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Rob J in WNY · 01-26-2009, 03:54 AM

One factor in the equation is that, with lower-powered amplifiers, there can be a greater danger of burning out speakers. Here's why.

Increasing sound volume is an increase in amplitude. In basic terms, audio output from an amplifier is an alternating current (A/C) signal. Think of a pure sine wave tone (which we will use for the sake of example). The "peaks" and "valleys" of the sine wave get taller as amplitude, or volume, rises.

With smaller amplifiers, continuously turning up the volume eventually causes the amplitude to hit its limit sooner than with larger amplifers. What then happens is that, with regard to our "sine wave" example, we actually cannot gain any further amplitude, so the peaks and valleys of the waveform cannot become any larger. Our sine wave is maxed out, and the peaks and valleys become "clipped" causing our smooth, A/C audio momentarily becomes a direct current (D/C) signal. When you hear of an amplifer being driven to "clipping," this is what is being referred to.

D/C voltage is particularly dangerous to the fine voice-coil structure in speaker drivers - especially tweeters. The coils overheat from the sustained D/C voltage, and their fine wire can either break (opening the speaker wire circuit) or else melt together, ruining the motive magnetic relationship with the magent structure. Usually accompanied by that burning smell!

While you can certainly "blow" speakers by applying too much "clean" power to them, smaller amplifiers driven too hard are a far larger danger. You can easily burn out 200 watt speakers with a 20 watt-per-channel amp driven to horrible "clipping" levels.

These are words to the wise. It's fun to drive our HTs to the max, but there is a danger in doing so, especially because there is almost always audio dynamics which seem to sneak up on us that will send an amplifer over the top. Know the limits and be careful with those (fun) demonstrations. As an example, with only a 6dB audible gain in perceived volume, and amplifer is demanded 4X the wattage. That's the difference between an average output of 50 watts to about 200 watts - many common HT receivers are rated for around 100 watts per channel, and peak program material, if sustained, will overtax an amplifier's "headroom" and cause voice-coil-threatening high-level D/C voltage.

Hope that helps!

01-26-2009, 03:54 AM	#2
Rob J in WNY Blu-ray Guru Member since:Dec 2008 Location:'Western' N.Y. State (MEMBER OF THE "ECPP")™ Home Theater Gallery:24 4K collection:30 Blu-ray collection:486 iTunes collection:1 Blu-ray reviews: 15	One factor in the equation is that, with lower-powered amplifiers, there can be a greater danger of burning out speakers. Here's why. Increasing sound volume is an increase in amplitude. In basic terms, audio output from an amplifier is an alternating current (A/C) signal. Think of a pure sine wave tone (which we will use for the sake of example). The "peaks" and "valleys" of the sine wave get taller as amplitude, or volume, rises. With smaller amplifiers, continuously turning up the volume eventually causes the amplitude to hit its limit sooner than with larger amplifers. What then happens is that, with regard to our "sine wave" example, we actually cannot gain any further amplitude, so the peaks and valleys of the waveform cannot become any larger. Our sine wave is maxed out, and the peaks and valleys become "clipped" causing our smooth, A/C audio momentarily becomes a direct current (D/C) signal. When you hear of an amplifer being driven to "clipping," this is what is being referred to. D/C voltage is particularly dangerous to the fine voice-coil structure in speaker drivers - especially tweeters. The coils overheat from the sustained D/C voltage, and their fine wire can either break (opening the speaker wire circuit) or else melt together, ruining the motive magnetic relationship with the magent structure. Usually accompanied by that burning smell! While you can certainly "blow" speakers by applying too much "clean" power to them, smaller amplifiers driven too hard are a far larger danger. You can easily burn out 200 watt speakers with a 20 watt-per-channel amp driven to horrible "clipping" levels. These are words to the wise. It's fun to drive our HTs to the max, but there is a danger in doing so, especially because there is almost always audio dynamics which seem to sneak up on us that will send an amplifer over the top. Know the limits and be careful with those (fun) demonstrations. As an example, with only a 6dB audible gain in perceived volume, and amplifer is demanded 4X the wattage. That's the difference between an average output of 50 watts to about 200 watts - many common HT receivers are rated for around 100 watts per channel, and peak program material, if sustained, will overtax an amplifier's "headroom" and cause voice-coil-threatening high-level D/C voltage. Hope that helps!