Distortion Confusion? Where does it come from?


I know a little about the THD of receivers, and I am aware that around .05-.06 is pretty good. But Im confused on how distortion of sound is played out. I originally thought it was the ineffiency of the speakers that caused the distortion , but the more I learn about the home audio world Im thinking it sounds more like the receiver is at fault..... So which part of a HT system bares more burden of responsiblity of distortion, the receiver, or the speaker, maybe both??? Someone please help

And is a THD distortion on a receiver of .07, mean that it not such a good receiver, what is a good number to stay around? I saw a Rotel at around .05, some H/Ks rated that too.

There are many forms of distortion. We'll stick with THD for now.

Total Harmonic Distortion consists of sounds that are ADDED to a signal to a sound that is not part of the original source and is a mathematical multiple (a harmonic) of a source's sound.

As an example a 1KHz tone played through a piece of audio equipment (any audio equipment) may produce a very low-level 2KHz tone also due to stability, low damping, ringing etc. That 2KHz tone is the 1st harmonic. Further there may be another tone (usually lower in volume) at 3KHz. This is the second harmonic. There will be other low-level tones at 1KHz intervals up until an agreed upon stop frequency -- usually 20KHz. If you add their levels up and figured the total level relative to the original tone (1KHz), that is the Total Harmonic Distortion. Since THD produces higher tones it sounds to you as a shrill screatch and will quickly wear you out and cause you to turn things down.

Most analog equipment produces higher distortion as level goes up. Amps and digital equipment produce LESS distortion as level goes up and then suddenly completely loose there composure (near 100% distortion at only 6db above rated 0db) as they clip.

Speakers, by far, produce the most harmonic distortion in your system. Staying below 1% THD is unusual at as little as 10 watts -- especially in the bass. For the most part, any THD rating under 1% is unlikely to be audible by most people. I wouldn't sweat a .07 and a .05 amps THD rating.

Hope this helps.
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