You can use a volt/ohm meter to measure the impedance of the coil on a speaker that you are not sure the impedance of. (measured in Ohms) 
Le: The electrical inductance of a speakers voice coil. (measured in mH also known as millihenries) 
Impedance: The total opposition to the flow of alternating current in an electrical circuit. The measure of the magnitude of an electrical load when using alternating current, such as in audio. This is the combined effect of resistance, capacitance and inductance. (measured in Ohms).
RMS: This is the continuous power that the speakers voice coil can handle without failure. (measured in Watts) RMS stands for Root Means Square, but that doesn't really matter....
S Factor: A description of a bandpass enclosures frequency response in the pass band. It is a general indicator of the bandwidth. 
SPL: Everyones favorite. This is an acoustic measurement of sound energy. (measured in dB aka decibel) High dB levels (above 120dB) can cause permanent hearing damage.
SPLo: The speaker's reference efficiency measured with 1 watt input at a 1 meter distance from the center of the cone. 
dB: The basic unit of measurement in electronic and acoustic work. It can be referred to as a measure of loudness. 
Damping Factor: The ability of an amp to control the load without overhang. This applies to how tight the bass is. The higher the number the better, but anything over 50 is said to be inaudible. Damping factor is calculated by dividing the load (speaker impedance) by the output of the amplifier. As a speakers impedance decreases the amplifiers damping factor will also decrease. (not to be confused with DampENING, aka getting your amps wet, as this is a very, very, BAD thing to do to your amps) 
Vb: Internal Volume of air in an enclosure. (measured in cubic feet, or liters for you foreigners) 
Volume: The total internal airspace of an enclosure calculated by multiplying Length x Width x Height. (also measured in cubic feet or liters) (to calculate the cubic feet you must do your multiplication as described above and then divide by 1728 <---cubic inches in one cubic foot) 
HD: Hole Diameter, the actual cutout size in your baffle so your speaker will fit properly. 
MD: No, not your Doctor. This is the Mounting Depth of your speaker. 
Series: A series connection is two or more speakers or voice coils wired with the positive from one speaker/coil to the negative on second speaker/coil, thus leaving a positive from one speaker/coil and a negative from the other. 
Parallel: A parallel connection is achieved by taking all the positives from each speaker/coil and wiring them together and then doing the same for all negatives. 
DC: "Direct Current" describes a circuit in which current travels in one direction only. This current will always flow from Negative to Positive. 
AC: "Alternating Current" describes a circuit in which the voltage potential fluctuates so that current can flow in both directions through the circuit. Your amplifiers put out Alternating Current to drive your speakers.  
THD: This is Total Harmonic Distortion and represents how much a certain device (amps, etc.) may distort a signal. This is usually shown on spec sheets as .005% THD. You will want to pick a product that has low THD numbers, as these will offer the cleanest signal. It is said that THD of less than .1% is inaudible, but even though your ears may not hear it, it doesn't mean it isn't there and possibly doing damage to your speakers. Distortion is the LEADING cause of damaged speakers! 
EBP: "Efficiency Bandwidth Product" is used to help in the design of the correct enclosure for a particular driver you will be using. EBP=Fs/Qes. Numbers below 50 will be best suited for Sealed enclosures, while numbers from 50-90 are fairly flexible as far as enclosure options, and 90 and up are best suited for Vented enclosures. 

These have been added here.


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## Sonnie (Apr 11, 2006)

Still looking for additions and/or corrections. :T


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## drf (Oct 22, 2006)

how about:

ICSMMWHMWARUNP!!

It cost so much my wife hit me with a rolled up news paper!!

One suggestion I have is that under "wavelength" maybe there should be a distinction made between how light travels and its speed and how sound travels and its speed. I only say this because I know of people who have had trouble understanding accoustics because they thought light and sound operated the same way. For example the wavelength of a microwave oven, a wireless computer network and an audio signal of 2.7Khz are all 12.6CM.

My suggestion would be:

The wave length of light is the period of motion of an electromagnetic particle (photon) traveling at 186,000 miles per second. 

The wavelength of sound is the periodic propogation of atmospheric pressure travelling at 1150 feet per second.


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## Sonnie (Apr 11, 2006)

Did you mean for "wave length" and "wavelength" to be this way with the space in the first one?


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## nova (Apr 30, 2006)

How about 1080p, and class D amps.


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## drf (Oct 22, 2006)

Sonnie said:


> Did you mean for "wave length" and "wavelength" to be this way with the space in the first one?


No. Truth be told I am probably just overcomplicating things. I just thought that even though the actual definition and calculation for wavelength is the same for both, by not defining the difference between light and sound people who read the glossary could think the two are similar in others ways also. I found when studying that the number of people who treated sound as if it would react the same way as light was astounding. 

Probably best to just leave it as it is.


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## lcaillo (May 2, 2006)

Sonnie said:


> Still looking for additions and/or corrections. :T


ITU
CIE
EBU
SMPTE
CCT
D65
Illuminant
Foot-Lambert
Lumen
Illuminance
Luminance
Luminous Flux
Luminous Intensity
Radiance
Constant Luminance


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## Sonnie (Apr 11, 2006)

lcaillo said:


> ITU
> CIE
> EBU
> SMPTE
> ...


What? No definitions? You really wanna make me work huh? :nerd:


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## lcaillo (May 2, 2006)

If you think that these are appropriate entries I will put together the defininitions.


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## Sonnie (Apr 11, 2006)

Absolutely! :yes:


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## lcaillo (May 2, 2006)

ITU International Telecommunication Union http://www.itu.int/net/home/index.aspx

CIE Commission internationale de l'éclairage aka International Commission on Illumination
http://www.cie.co.at/index_ie.html

EBU European Broadcasting Union http://www.ebu.ch/

SMPTE Society of Motion Picture and Television Engineers http://www.smpte.org/home

CCT correlated color temperature - The temperature of a black body radiator that most closely resembles a given light source (Kelvin units)

D65 (correctly written with 65 subscripted) - The standard illuminant intended to represent daylight of the Northern Hemisphere sky defined by a table of spectrophotometric data over the range of visible light. It corresponds to a CCT of 6503.6K, or more significantly to display calibration, chromaticity coordinates for white of x=0.3128, y=0.3290.

Illuminant - There are two uses for the term that must be carefully distinguished. Alone, the term suggest the common useage referring to a source of light. Used as the term Standard Illuminant, or in the context of color science, it refers to a defined spectral density of visible light used as a reference for matching various light sources such as daylight. D65 is one standard illuminant, among many.

Foot-Lambert - a measure of luminance from a light source or reflected off of a surface equal to 1 Lumen per square foot.

Lumen - an SI unit of luminous flux, or perceived power, defined as 1 candela x 1 steradian cd·sr)

Illuminance - the measure of incident light on a surface describe in lux, a derived SI unit defined 1 lumen per square metre (cd·sr·m−2).

Luminance - is a measure of luminous intensity of light leaving a surface in a particular direction over a given angle of projection. The SI unit for luminance is candela per square metre (cd/m2, aka nits). 

Luminous Flux - the total perceived power (weighted for the sensitivity of the eye over the range of visible light) of light in all directions, measured in Lumens.

Luminous Intensity - the perceived power (weighted for the sensitivity of the eye over the range of visible light) of a light source over a given solid angle, measured in candelas.

Radiance - the amount of light emitted from or passing through an area over a solid angle in a particular direction, measured in watts per steradian per square metre (W·sr-1·m-2).


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