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*  Price: Even at Overstock.com, you can spend a lot of money on audio video accessories (we know, it’s hard to believe, but it is possible). You can buy a discount car audio system (but never cheap car audio) or a very inexpensive home theater system, or you can go for broke (but never go broke) with a 6-foot wide HDTV plugged into 6-foot tall tower speakers. Before you begin, decide how much you’re willing to spend; then pick the components that fit your budget.

* Location: The portable radio has almost, but not entirely, been replaced by portable CD players, iPods, MP3 players and even DVD players. You might think these wouldn’t work in a home stereo. Actually, an iPod or MP3 player makes a great core component in a mini stereo system, and even a small DVD or CD player can run a big home theater, so you can save money by integrating mobile and home stereos. This is also true of car stereos and mobile video; many have plug-ins that connect to other types of components. If you’re looking to build a major home theater system, plan carefully to get the most appropriate audio equipment. A 10-ft. x 10-ft. room doesn’t need the same audio system as a 15-ft. x 20-ft. room, and you should consider the factors that don’t seem to matter: Does the room have large doors or open walls? Where are the electrical outlets and cable hook-ups? How is the room’s traffic flow? You don’t have to buy it all at once (although, if you insist, we’ll sell it to you all at once and save you a mint on shipping!), so if you have a plan, you can get better home audio equipment at better prices.

* Connection: Audio cables come in an amazing variety to deal with the amazing variety of components. Some are just bare wires; others are gold-plated and designed for specific types of components. Make sure you plug the right audio cables into each audio accessory. If you don’t have the right cables, you’ll need to buy adapters. Good cables and adapters are relatively inexpensive. The best are not cheap, but they do provide superior signal transfer.

* Options: Now that you have an audio system in mind, make a list of the audio equipment that fits your budget and rank the features: Number of speakers? Floor, bookshelf or wall mounted? Does it need to fit into an entertainment center? (You don’t have an entertainment center? You should visit Overstock.com’s furniture store.) The more questions you ask, the more you’ll know exactly what to buy.

Volume is measured in decibels (dB) and gauges both air pressure and sound volume. Think “How hard do I have to hit the drum to make a noise that loud?” In theory, 0dB is the threshold of hearing, the softest sounds people can hear, though many individuals are higher or lower. Ears don’t respond to all frequencies equally. The high and low ends of the scale need more volume to sound like they are the same volume as midrange frequencies (see “Equalizer” below). Loud sounds can, of course, damage your hearing, and hearing loss is usually permanent. Avoid anything over 90dB (jackhammers, airplane engines, H-bombs going off) and do what your parents kept telling you to do when you were a teenager — turn your stereo down!

In theory, the response should be steady. That is, 20Hz at 10dB should be as loud as 20KHz at 10dB, but perfection is still a few years off, so you may see “20Hz-20KHz +-3dB” meaning frequency response will vary by 3dB across the range. The better speaker will have a wider frequency response with lower variance.

Impedance exists because wires and microchips are solid objects that impede (ever so slightly) the flow of electricity. Think of a water pump connected to two pipes — the larger pipe has lower impedance because more water can flow through. Impedance is measured in ohms (abbreviated by omega, the horseshoe-shaped Greek letter). Stereo amplifiers and speakers are usually rated at 4, 8 or 16Ohms; they work best when the numbers match; mismatched components can give you bad sound or damage each other.

*  1MB = 1,000,000 bytes
* 1GB = 1,000MB
* A typical 1GB iPod or MP3 player can store 200-300 songs (depending on play length).
* A standard CD is 750MB (about 75 minutes of music).
* A standard DVD is 4.7GB (just over 2 hours of video).
* DVRs record onto a hard drive instead of disc or tape; its capacity will be measured in GB — many, many GB!

Power is the amount of electrical energy each speaker can use before exploding (okay, before being damaged). Measured in watts (W), it varies with the size of the system and may carry two numbers: normal and maximum power (maximum is almost always twice normal). A speaker rated 75W normal usage would be marked “75W RMS/150W peak power” or “75W continuous/150W peak”(RMS = ‘root-mean-square’, a meaningless phrase unless you’re an engineer). Cranking up the volume puts more energy through the speaker, causing more wear on the components. Think of wind — your house might survive a steady 75-mph wind (your basic hurricane) for several hours, but it’s much less likely to hold up against 150-mph gusts (Katrina revisited). Some people think there’s no such thing as too much power; these are people who regularly buy new speakers and hearing aids.

Sensitivity measures speaker efficiency, or how much volume a speaker puts out for a given voltage. There is no universal standard, so for simplicity, if speaker A’s sensitivity is rated 3dB higher than speaker B’s, then A needs less juice to put out the same volume as B. Higher sensitivity means a lower electrical bill, if one may put it so.

Signal-to-noise ratio (SNR or S/N) is about clarity. “Signal” is the sound you want to hear; “noise” is the unavoidable audio clutter in the background. Usually measured in decibels (dB), the higher the ratio, the less noticeable the clutter.

Surround sound describes a suite of speakers identified by a number: 5.1-channel, 6.1-channel or 7.1-channel. The “.1″ is the subwoofer. The other numbers define how many speakers are in the set — 5-channel has a center speaker, left & right speakers and left & right surround speakers. 6-channel adds a single rear surround speaker and 7-channel adds two rear surround speakers.

Total Harmonic Distortion (THD) is similar to SNR. Imagine an amplifier as a copier set to enlarge; it won’t make a perfect copy. These imperfections are ‘distortion.’ THD is expressed as the percentage of distortion within the total sound. A good audio component has a THD around 1-percent; really good audio components are below 0.1-percent.
Audio components

Amplifiers and pre-amps

Basically, every device that makes sound has an amplifier. Modern microphones are very small and use a tiny amount of electricity, which, if recorded without an amplifier, would reproduce as a whisper. Still thinking of an amplifier as a copier set to enlarge? Imagine using two copiers. The first is the pre-amp. If a recording has very low signal or a lot of distortion, a preamp can strengthen and clean up the signal, then the amplifier will power it up to speaker level.

8-tracks, cassette decks and turntables

No joke here; many people still have audio cassettes and vinyl disks, many are becoming collectors’ items, so don’t throw away those ‘manhole covers’; take a walk down memory lane with the original analogue tracks.

Tags: audio accessory, audio video accessories, car audio system, car stereos, cheap car audio, core component, GPS News, home stereos, hook ups, mini stereo system, portable radio

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