Electronics > Projects, Designs, and Technical Stuff
Yet another Audiophile Question.
robca:
--- Quote from: Bassman59 on August 07, 2020, 05:35:18 pm ---Again: area under the curve.
Your picture does show clipping and its effects, but it doesn't show units. Driver destruction is a function of heating. You can clip all you want, but as long as the total heat dissipated in the voice coil remains below "danger" levels, the driver is fine. For example, look at guitar amps -- their outputs are highly distorted but drivers don't die because generally the speakers installed are rated properly.
Remember that coil heating is integration. The driver might survive a minute of clipped inputs at/above its ratings, but will it survive the DJ night at your local club?
I think that for the low amplifier power levels relative to the rating of the drivers being discussed here, driver destruction is not a concern.
--- End quote ---
I didn't add units, but assume that the two signals are identical (same input, same amplification factor, same amplifier, just one with 12V power rail, another 24V. So the curves are identical, in the 12v case they are simply "lopped off" at 12V, in the other case can swing much higher). Just assume both graphs have the same curve, same units
The area under the curve of the clipped signal is much smaller than the area under the curve of the non-clipped one. So, much less power dumped into the tweeter (there might be a bit extra due to the crossover handling of the higher frequencies generated by the clipping, but still smaller than the more powerful aplifier)
I think we are saying the same thing: a low power amplifier even if with some clipping and distortion (and higher frequency harmonics dumping more energy into the tweeter) is unlikely to fry a tweeter that can handle 4x the continuous power. In the original question, the max power of the amplifier was 22W and used at half volume, and he speaker was rated 85/340W.
Can anyone here see a case where that low power amplifier would cause problems, for normal music (i.e. not signals designed to create problems)
JohnG:
A speaker rated for 85/340 W has some assumptions about the overall spectra of the input signal resembling that of music. If its all above the crossover point, and you put it all in the tweeter, you will blow the tweeter, your ears, or both, real fast, for the vast majority of tweeters. If the crossover has some attentuation of high frequency in the response curve, you may blow the crossover as well, although the tweeter will probably protect it. Clipping is a non-linear operation that will put a lot of power into the high frequency band.
John
robca:
--- Quote from: JohnG on August 07, 2020, 09:50:57 pm ---A speaker rated for 85/340 W has some assumptions about the overall spectra of the input signal resembling that of music. If its all above the crossover point, and you put it all in the tweeter, you will blow the tweeter, your ears, or both, real fast, for the vast majority of tweeters. If the crossover has some attentuation of high frequency in the response curve, you may blow the crossover as well, although the tweeter will probably protect it. Clipping is a non-linear operation that will put a lot of power into the high frequency band.
John
--- End quote ---
I understand that, but...
I built a couple of low power speakers (below 60W max) and looked at many designs before settling on one. Out of curiosity I looked at the specs of the tweeters used in those designs. Pretty much all tweeters I looked at could handle more than 40W continuous (only one specified the frequency as 6KHz, so definitely frequency can influence). The amplifier in the original question was 22W max. Even assuming that only high frequencies exist and the crossover is a perfect crossover sending all the power to the tweeter at the maximum amplifier power, there is sill a significant margin of safety
Now, granted, there are no specs for the LTS 1" tweeter used by the Klipsch speakers, and it's a horn loaded tweeter, so it's entirely possible it can't handle as much. But an 80W continuous speaker must be able to handle 80W of a 22KHz signal without too many problems. People routinely play speaker calibration CDs at high volumes, and those frequencies are common. And the max rating is still 340W, so there is a margin
I have a hard time understanding why, in this specific situation, using a 20W amplifier, even with clipping, can be a problem. "Area under the curve" doesn't explain it, nor higher harmonics. And, yes, clipping is non-linear and generates a ton of harmonics, but it won't generate a continuous 22W 40KHz signal dumping 100% of the power available into the tweeter.
In general, I understand perfectly how a poorly designed lower power amplifier might damage a tweeter. But I simply cannot see how in this specific scenario (22W amplifier of decent quality, hence low-ish clipping, 85/340W speaker) is a problem
DW1961:
--- Quote from: robca on August 08, 2020, 12:22:35 am ---
--- Quote from: JohnG on August 07, 2020, 09:50:57 pm ---A speaker rated for 85/340 W has some assumptions about the overall spectra of the input signal resembling that of music. If its all above the crossover point, and you put it all in the tweeter, you will blow the tweeter, your ears, or both, real fast, for the vast majority of tweeters. If the crossover has some attentuation of high frequency in the response curve, you may blow the crossover as well, although the tweeter will probably protect it. Clipping is a non-linear operation that will put a lot of power into the high frequency band.
John
--- End quote ---
I understand that, but...
I built a couple of low power speakers (below 60W max) and looked at many designs before settling on one. Out of curiosity I looked at the specs of the tweeters used in those designs. Pretty much all tweeters I looked at could handle more than 40W continuous (only one specified the frequency as 6KHz, so definitely frequency can influence). The amplifier in the original question was 22W max. Even assuming that only high frequencies exist and the crossover is a perfect crossover sending all the power to the tweeter at the maximum amplifier power, there is sill a significant margin of safety
Now, granted, there are no specs for the LTS 1" tweeter used by the Klipsch speakers, and it's a horn loaded tweeter, so it's entirely possible it can't handle as much. But an 80W continuous speaker must be able to handle 80W of a 22KHz signal without too many problems. People routinely play speaker calibration CDs at high volumes, and those frequencies are common. And the max rating is still 340W, so there is a margin
I have a hard time understanding why, in this specific situation, using a 20W amplifier, even with clipping, can be a problem. "Area under the curve" doesn't explain it, nor higher harmonics. And, yes, clipping is non-linear and generates a ton of harmonics, but it won't generate a continuous 22W 40KHz signal dumping 100% of the power available into the tweeter.
In general, I understand perfectly how a poorly designed lower power amplifier might damage a tweeter. But I simply cannot see how in this specific scenario (22W amplifier of decent quality, hence low-ish clipping, 85/340W speaker) is a problem
--- End quote ---
The watts for the TA 3116DD amp chip were about 2 x 24 watts at <.1% THD @ 19V.
Spec sheet:
https://www.ti.com/lit/ds/symlink/tpa3116d2.pdf?ts=1596921462063&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPA3116D2
Bassman59:
--- Quote from: robca on August 08, 2020, 12:22:35 am ---
In general, I understand perfectly how a poorly designed lower power amplifier might damage a tweeter. But I simply cannot see how in this specific scenario (22W amplifier of decent quality, hence low-ish clipping, 85/340W speaker) is a problem
--- End quote ---
In this specific scenario, the underpowered amplifier is not a problem.
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