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<blockquote data-quote="bubbagumper6" data-source="post: 8271899" data-attributes="member: 567719"><p>I don't believe you have a clear understanding of what 'rail voltage' actually means and you're confusing it with output voltage. The internal rail voltages should not fluctuate (to my knowledge). In a standard PWM output section the amplifier has both a positive and negative rails, say they're 70V just for example. So one is +70VDC and the other is -70VDC. The input signal (AC) is used to drive transistors open and closed on each rail to cause the output voltage to swing from rail to rail, this is what creates your output AC waveform (after a lot of filtering). The control circuit has no control over how large of a signal it tries to produce, so if you try to produce a waveform that peaks higher that 70V (or lower than -70V) the output voltage will stop rising once it hits the rail voltage (because you cannot create voltage from nothing) which causes the peak or valley to flatten as basically pure DC.</p><p></p><p>If you're increasing the impedance, the output current should decrease. Less current means less stress on the components, not more.</p><p></p><p>As I said before, impedance is NOT CONSTANT. A '1 ohm load' is very rarely actually a 1 ohm load on the amplifier. See how the speaker is only actually 8 ohms around a very small frequency band?</p><p></p><p><img src="http://www.amplifiedparts.com/sites/default/files/imagecache/tech_corner/sites/all/modules/custom/tech_corner/images/speaker1.png" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p></blockquote><p></p>
[QUOTE="bubbagumper6, post: 8271899, member: 567719"] I don't believe you have a clear understanding of what 'rail voltage' actually means and you're confusing it with output voltage. The internal rail voltages should not fluctuate (to my knowledge). In a standard PWM output section the amplifier has both a positive and negative rails, say they're 70V just for example. So one is +70VDC and the other is -70VDC. The input signal (AC) is used to drive transistors open and closed on each rail to cause the output voltage to swing from rail to rail, this is what creates your output AC waveform (after a lot of filtering). The control circuit has no control over how large of a signal it tries to produce, so if you try to produce a waveform that peaks higher that 70V (or lower than -70V) the output voltage will stop rising once it hits the rail voltage (because you cannot create voltage from nothing) which causes the peak or valley to flatten as basically pure DC. If you're increasing the impedance, the output current should decrease. Less current means less stress on the components, not more. As I said before, impedance is NOT CONSTANT. A '1 ohm load' is very rarely actually a 1 ohm load on the amplifier. See how the speaker is only actually 8 ohms around a very small frequency band? [IMG]http://www.amplifiedparts.com/sites/default/files/imagecache/tech_corner/sites/all/modules/custom/tech_corner/images/speaker1.png[/IMG] [/QUOTE]
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