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Still confused about clipping after reading all the articles.

From what I read, I understand what’s happening when the amp is clipping and the subsequent square wave form that could cause heat issues for voice coils. What I don’t understand is why would an amp allow itself to consume more power than it could handle in the first place.

1. More specifically, in the integrated amp scenario (amp with a volume control), let’s say you’re using a max power 80w integrated amp to drive a 87db@1w@1m speaker, if you turn up the volume on that amp, would it just max out at roughly the speaker playing 105db and it would not go louder - how could clipping happen then? Meaning the integrated amp should not throw a signal at itself stronger than it could handle?

2. For stand alone amp, I get that the input signal is not really under control of the amp and is more or less fed by the preamp so clipping could happen when the pre-amp is throwing big signals, but why wouldn’t the amp try to reject the signal the moment it senses clipping to protect the speaker?

3. Another related confusion is, how is it possible that sometimes I see powered active speakers blown because it’s trying to play too loud? Would it be true that the amp in those active speaker should always be designed to operate within the limit of its power handling? Could active speakers (say your Macbook speaker or iPhone speaker) enter clipping? I’ve never seen blown MacBook speakers even though people play at max volume all the time.

4. Could the source material itself be encoded to cause clipping? Let’s say a malicious sound mixer create a song with super quite music to force listener to turn the volume all the way up, but then there is a sudden loud noise encoded, would this push the amp into clipping?

5. Lastly, let’s say a speaker can handle 150w of power, and the speaker amp can output a maximum of 150w of power, even if the amp clips, does it mean it won’t damage the speaker? Could amp that’s rated at 150w per channel deliver much more than 150w in transient?

I might completely misunderstand some concepts here. But want to get some clarity.

bwang29

Showing 4 responses by cd318

cd318
2,636 posts
 
@rodman99999 ,

Good article. I was still a bit puzzled why clipping particularly tends to blow out tweeters.


'Since a clipped signal contains a high number of high frequency harmonics, tweeters are especially at risk for damage. These high frequency tones not present in the original signal are directly fed to the tweeter by the speaker’s crossover. The result can be a burned voice coil, i.e. permanent damage to your system.'
cd318
2,636 posts
 
@millercarbon,

Thanks.

That's the best explanation of this enormously complicated business I have yet read.

Only the other day my browser fed me this 'rant' from none other than John DeVore regarding misrepresented speaker sensitivity. 

I had to watch (listen to) it a few times before it made sense. OK, so I was at work doing something routine at the time...

-------

John DeVore goes on about the Hi- End Audio lie that inspired him to start his own company.

https://youtu.be/PEcFkSQMc8g


cd318
2,636 posts
 
@cakyol,

'It is ALWAYS safer to use a higher power amplifier on a speaker but ALWAYS MUCH MORE dangerous to use an amplifier which is under powered for a speaker, especially if the amplifier has no anti clip circuitry.'



Yes, that's been a key principle of mine during the past 30+ years.

My first serious amp, the now near legendary NAD 3020a had a feature they called 'soft clipping' as described in this link provided earlier by @rodman99999.

http://www.thefactoryaudio.com/blog/2017/1/28/soft-sabotage

I think I did eventually turn it off as suggested by the author William Crampton, but during the times it was left on you could actually hear the sound getting soft and rubbery if you turned the volume up too far past 12 O' Clock.

With an adequately powerful amp and reasonably efficient speakers the only thing to watch out for is sustained high volume levels which can burn out the voice through overheating. 

Thankfully that only happened once when my brother got carried away by blasting out some heavy metal that burned out one of the mid/bass drivers. It was cheap enough to get a replacement and never happened again.


Although the end result (driver damage) might be similar the causes are different.

Clipping, I believe, is caused by continuously overdriving the amp beyond its power reserves.

Overheating damage on the other hand is caused by the prolonged overdriving of the speakers. Too much power for too long.

A situation that's not likely to happen with modern speakers unless you wish to invite ear damage.

Both are dangerous but clipping is the more common risk of the two as even low efficiency speaker designs tend to have high power (heat) handling capabilities. 


@rego,

Good link. It's easy to forget just how magical the whole process of converting electrical signal into room filling sound is.
cd318
2,636 posts
 
@macbrett,

'These spikes only happen during clipping. The sharper the corner, the higher the spike.'



This has been a most instructive post. 

Thankfully I've never had issues with clipping, at least none that I was aware of or that left permanent damage.

It might yet be interesting to hear from those that have - if the memory is not too painful - just to see how common a problem this is.

I used to be so uptight about my system and if something ever went wrong it would upset me for a while.

I don't remember if it was just immaturity (lack of perspective) or the lack of money but it clearly wasn't worth getting into a hole over.

I can imagine owners of seriously expensive loudspeakers, and amps too, might want to make sure their chances of encountering damage caused by amplifier clipping it are kept to a minimum.
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