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1,499 Posts
Discussion Starter · #1 · (Edited)
AE - Acronyms Explained

Acronyms - Their initialization - Short-and-simple explanation. This collection is concentrated on acronyms commonly used in the "Audio", "Subwoofers, Bass, and Transducers", "DIY" forums.

As this for the everyone's benefit, please....
Post what acronyms you need to understand.
Post what acronyms you know, but others might not know.
Post what acronyms you can decode.
Post what the best definition is.

Reason for doing this - reading AVS I come across acronyms everyday that I don't know, and I don't want to interrupt the thread and appear a doffus for not knowing. I figured that if I don't know all the acronyms and meaning, then others probably don't either.

Note 1: A term's meaning is often dependent on the context in which it was used, as well as the (unknown) intent of the poster.

Note 2: Some of these might not technically /grammatically be acronyms, but are included anyways because they look like acronyms. See post #113. Besides, this is not a grammar forum.

Note 3: Anything done wrong is my fault. I apologize. If this was helpful to you, you're welcome.

1,499 Posts
Discussion Starter · #2 · (Edited)
?? = I don't know what the acronym stands for, or I don't have a good explanation.
The color green means a manufacturer/retailer or a manufacturer/retailer related term.
The color red means a movie. A bigger list of movie acronyms is here.

AM - Accelerometer - A device that measures acceleration. Instrument used for measuring the vibrations from a tactile transducer, or from a subwoofer.
ARC - Audio Return Channel - Device technology that uses a single HDMI connection to send Dolby Digital, PCM, or DTS audio from a TV to the AVR (or soundbar). Without ARC, 2 HDMI cables would be needed: AVR to TV, TV to AVR. All HDMI cables will support ARC functionality when connected to ARC-enabled devices.
ASIO - Audio Stream Input/Output - a computer sound card driver protocol for HDMI audio specified by Steinberg GmbH, providing a low-latency and high fidelity interface between a software application and a computer's sound card. Used in REW to control HDMI. ASIO Website
ARC - Anthem Room Correction - Anthem's AVR room correction solution.
AV - Audio Video.
AVR - Audio Video Receiver.
AVS - AVS Forum began back in 1999, when home-theater buff David Bott decided to launch a Web-based forum for like-minded aficionados in collaboration with online retailer AV Science, from which the forum's name was derived.

BB - Baltic Birch - Material sometimes used in subwoofer cabinets due to its resistance to flexing.
BB - Best Buy - Electronics / entertainment retailer. Website
BHD - Black Hawk Down - 2001 action/drama movie.
BK - ButtKicker - Brand of tactile transponders. Website
BLA - Battle: LA - 2011 action/sci-fi movie.
BVS - Batman versus Superman - 2016 action/sci-fi movie.

CACW - Captain America: Civil War - 2016 action/sci-fi movie.
CEA2010 - Industry standard for measuring output of powered subwoofers.
CSL - Cross Spectrum Labs - Seller of microphones, sound level meter, and MiniDSP 2x4. Website

dB - Decibel - A unit used to measure the intensity of a sound or the power level of an electrical signal by comparing it with a given level on a logarithmic scale. In general use - a degree of loudness. 0 dB is no sound.
dBfs - Decibels relative to Full Scale - A unit of measurement for amplitude levels in digital systems. 0 dBFS is the level of a signal that is at the maximum level your system can cope with without clipping the tips of the waveform. So -10 dBFS means a level that is 10 decibels lower than the maximum level your system can handle. In summary - decibels are used to describe differences or changes in level. 0 dB means 'no change'. Values in dBFS are used to describe signal levels in comparison with the highest level your system can handle.
DCAC - Digital Cinema Auto Calibration - In certain of Sony's AVRs, a feature that does room correction. There are different versions of DCAC that have different features.
DD - Dolby Digital - A series of lossy audio codecs by Dolby Laboratories. The abbreviation is often combined with the channel count, like DD 2.0 or DD5.1. Dolby Digital is the common version usually with 5.1 channels.
DEQ - Dynamic EQualization -Adjustment of specific frequencies based on the playback volume level.
DF - Down Firing - Subwoofer design where the driver is vertically pointed downwards (toward the ground), instead of along the horizon.
DIY - Do It Yourself - Build your own equipment.
DPL - Dolby Pro Logic - A series of audio codecs by Dolby Laboratories. Article
DSP - Digital Signal Processor - An electronics device using DSP chip(s) in order to measure, filter and/or compress continuous real-world analog signals.
DSU - Dolby Surround Upmixer - Dolby Surround is old sound codec, but in 2014 Dolby has re-used the name as part of its Atmos bundle of technologies. DSU is an upmixer designed to function with traditional channel-based layouts, as well as Atmos enabled layouts that include overhead or Atmos-enabled speakers. It processes native stereo, 5.1, and 7.1 content. Dolby Surround is a total replacement of Pro Logic.
Read more at http://www.soundandvision.com/content/meet-new-dolby-surround#iBQFty65eudAxY3D.99
DTS - Digital Theater Systems - A series of digital sound technologies (codecs) owned by the company of the same name. The acronym means Digital Theater Systems, and is a backronym for Dedicated To Sound. Website
DWH - Deepwater Horizon - 2016 action historical movie.

