This page states:
"This is essentially what is aimed for in stereo system design, where speaker impedance is matched to amplifier impedance for maximum sound power output. Impedance, the overall opposition to AC and DC current, is very similar to resistance, and must be equal between source and load for the greatest amount of power to be transferred to the load. A load impedance that is too high will result in low power output. A load impedance that is too low will not only result in low power output, but possibly overheating of the amplifier due to the power dissipated in its internal (Thevenin or Norton) impedance. "
This is total nonsense, and harks back to the claims of the "experts" as to why Edison's concept of electrical power distribution could never work. The "experts" assumed that for power transfer the load and source impedances had to be matched which meant half the power was lost at the generating plant. Edison designed a system with a low source impedance and constant voltage independent of load, so each load determined how much power to draw based on its load impedance.
In exactly the same way a power amplifier has a very low output impedance (small fraction of an ohm), and the loudspeaker impedance determines how much current and therefore power is drawn for a given amplifier output voltage. The ratio of nominal loudspeaker impedance to the output impedance of the power amplifier is called the damping factor, and for typical consumer and professional sound systems is in the range of 100 to 1000.
It is important to cover the Maximum Power Transfer Theorem, but please use a real example, not this one based on a faulty understanding of audio systems.
Ray A. Rayburn
Senior Consultant K2 Audio, LLC
Fellow of the Audio Engineering Society
Chairman of the AES Standards Subcommittee on Interconnections
Ray@SoundFirst.com
PS: This is the second time I have sent in a correction on this issue. It will be interesting to see if the correction is ignored again.
"This is essentially what is aimed for in stereo system design, where speaker impedance is matched to amplifier impedance for maximum sound power output. Impedance, the overall opposition to AC and DC current, is very similar to resistance, and must be equal between source and load for the greatest amount of power to be transferred to the load. A load impedance that is too high will result in low power output. A load impedance that is too low will not only result in low power output, but possibly overheating of the amplifier due to the power dissipated in its internal (Thevenin or Norton) impedance. "
This is total nonsense, and harks back to the claims of the "experts" as to why Edison's concept of electrical power distribution could never work. The "experts" assumed that for power transfer the load and source impedances had to be matched which meant half the power was lost at the generating plant. Edison designed a system with a low source impedance and constant voltage independent of load, so each load determined how much power to draw based on its load impedance.
In exactly the same way a power amplifier has a very low output impedance (small fraction of an ohm), and the loudspeaker impedance determines how much current and therefore power is drawn for a given amplifier output voltage. The ratio of nominal loudspeaker impedance to the output impedance of the power amplifier is called the damping factor, and for typical consumer and professional sound systems is in the range of 100 to 1000.
It is important to cover the Maximum Power Transfer Theorem, but please use a real example, not this one based on a faulty understanding of audio systems.
Ray A. Rayburn
Senior Consultant K2 Audio, LLC
Fellow of the Audio Engineering Society
Chairman of the AES Standards Subcommittee on Interconnections
Ray@SoundFirst.com
PS: This is the second time I have sent in a correction on this issue. It will be interesting to see if the correction is ignored again.