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Hemisphere
Old Croc Joined: 21 April 2008 Status: Offline Points: 2272 |
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"Now let's take some bullshit and present it as reality...and hey presto our argument holds water!"
Dub bassline = 3kw average power when peak draw is 6kw? How can you present this statement as fact? Hace you measured it? Did you even do the maths? A pure max amplitude sinewave with no breaks and no ASDR envelope (ie never happens in music as the ASDR gives the note punch)..is 1.5kw average power with 6kw peaks. 3kw average would be the same unlikely note driven 50% into clip and would sound unbearable. |
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Tonskulus
Registered User Joined: 15 September 2017 Location: Finland Status: Offline Points: 425 |
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Sorry i might be misunderstood here and that was propably bad example.. my bad :) My point was, if we push some amplifier to give 3kW RMS for speakers, it WILL take more than 3kW from the wall socket. It is just simple physics - power cannot be made out of nowhere as well as there is no free energy / power. This is what I was thinking. And for me, RMS power rating for amplifier means that it can push sinewave signal at claimed output power. That's the way I bench test my amplifier - using pure sinewave. I have designed and build dozens of amplifiers, tube and solidstate so I know how to do it. And it is not uncommon for music to have bass lines comparable to sinewave when it comes to power requirements. These are sometimes scary situations if DJ pushes amplifiers close to their limits, it makes lots of stress for voice coils too. What did you mean by average of 1.5kW and 6kW peak? Makes no sense if we talk about clean sinewave. Do you even know what sinewave signal is and how you calculate AC sinewave power? P=I*Urms. And for sinewave signal Urms (or average) = Upeak / sqrt2. Any better now I hope? :)
Edited by Tonskulus - 21 November 2017 at 11:58am |
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Hemisphere
Old Croc Joined: 21 April 2008 Status: Offline Points: 2272 |
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Unless I've fundamentally misunderstood the means by which a musical signal translates into power drawn by the amp (and I'm perfectly open to this being the case - the science you mentioned goes right over my head)...when the waveform is at it's maximum peak, (ie the top or bottom of the wave in a sinewave), that point represents full current draw from the mains. When at the midway point, no current is being drawn, and then there are gradations between those points. (Except obviously wizardry in various forms means the mains never actually sees that current draw in these new generations of amps).
When the waveform is clipped, the current sits at maximum amplitude for longer than the sub-millisecond point it would be there with a clean sinewave, and so at the maximum potential of an amp, the signal clips, because that's all it can do, it can't go any louder with each cycle so it just occupies more of each cycle with a maximum amplitude signal instead (or clip). We had this discussion a while back about Powersoft amps (and about a million other times by all accounts), and I did some close analysis of the waveform of a heavy dub track at it's apex, and it seemed to fit with what I expected based on the reasoning I just outlined, which I admit is not otherwise founded in a firm understanding of the underlying theory. If what you say about sinewaves is correct and my understanding is wrong then the Powersoft X Series on particular would be totally crippled for use on some music genres - they would crap out very audibly when pushed, except they don't, so there you go. Edited by Hemisphere - 21 November 2017 at 12:03pm |
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Tonskulus
Registered User Joined: 15 September 2017 Location: Finland Status: Offline Points: 425 |
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True that. And when signal starts clipping ie. sinewave is transforming to squarewave, RMS (or average) power increases also. Reason why voicecoils starts to suffer from overheating when signal is compressed and clipped. But anyway, i was talking about amplifiers input power versus output power - in theory, nothing less or more. And there the fact is, input is ALWAYS more than output in average. Music is not pure sinewave, or barely is.. So in common sense its not a huge problem having only 10A fuse in 230V outlet driving 5kW amplifier - unless we do some bench tests with sinewaves (I have blown some fuses with that) :D |
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Earplug
Old Croc Joined: 03 January 2012 Location: Europe Status: Offline Points: 7216 |
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Also remember that the PSU rail condensers are there to smooth out the bumps and help when there is a peak in the signal. So a sudden heavy bass line might not result in a sudden large rise in the current draw. The average power in will obviously be greater than power out, but only if integrated over time.
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Earplugs Are For Wimps!
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