Electronics > Projects, Designs, and Technical Stuff
Yet another Audiophile Question.
helius:
--- Quote from: robca on August 06, 2020, 09:21:02 pm ---Is recovery from clipping that slow? Or am I missing something else?
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In your second (clipped) waveform, the shape approximates a square wave, which as you know has odd harmonics up to very high frequencies.
In a typical two- or three-way loudspeaker, the crossovers provide a high-pass filter for the signal going to the tweeter; but there is no high-cut filter, so ultrasonic frequencies go to it as well. They do not go to the other drivers.
David Hess:
--- Quote from: jh15 on August 05, 2020, 05:49:58 am ---Back in the 70's hifi days 40 watt amps were good at blowing tweeters. Klipsch is saying a low powered amp could blow theirs while clipping. Likely they put a ballpark figure to not blast/play loud them with less than a 60w amp.
And worded not well with some tech support offshore rep.
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I think that is exactly the situation. The third harmonic distortion from a *lower* power amplifier driven into clipping can damage the high frequency speaker because it is producing high frequency content that did not exist and twitters specifically have low power handling capability.
The representative missed the implications of limiting distortion to 1%.
--- Quote from: robca on August 07, 2020, 12:19:54 am ---
--- Quote from: Conrad Hoffman on August 06, 2020, 11:24:19 pm ---As usual, Rod Elliott explains things better than I ever could- https://sound-au.com/tweeters.htm
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Relevant part here:
A persistent myth in the audio industry is that clipping damages tweeters, so you should use a bigger amp to ensure more headroom so the amp won't clip. This claim is simply bollocks! Take the 100W amp described above, and replace with an amp big enough to prevent clipping ... even with the additional 12dB input signal as shown in Figure 7. Since a 100W amp was just below clipping with an average output of 16W, if we add 12dB that takes the peak amp power to 1.6kW (near enough) and the average power will be 254W.
Do you imagine for an instant that this amp won't blow the tweeters (and everything else) if the input level is increased by 12dB (until it's just below clipping)? Everything will fail, and usually fairly quickly if the speaker was designed for a 'nominal' 100W input. It is simply nonsense to imagine that the loudspeaker drivers in a 100W speaker can survive an average power of over 250W and peak power of up to 1.6kW.
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But the situation he describes is not realistic. One might turn a lower power amplifier up causing clipping but a higher power amplifier would not have been turned up to full power in the first place because it would already have been loud enough. If I need 20 watts of low and midrange for comfortable listening, and use a 10 watt amplifier, then I turn it up past the clipping level generating more high frequency distortion while a 40 (or 20) watt amplifier turned to 20 watts produces practically none.
DW1961:
Another interesting fact about the 3116D class D amp is that it's distortion is 10% max.
If you look at my graphic above and the sound level, it's so loud at 1% THD that it would never need to be louder, and that's at 50% power at 19V. If I pushed it to max power and THD 10%, at 19V, I could get 95dB out of it at 10'.
Isn't 95dB at 10% THD considered pretty decent?
The point is that even if I push it to max at 19V, the dBs don't change. (24 watts to 28 watts)
At 10'.
More interesting is that:
if I push the watts up from 19V at 1% THD: 23 watts = 94Db
if I push the watts up from 24V at 1% THD: 33 watts = 96Db
TimFox:
What is the basis for your statement that 10% distortion is “pretty decent”? When I measured distortion on my amplifiers, 10% THD was found when the amplifier was noticeably clipping on a CRO.
DW1961:
--- Quote from: TimFox on August 07, 2020, 02:41:50 am ---What is the basis for your statement that 10% distortion is “pretty decent”? When I measured distortion on my amplifiers, 10% THD was found when the amplifier was noticeably clipping on a CRO.
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Hey Tim,
10% measured at full amp power. If think the 3116D is 10% at full power, whatever that is for voltage up to 26V. It's less than .1% at 50% power, and I don't know what the increase is for each step above 50%. So, it might not even clip at 10%. Spec Sheet:
https://www.ti.com/lit/ds/symlink/tpa3116d2.pdf?ts=1596787799909&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPA3116D2
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