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Propeller Head Plaza Technical and scientific discussion of amps, cables and other topics. |
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Propeller Head Plaza Technical and scientific discussion of amps, cables and other topics. |
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In Reply to: Re: Here's what happens... posted by tomservo on August 19, 2006 at 20:49:04:
any discussion of the actual power dissipation in the amplifier output stage. Of course, the bias current and any power required to keep the output voltage where it 'should' be (according to the feedback loop and input signal) are dissipated in the output devices.However, as far as the speaker is concerned, the ideal feedback amplifier looks like a dead short (an ideal voltage source is modeled as a short-circuit to other sources in the network). If this is not the case, then the amplifier is deviating from ideal behavior. This means all the energy represented by the speaker's Back-EMF has to be dissipated in the speaker resistance.
This is an important point that many people overlook. The speaker must be designed to achieve optimum damping with a short-circuit across its terminals in order to work well with feedback amplifiers. This limits the motor strength in dynamic speakers, and is a major reason why we are stuck with so many large and wasteful amplifiers and miserably inefficient speakers.
See the link for an article published in 1954-5, that explains this in detail. This article is posted with permission.
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Follow Ups
- Attempting to be concise, I left out - Al Sekela 15:37:27 08/20/06 (0)
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