TIP # 25:
While talking with a friend and customer of ours recently, the subject of our Tips came up. He asked me for the meaning of a particular well used audio phrase, I did my best to define it for him. It struck me that the definition of many terms we use everyday, if not understood by others, can do little to address the underlying questions which motivate the use of such “tech talk”. Is it good or bad? Does it sound better or worse? Is it worth paying more or less?, etc. Since “Audio Jargon” is so ingrained in our everyday conversation we thought a short list of the more common terms and definitions might be useful:
Bi-Wiring: (Does not refer to a person’s sexual versatility) The ability of a loudspeaker to accept two sets of cables from an amplifier (or occasionally vice versa). One set is for the high frequency unit(s), the other set for the low. This increases dynamic range by preventing current fluctuations caused by power demands from the woofer.
Class A: (Does not mean “Canadian made”) Refers to the way current flows in an amplifier. Two output devices supply continuous current for the duration of a signal. Requires premium components (increases cost), creates heat as the amp runs at 100% output continuously, eliminates output switching noise making for smoother sound.
Class B: As above, except each output operates for half the cycle time, while the other output is switched off. Less expensive, low heat output, can introduce audible switching distortion.
Class A/B: Current flows through each device for more than half the cycle time, while the other output is switched off for less than half the time. Best value in “sound dollars”. Some heat, low switching noise, not expensive to produce.
Current: Tasty morsel, measured in Amperes to denote the amount of electricity flowing along/through a conductive material. Used to describe an amplifier’s ability to deliver power to a speaker. More is better, but also more money.
dB: Symbol for decibel (deci or 1/10th, and Bel the scale for volume measurement, as in that Alex Graham guy). A unit denoting sound volume. Somewhere between one and three of these units lurks the smallest volume increment variation discernible to the human ear.
D to A: Digital to Analog converter. Every CD player has at least one (good to know, eh!) It takes the digital information from the CD and converts it into an analog wave, which can then be amplified and reproduced by speakers. Many different types, each with merits.
Dolby Pro-Logic: The Dolby laboratories consumer version of their surround processing designed originally for use in movie theatres.
Dynamic Range: The distance in dB between the loudest and the quietest passage of sound, at a set volume level.
Dynamic Headroom: (Does not refer to extroverts) The difference (in dB), between an amplifier’s continuous output capability and it’s ability to reproduce a quick change in volume at peak output. Once the holy grail of amps, some will now say it shows a potential for a poor power supply, which can veil the image.
Frequency: (No comment) A sound wave. The faster the frequency the higher the sound, the slower the frequency the lower the sound.
Image: The realistic “Mirage” or sense of the recorded performance occurring between, behind and around the loudspeakers.
Mirage: A speaker that images (just testing to see if you’re still there!)
Oversampling: (Does not have anything to do with beverages) Refers to the frequency of a CD player’s D to A while playing a disc. The number of times above the original recording’s sampling rate indicates a faster processor. A benefit here is getting the sound generated by the sampling clock, high enough to prevent interference with the music, allowing us more choice for other components in the output stream. This should not be a deciding spec in choosing your next CD player (too many external variables).
Watts: (Often used by those who do not understand Audio Jargon) Describes an amplifier’s output to the loudspeaker. A swing gate, meaning the combination of several specifications (voltage and current) to arrive at one value. More voltage and less current or less voltage and more current can result in similar numbers. The music playing ability of similar rated amplifiers, can vary dramatically. The result of all this is that the wattage output number is of dubious benefit when comparing amplifiers of different manufactures, who likely employ differing measuring procedures.
Sense: (Sometimes found at K&W Audio) The ability to step back from clutter and confusion, without losing sight of an underlying goal, when buying an audio/video component, i.e. Does it do what I want, sound good, work well, play loud enough, heat the house, or get me evicted. Specs are wonderful things for the technically minded but if one is not careful one can end up on the slippery slope of listening to a system of component specs rather than simply enjoying a good tune or movie. In the final analysis, trust your ears. Don’t lose sight of the real reason you have to have a High Current, 220 watt, class A/B, Bi-wireable amp with 6 dB of dynamic headroom. Because it’s cool, of course, of course!