Originally Posted by Remeniz
What a load of faff!
I know about Ohms law and dont have to refer to a calculator on line.
Your case description is so extreme only a fool would try that. But there's always one I guess...
Clipping is one type of distortion that an overdriven amp will produce. If you study basic electronics and technology you'll realise that an over driven amp will also produce many more harmonics and phase distortion to name a few. Look these up and see what these can do to high powered speakers! And also study how an amp does it's work. Square waves anyone?? I don't think so.
I mean calling my explanation 'bollocks' is what i'd expect especially after your ridiculous practical explanation you gave.
Some of the 'stuff' you have said is fine. But you contradict your opening comment by most of your post.
Anyways go with who you wish. I will go on the advice and practical evidence recieved from teachers and producers alike.
first, I have studied electronics, firstly at GCSE Level, secondly at A level and thirdly at degree level,
I've been making speakers, and amplifiers as a hobby for the past 11 years,
Anyway, you may be aware of ohms law, but you seem to ignore that it applies?
you say get am amp that's bigger than the speakers. and there will be no trouble?
I'll admit that my example is extreme (100W amp 3W speakers), but it was meant to be extreme to show what you'd said was such bollocks,
or are you now revising your statement...
as far as I read it was that the rule
is that your amp has to be higher powered than your speakers are rated at else you're likely to overdrive the amp and make the amplifier clip and distort and that'd damage much higher power speakers, (though surely if that were the case it's damage lower powered speakers as well exactly the same)?
you can never
go wrong yet I pointed out that you can go wrong. with this... (yet a brief example involving just the smallest about of actual scientific theory prooves what you said wrong)
going back to the calculator, take a less extreme example, use 75W spakers with a 100W amp.
when your amp is cranked up full there is 3.5 amps running through the voice coil, yet the speaker can only handle 3 amps, as it's rated at 75W, and it can't handle that continuously either, that's a 14% overload over what the speaker can handle.
the voice coil will deteriorate over time.
As for the rest of my post.
Yes, I pointed out that if you have 75W speakers you can use a 100W amp and not break the speaker assuming that you don't turn it up all the way...
in which case, what's the point in spending extra on a larger amp?
i.e your example can work, but only if you waste a lot of the capacity of your amp.
and yes, clipping, like a square wave. try looking at the output of a amplifier that's clipping with an oscilloscope,
in fact this image descripes better than I ever could with words
now here comes the scientific fact part again, listen carefully I know you had trouble with that the first time.
look at the wave form, you see in the first example the part where the waveform reaches around a quarter of the way to the top is about a quarter of the way into the graph...
yet the second waveform shows that the the wave reaches half way to the supply voltage (where it clips) in about an 1/8 of the time taken to complete a half cycle.
The point is, (and this is where it gets really obvious), that higher voltage is on for longer, the current flows at a higher value for longer, more power is coming out for a longer time. and thus since there is power on for a greater period of the cycle of the wave the speaker coil is generating heat for a longer period, which is harder to disipate, and the energy builds up until it's rather hot and the speaker coil can melt.
you talk about harmonics introduced, but do you have any idea how you can make a square type wave? square type waves contain almost infinite higher frequency sine waves, so what you're saying (in your second post where you tried to get technical) and what I'm saying (in my first and second post) is essentially the same thing, clipping produces a square type looking wave, you'll see it in the diagram above. and that waveform contains a large amount of harmonics that actually go into making a square type wave form.
however, you're still wrong.
Sure, clipping is
producing extra harmonics but they never approach the levels of the amplified high frequency source signals.
what's that? oh just some guys research paper that shows what you think that you've been taught, is (as I said) bollocks.
So lets sum up.
you get an amp that's too small, you over drive it you'll break even high powered speakers,
so the best thing that you can think to do is get an even higher powered amp, even though you surely must realise that you can't turn it all the way up without damaging the speakers that you have.
having said that, I'm giving up now.
you made a statement said that it was a rule, when proved that your 'rule' was not a rule and was just blatantly wrong you sit there moaning about how you can't be wrong and you'd rather believe advice of producers, what producers? what teachers, can you even link to anything to show what you said is a fact?
or do we just take your word for it, against the odds of common sense, basic examples, and now scientific research papers...