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Post by patate91 on Sept 18, 2017 1:56:33 GMT
Please correct the me if I'm wrong.
I know that when played on an amplifier, each frequencies will have a different voltage reading at the output.
We can use this information with the speaker's impedance to get the power rating.
When music is being played more than one frequency will be played at the same, can someone explain me how the amplifier deals with that??
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Post by rock on Sept 18, 2017 2:44:07 GMT
1, A speaker's power rating has to do with how much power it can safely handle before it fails or is destroyed. Mainly this will have to do with how much heat the voice coil can handle before it is deformed or opens. I don't think a measurement of frequency and voltage will tell you anything about speaker power rating...unless you drive it into failure mode. Then you know how much it can't handle and you'll have a speaker that either needs repair or that can be tossed in the bin  2, I wondered about that before I studied electronics and I racked my brain trying to imagine all those instruments and sounds coming out of one (or two) speaker(s). It's really quite simple. All the frequencies are effectively added, summed or combined into one single complex signal which is a single complex waveform. Using an oscilloscope is a great way to demonstrate this. Cheers, Rock |
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Post by patate91 on Sept 18, 2017 13:04:54 GMT
1, A speaker's power rating has to do with how much power it can safely handle before it fails or is destroyed. Mainly this will have to do with how much heat the voice coil can handle before it is deformed or opens. I don't think a measurement of frequency and voltage will tell you anything about speaker power rating...unless you drive it into failure mode. Then you know how much it can't handle and you'll have a speaker that either needs repair or that can be tossed in the bin 2, I wondered about that before I studied electronics and I racked my brain trying to imagine all those instruments and sounds coming out of one (or two) speaker(s). It's really quite simple. All the frequencies are effectively added, summed or combined into one single complex signal which is a single complex waveform. Using an oscilloscope is a great way to demonstrate this. Cheers, Rock. For 1) I was refering to the amplifier power output. 2) Thanks, I'll try to get a grand on a friend's oscilloscope try experiment (Or buy one if I get a chance). Does it looks a little bit like this?  |
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Post by rock on Sept 18, 2017 13:40:50 GMT
1. OK, if you can measure the amp's output voltage and you know the the load resistance (for power measurement, I'd use a load resistor instead of a speaker) you can calculate the power: P=E squared / R www.sengpielaudio.com/calculator-ohm.htm2. Yeah, borrow your friend's but hold off on buying a scope if you're just going to do a demonstration. I'd suggest online tutorials. If you want to jump in the middle, here one I found that may help. www.youtube.com/watch?v=FrRmihdF52o3. A pure sine wave at a constant amplitude is what I would call simple, discrete, single frequency... anything else is compound or complex. Cheers, Rock |
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Post by patate91 on Sept 19, 2017 12:15:45 GMT
Another question.
Music in an electrical point of you is a complex waveform.
A source like my CD player will produce it.
My amplifier will, well amplify it.
Does it means that if I capture the waveform at a precise moment at my CD player's output and do the same thing at my amp's output at the exact same time I'll have the exact same complex waveform?
If the waveform is different does it mean one of the component in the chain is not "transparent"?
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Post by arnyk on Sept 21, 2017 13:22:14 GMT
Another question. Music in an electrical point of you is a complex waveform. A source like my CD player will produce it. My amplifier will, well amplify it. Does it means that if I capture the waveform at a precise moment at my CD player's output and do the same thing at my amp's output at the exact same time I'll have the exact same complex waveform? Yes, if the amp is good enough. Words like exact can get us into trouble. In the real world, things that are exactly alike are elusive. Now a days, measurement gear and analytical software are so good that there is always a difference, and it is the meaning of the difference that matters. In audio, terms like "Sonically indistinguishable" are much more to the point, practically speaking. No, because a sufficiently similar in shape, but far larger, smaller, or time-shifted form of the waveform is often considered to be a "transparent" copy. In reality, you can mangle a wave so that it looks horribly different in terms of measurements, and it sounds indistinguishably the same. Hearing only abstracts certain aspects of sound, and does quite a bit of mangling of its own. Hearing was apparently designed to help us survive, not be perfectionists. ;-) |
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Post by arnyk on Sept 21, 2017 13:32:35 GMT
Please correct the me if I'm wrong. I know that when played on an amplifier, each frequencies will have a different voltage reading at the output. True. No. Speaker power ratings are in reality complex. Obviously, the actual power rating would be like how much power the speaker can take without being damaged. But, its not even just that complicated, because how much power a speaker can take depends on many things: 1. The frequency of the signal. 2. Amount of time the signal is applied. 3. What happened to the speaker before the test, mostly how hot the speaker was from what went before. 4. Sometimes the design and size of the box it is in, especially for woofers. Then there is our mental model of the speaker, IOW do we treat it like it is a time-invariant resistor, or more like a real-world speaker whose electrical properties are always in some kind of state of flux depending the environment and recent history. Speaker voice coil resistance varies a lot, even 2:1 or more in non-destructive use. The voice coil resistance of a speaker can be measred while it is in use, and used to determine when it is approaching some common kinds of destruction. If the speaker and amp are designed to work together this can be done, and is even patented and implemented in some speakers. Ideally the amplifier treats multiple frequencies like each one is totally independent of the rest. This would be like zero Intermodulation distortion. Speakers are not very good about doing this well. Amps and digital players generally do a far better job. Vinyl playback is not that much better than speakers, sometimes maybe even a little worse. Analog tape at its best is not as good as amps, but better than most other things including speakers. However, abusing analog tape is actually an art that is proudly practiced by some. It used to be the best we had. |
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Post by patate91 on Sept 21, 2017 19:24:30 GMT
Ideally the amplifier treats multiple frequencies like each one is totally independent of the rest. This would be like zero Intermodulation distortion. Speakers are not very good about doing this well. Amps and digital players generally do a far better job. Vinyl playback is not that much better than speakers, sometimes maybe even a little worse. Analog tape at its best is not as good as amps, but better than most other things including speakers. However, abusing analog tape is actually an art that is proudly practiced by some. It used to be the best we had. I guess it would have been too easy  It's always interesting to read your post and anwsers. There's so much things I need to learn, but hey I'm not in a hurry! I'm having too much fun, especially with vintage gear. I'll use it more than one demonstration. I have an eye one those picoscope, but if I can find used and cheap I'll be more happy. www.picotech.com/products/oscilloscope |
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Post by rock on Sept 21, 2017 20:24:05 GMT
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Post by arnyk on Sept 22, 2017 11:55:49 GMT
My only working scope is a USB scope, and it has not impressed me. The problem with used scopes is that when they break, they are often either very expensive to fix, or fixing them is practically impossible. And their future life is unknown. That said, you can get some great old scopes this way, and the previous comments are probably the reason why. |
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