Quote:
Originally Posted by amitk26 ... How is it throughput the range ? ... |
(I assume by "throughout the range" you meant "at all frequencies") Clipping is frequency-independent, i.e. no matter which frequency or combination of frequencies the signal envelop has (what one can see on an oscilloscope, or what the ear hears), clipping is saturation of amplification at output. Saturation is that state that the amp cannot amplify the signal any further, and the output voltage stays constant for the period that this happens.
This period is actually very short (only peaks exceeding supply voltage are clipped), and since the transition from normal envelop to saturation is a step (not smooth), this appears as a quasi-square wave at the output. As you mentioned, the harmonics in this unnatural square wave are what you hear as distortion superimposed on music. The whole music does not distort, only the sources whose peaks have clipped. Unfortunately the whole music experience then actually sounds terrible to us!
Quote:
Originally Posted by amitk26 ... Suppose the speaker is being fed with an amplifier ( external or output stage of HU) such that amplification level is lower then rated capacity of speaker.
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won't these harmonics distroy the speaker diaphram ? |
LOL You are confusing yourself by not considering all the Use Cases!
1. Some speakers mention Power rating as, e.g., 8-120W. Why? 8 watts in this case is the minimum power required to produce music at normal audible levels (not requiring us to take our ear to the speaker
). If this figure were to be, say, 16W, it would be unsuitable for driving from the HU (internal amp about 14W rms). This minimum power is most of the time indirectly inferred from the sensitivity figure (lower dB = less actual loudness for the same power)
2. "Rated capacity" of a speaker (120W in the above case) is an average power level which the speaker can be played at continuously for hours without failing. "Maximum Power" is the power which if actually sent through the speaker is likely to fry the voice coil. Neither of these are *absolute* figures, since actual usage with associated air flows and thermal conditions may or may not cause the Rated or Maximum condition to be reached
3. What power *actually* flows through the speaker at any given moment is rather very difficult to calculate - it varies with music. Look at it this way: if one takes FFT of a piece of music with 256 discrete components (most common), the summation of electrical power corresponding to each of these components is the actual power flowing into the speaker. Even this is a mathematical approximation (256 discrete samples, not all of the signal). By this you should realize that saying "feed rated power into the speaker" is not a very logical thing to say
4. Your expectation of harmonics is very correct. However, you should realize that the harmonics are as much valid frequencies as any music. ONLY a human brain differentiates between music and noise, relying on previous learning and experience. How else would we differentiate between intentionally introduced guitar distortion, and incidental clipping at the amplifier while reproducing the signal???
Will the artificially produced harmonics deteriorate any speaker component? NO! But ...
5. It is the 'square wave', or more precisely the step transition in power which is the difficult thing. A discrete step, as opposed to a smooth signal, especially at high power levels, induces very high acceleration in the moving parts. This 'jerk' can cause joints (VC, spider, cone, surround) and material faults (in cone and spider) to gradually / ultimately fail. Very similar to sports injuries like shoulder dislocation in 'throwing' sports
Whether <, = or >, the relationship is more a matter of getting the
right amp rather than simple numerical matching. A comparatively terribly underpowered amp may sound really good, and a numerically matched one absolutely hopeless. My decision-making is simple: I never intend to fry voice-coils, which is a distinct possibility if Amp power >= Speaker rated power.