ELC – Equal Loudness Contour (or Curve) - Use of an ELC is an attempt to make all frequencies sound the same loudness. This is because humans perceive lower frequencies and higher frequencies (but less so) to sound not as loud as the frequencies around 1-5 kHz, particularly when at lower listening levels. Thus there are different contours for different listening levels. Often called a Fletcher-Munson curve. Some old stereos had a “loudness” button which invoked compensation based on an ELC. On a common sound level meter, A and C weighting are uses of different db ELCs.
EOT - Edge Of Tomorrow: Live Die Repeat. 2014 action/sci-fi movie.
EQ - Equalization - Process (or settings) to account for differences in speakers placement, speaker capabilities, speaker distance, and room effects (on the sound waves), in order to try to attain "better" sound. Mostly synonymous with Room Correction, but EQ is perhaps less concerned about the room.
ESL - Electro Static Loudspeaker - Speaker design which uses a thin flat membrane sandwiched between two electrically conductive grids. These speakers often look tall, skinny, very thin and semi-transparent.

F3 - Frequency 3dB - The frequency at which the driver's output is 3dB below its flat response.
FFT - Fast Fourier Transform - A algorithm that allows conversion between a time-domain analog signal and a digital representation of it in the frequency-domain (which has amplitude and phase data). 'Fast' means it is not slow. 'Fourier' was pioneering mathematician. 'Transform' means it changes.
FL - Front Left - Speaker location.
FLR - Front Left Right - Two front speakers and their location.
FOTP - Flight Of The Phoenix - 2004 action movie.
FR - Front Right - Speaker location.
FR - Frequency Response - Usually a Hertz range between which a speaker can accurately play an audio signal. Said to be about the quality of the sound.

GG - Green Glue - Noiseproofing compound. Website
GTG - Get To Gether - Meetup of some like-interested folks.

HPF - High Pass Filter - The frequencies higher than that number are passed through. The frequencies lower than the cutoff frequency are attenuated (e.g. reduced, at a rate specified by filter designer). There could be a HPF on a subwoofer, for controlling the signal sent out to surround speakers from the sub.
HSR - Hacksaw Ridge - 2016 action historical movie.
HSU - Hsu Reseach - Company that manufacturers and sell subwoofers and speakers. Company is named for founder Dr. Poh Ser Hsu. Website
HT - Home Theater - Your audio visual equipment and setup, and/or the "special" room it is in.
HTiB - Home Theater In a Box - A pre-packaged assemblage of speakers (often a 5.1 speaker setup) and perhaps a AVR. Usually the first step in a first "Home Theater".
HTTYD - How To Train Your Dragon - 2010 animated fantasy movie.
HZ - Hertz - Unit of frequency defined as one cycle per second. Examples: 20 Hz is twenty cycles per second. Deep bass. 20 kHz is twenty thousand cycles per second. High treble. In general humans can hear sounds between 20 Hz and 20 kHz.

IB - Infinite Baffle - Specifically it means to mount the loudspeaker driver in a VERY large sealed enclosure. But often it is used as a generic term for sealed enclosures of any size, the name being used because of the ability of a sealed enclosure to prevent any interaction between the forward and rear radiation of a driver at low frequencies.
ICE - ICEpower - Manufacturer of subwoofer amplifiers. Website
ID - Internet Direct. Company that sells its products via the Internet (not via brick and mortar stores).

JBL - Company (owned by Harmon) that sells audio and associated products (including subwoofers). Name is from founder's initials: James Bullough Lansing. Website
JL - JL Audio - Company that sells audio products, especially subwoofers. Name is from first name initials of founders: James Birch and Lucio Proni. Website
JTR - JTR Speakers - Company that manufacturers and sells subwoofers and speakers. Website

LCR - Left Center Right - Three front speakers and their location.
LF - Low Frequency - Non-specific term perhaps meaning audio under 200 hertz maybe down to 20 Hertz. Said to provide kick in the chest.
LFDH - Live Free or Die Hard - 2007 Action/adventure movie.
LFE - Low Frequency Effects - Technically a dedicated audio channel on a soundtrack. The . 1 in 5.1 or 7.1. In contrast to the main channels, the LFE channel delivers bass-only information (=10% THD starts to occur, or in mechanical terms. See post 44 for a better technical explanation.
XMECH - maXimum MECHanical limit - Measurement of how far the speaker's voice coil can move in one direction (its 'excursion') at which point it would hit a mechanical (i.e. physical) limit. Same as XLIM. See post 44 for a better technical explanation.
XO - Cross Over - Hertz value at which point the audio signal is switched from one speaker/driver to another.

