Originally posted by n9xv+Feb 21 2006, 09:13 PM--><div class='quotetop'>QUOTE(n9xv @ Feb 21 2006, 09:13 PM)</div><div class='quotemain'>What I am saying about impedance matching in regards to audio power amps is based on the indicated or published output impedance of the amp. If a high power amps manual says connect output to 2, 4, 8, or 16-ohms etc, then thats exactly what you should do if you want to acheive expected published results. If you connect the amp to a higher load impedance than that specified, you'll denie the amp of its potential to deliver the rated power. If you connect the amp to a lower load impedance than that specified, you'll be overworking the power supply in order to deliver the "extra" current to the lower load impedance. In other words, think of a "lab test" if you will. Take the high powered amp and run it full bore into its "specified" load impedance. Take the same amp, run it into a load impedance of half the specified value. The amp running into the lower load impedance will tend to clip the signal peaks due to the power supply not being able to support the designed MPP levels any longer. So we have distortion and increased heat dissipation and soon much damage will occur. Running the amp into a higher load impedance wont "hurt" it per say, the amp is just not reveiling its potential in that case. It cant deliver the "rated" power because the higher load impedance "limits" the available current to the speakers.
I'am trying to point out the facts about the importance of impedance matching but all I've seen as a rebutle is that the output impedance of an audio amp is very low so it does'nt matter what you connect to it. That wont "hold up" in the court of science.
When I say matched impedance, I mean "matched" to the specified output impedance of the amp in question. If an amp has a connection on the rear pannel labled 8-ohms, then one understands to connect an 8-ohm load to that output. The load is now "matched" to the output and the amp is happy. It does'nt matter what you "think" the output impedance of the amp "really" is, all that is necessary for the amp to operate properly is that it sees it's specified load impedance. Why do you think the impedance matching phenomena is different for AF than RF? It all boils down to efficiency. You can run power into a grossly mismatched load, and, as long as you keep it cool enough it will operate. The efficiency will be close to nothing but if kept "packed in dry ice" it will indeed operate. The designers knew what they were doing when they designed the amp. They gave it ratings based on certain criteria etc. For an audio amp that criteria is load impedance. To say an amp can deliver X-watts is only true if the amp is connected to the specified load impedance. If the load impedance is different than that specified, then X-watts is no longer true. Again I'am speaking of "real" power levels. This is true and applies to any power level but the "damage" is prominant at the higher power levels. I'am not arguing that 1 watt into a walkie-talkie speaker will destroy the amp if it is "mismatched" to the load.
Load impedance < the specified value = heavier burden on the power supply, increased heat dissipation, clipping/distortion etc.
Load impedance > the specified value = amp unable to deliver the available power to the load.
How much of a "problem" this all is depends on the power levels involved.
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So basically what you are saying is that for an audio amp the best scenario is to use a speaker with the "specified" impedance. And observing this "specified" load impedance is what you termed impedance matching?
<!--QuoteBegin-n9xv@Feb 21 2006, 09:13 PM
I'am trying to point out the facts about the importance of impedance matching but all I've seen as a rebutle is that the output impedance of an audio amp is very low so it does'nt matter what you connect to it. That wont "hold up" in the court of science.
[post=14256]Quoted post[/post]
[/quote]Please could you refer the scientific proof. I could always use something that broadens my limited knowledge.