Hehheh, I got a question

[Sparda]

Last time i brought up the question of what impedance meant when buying audio equipment and speakers/headphones, and i think i got the jyst of it, but it's time to ask the rest. When going over my sony catalouge of what to possibilly buy next i went across some terms i didn't understand, such as: THD (total harmonic distortion), SNR (signal to noise ratio). And remembered some terms from the past such as: Sensitivity and Impedance. All these technical terms boggle my mind! Would anybody be kind enough to help me on my quest of knowledge? Oh, and one more capacity!

- Sparda

[Tiesto]

I dont know much either, I took this from wikipedia:

Analog electrical

Total harmonic distortion (THD)

For high fidelity, this is usually expected to be < 1% for electronic devices; mechanical elements such as loudspeakers usually have higher levels. Nowadays very low distortion is easy to achieve in electronics with use of negative feedback, but the use of heavy feedback in this manner has been the topic of much controversy among audiophiles — for more on this see electronic amplifier. Loudspeakers typically produce more distortion than electronics, and 1–5% distortion is not unheard of at moderately loud listening levels. Human ears are less sensitive to distortion in the bass frequencies, and levels are usually expected to be under 10% at loud playback. Distortion which creates only even-order harmonics for a sine wave input is sometimes considered less bothersome than odd-order distortion.

Noise

The level of unwanted noise generated by the system itself, or by interference from external sources. Hum usually refers to noise only at power line frequencies (as opposed to broadband white noise), which is introduced through interference or inadequately regulated power supplies.

Dynamic range and Signal-to-noise ratio (SNR)

A measurement of the range of signal levels the device is capable of.

Dynamic range refers to the ratio of maximum to mimimum loudness in a given piece of music or programme, and this measurement quantifies the maximum dynamic range an audio system can carry. This is the ratio (usually expressed in dB) between the noise floor of the device with no signal and the maximum signal (usually a sine wave) that can be output without distortion.

Signal-to-noise ratio (SNR), however, is the ratio between the noise floor and an arbitrary reference level or alignment level. In "professional" recording equipment, this reference level is usually +4 dBu (IEC 60268-17), though sometimes 0 dBu (UK and Europe - EBU standard Alignment level). 'Test level', 'measurement level' and 'line-up level' mean different things, often leading to confusion. In "consumer" equipment no standard exists, though −10 dBV and −6 dBu are common.

Different media exhibit different amounts of noise and headroom. Though the values of course vary widely between units, typical analogue cassette might give 60 dB, a CD almost 100. Most modern amplifiers have >110 dB dynamic range, which approaches that of the human ear; 160 dB. See Programme levels.

[Sparda]

Yeah, the thing is i did go to wiki before asking, and i didn't fully understand it. Layman's terms would be nice.