YPAO - Yamaha Parametric Acoustic Optimizer - In certain of Yamaha's AVRs, a feature that does room correction. There are different versions of YPAO that have different features.

1,499 Posts
Discussion Starter · #3 · (Edited)
Common Terms (that aren't acronyms)

Balanced Connector - A balanced cable, has three conductors in the connector and three wires in the cable: two signals wires plus a separate ground wire. The two signal wires both carry a copy of the signal, but the two copies are sent 180 degrees out of phase with the other. Used to protect against interference ("noise").

Room correction (aka EQ, or equalization) is the process of using applying digital filters to deal with the unfavorable effects of a listening room’s acoustics and/or the speaker’s themselves. Usually the process involves use of a microphone, playing of test tones, measuring the audio, calculating a correction, and applying the correction. These “systems” work to apply improvements in the time domain and/or frequency domain. No amount of digital room correction can compensate for all of the acoustic problems in a room, at all listening positions.

Unbalanced Connector - An unbalanced cable consists of two connectors with two conductors each, connected by two wires inside the cable—a signal wire and a ground wire. Each wire has to terminate at the connector with its own contact point. They are not very good at suppressing noise from outside interference.

Headroom - The difference between the maximum dB signal being output (from the amplifier), versus the amplifier's maximum output.
Things to know:
Decibels are on a logarithmic scale.
Watts are on a linear scale.​
1dB represents the smallest human-detectable change in loudness. People perceive a 6-10dB increase in loudness as sounding twice as loud.
A 3dB increase in perceived loudness takes 2x the amplifier power.
A 6dB increase in perceived loudness takes 4x the amplifier power.
A 10dB increase in perceived loudness takes 10x the amplifier power.​
Let’s say you are listening at a volume you like, and for instance your amplifier is using 10 watts per channel to do this. (Many people enjoy music at 1 or 2 watts). And let’s say that the most your amplifier can output per channel (without distortion and/or clipping) is 40 watts per channel. If you were to increase the volume (from using 10 watts) until you are using 40 watts per channel, then you would output 6db more of loudness (perhaps twice as loud). Listening at the first volume (that is using 10 watts per channel), you have enough usable watts to double the sound loudness. You have 6db of Headroom.​

1,499 Posts
Discussion Starter · #4 · (Edited)
Things to know

These are found quotes that I think are important to know:

in the subwoofer frequency range, sub mid bass is centered around 80hz. That is where all the chest slam and impact comes from. Everything under 30hz is pressurizing, which give you that under water feeling.

Speakers and room treatments compose 90% of the sound you hear.
9% electronics.
1% wires.

So it is blatantly obvious where one should focus most of their money and time/effort. Where it counts... ;)

Get the best speakers you can, and best subs you can, the rest is all room treatments.

Even things like adding a thick rug to a hardwood floor, a bookshelf in the back of the room, and thick drapes over bare windows can make a different.
It doesn't have to be 4ft thick Nazi acoustic wedges and a straight jacket and cannibal muzzle and dolly. hehe ;)

Even with the best speakers, subs, amps and wires in the world, without room treatments you'll still be missing 20-45% of the system's max-potential because bare walls are one of the biggest contributors to distortion, succeeded only by clipping and bottoming out, or other such limits of the hardware itself.
From a puritan perspective, all wall/floor/ceiling reflections are nothing but distortion... now that is a blatant over-simplification, but it proves the point.
Some level of reflections are needed but only to make human ears "happy", as anechoic chambers sound like the way distilled water tastes, sterile of all life. Technically-accurate, but void of all possible life.

For the bass, a miniDSP is more-than capable of amending all but the worse bass-response problems. Of course having optimal subwoofer placement trumps EQ.

What works great for tweeters works horribly for subwoofers, what works great for subwoofers works horribly for tweeters. This often makes the room design and room treatments turn into a nightmare-ish ordeal; and of course such custom rooms are only possible in non-rented, dedicated-room builds, it is nearly impossible to get really-good sound in a normal living room or random basement/bedroom. But you can often get 85% of the way there with enough attention to detail and/or effort...

The next biggest improvement in my system was going with an Oppo 105 DAC/player directly to external amps, and scraping the idea of a AVR or SoundProcessor.
Nothing beats a direct unmolested signal IMO.
(But it's too late to go for that now, I would wait for the Oppo 115, as the 105 can't do Atmos or 4K discs.)

As for cables, unless they are lamp cords that have turned green, there is no need to upgrade beyond a fresh generic spool of wire like this:

As far as personal sound listening goes, few speakers below the $2000 range + $3000 worth of electronics will beat a Sennheiser HD800 headphone + headphone amp.
The only downside is that they still sound like headphones (sound directly on your ears), and it only works for a single person.
I'd rather have a set of HD800's than 80% of the systems out there.
Of course... if you need good sound broadcasted to more than 1 person, then obviously headphones just ain't gonna cut it!

1,499 Posts
Discussion Starter · #6 ·
MBM= mid bass MODULE MV= master volume

If you edit/fix your original post on these two I will delete mine.
Thank you for your knowledge. No need to delete your post.

Premium Member
278 Posts
LLT - Large Low Tuned

WAF - Wife Approval Factor

PR - Passive Radiator

GTG - Get To-Gether

Just a few I thought of thats not on the list.. Unless i missed em.

16,232 Posts
a few different interpretation of some acronyms
AVR: audio video receiver
DSP: digital signal processor
FR: front right speaker
MLP: meridian lossless packing (Meridian invented PCM)
Yep, agree on the AVR, had meant to mention that. DSP I shoulda included ing/or. MLP to me tho is My Listening Position but that doesn't really count anyways :)

LCR is left center right speaker

There is a whole big listing of the movie acronyms somewheres I used to know....ah, here it is.

6,642 Posts
What does it mean?
kind of an inside joke I posted shortly after I set up my Home Theater

If you haven't heard the words, you don't have enough subbage yet. :D
Better and more sensitive than a standard SPL (Sound Pressure Monitor)
and somewhat related to WAF.

...my Spousal Pissedoff Measurement goes off every time
my system has exceeded her tolerance levels...
Furniture, glassware and pictures rattling on the upper level (two storey home)
when I'm all the way down in the basement mancave playing with my toys makes her Lose it!

TTFSD !!! gets yelled down
the open stairwell all the way down to the basement mancave, and its LOUD!

I first heard it go off about 8 years ago, shortly after moving into our new home.
Right from day one I was told the main floor was off limits to my AV gear,
but I was free to do what ever I wanted in the unfinished basement.

...well even that changed the first time the TTFSD alarm went off.

you don't have to add it to your list, it's more of a joke ;)

1,499 Posts
Discussion Starter · #15 · (Edited)

That's not fair! I spent all night trying to figure out which bass-heavy movie that was.

I couldn't think of any real movie, so I invented "Teen Titans Fight Some Dude".
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9,900 Posts
MLP: meridian lossless packing (Meridian invented PCM)
Um, no they didn't. PCM. MLP =/= PCM.
PCM: Pulse Code Modulation, sometimes called Linear PCM or LPCM. Using CD as an example, a clock pulses 44100 times a second, and when it does the signal amplitude is recorded using one of 65536 levels per channel. (2^16, hence 16 bit).
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9,900 Posts
As you're talking about subs, then it's useful to know some of the T/S parameters.
T/S Parameters: A set of parameters that allow the mechanical operation of a speaker driver in various types of enclosures to be represented in electrical form. Named for Neville Thiele and Richard Small who did the pioneering work.
Sd: represents the cone area of a driver (think bore).
Xmax: Linear excursion of a driver (think stroke).
Vd: volume of air displaced by a driver at Xmax (Sd x Xmax). The volume of air displaced at a given frequency determines SPL.
HIL (Hoffman's Iron Law): Hoffman's Iron Law states that the efficiency of a woofer system is directly proportional to its cabinet volume and the cube of its cutoff frequency (the lowest frequency it can usefully reproduce). Put colloquially; small size, efficiency or low cut off frequency. Pick 2.
Xmech/Xlim: The point where further increasing excursion will cause physical damage to the driver.

Dunno if you wanted to include more technical stuff, but someone may get something out of it, or at least understand a bit more, especially if they're perhaps interested in coming over to the dark side (DIY). That should cover it for most people.

Edit: LPF: Low Pass Filter (correct above)
HPF: High Pass Filter.
BPF: Band Pass Filter
TH: Tapped Horn. A type of horn sub invented by Tom Danley.
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1,499 Posts
Discussion Starter · #19 ·
Call for more acronyms.
Call for explanations for the ??s

Premium Member
6,897 Posts
OB: Open Baffle
IB: Infinite Baffle
RMS: Root Mean Square
PEQ: Parametric Equalizer
CEA-2010: Standard Method of Measurement for Powered Subwoofers
XLR: Balanced Connector
RCA: Unbalanced Connector Introduced by Radio Corporation of America
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