after some quick research i found a great article on the subject
Linear Scale 0 1 2 3 4 5 6 7 8 9 10 (+1) Logarithmic Scale 1 2 4 8 16 32 64 128 256 512 1024 (x2)
The non-linearities of the Human Ear
Linear Scale 0 1 2 3 4 5 6 7 8 9 10 (+1) Logarithmic Scale 1 2 4 8 16 32 64 128 256 512 1024 (x2)
The non-linearities of the Human Ear
Well found, Gaz!
You'll have gathered that it is more correct to say that hearing is logarithmic rather than say that the ear is logarithmic. 😎
You'll have gathered that it is more correct to say that hearing is logarithmic rather than say that the ear is logarithmic. 😎
I am not as scientifically savvy as you guys but maybe the ear is not only factor in your equation. Maybe somebody who knows what they're talking about can clear things up.
Sound is a pressure wave. Air has a mass.
To double the speed of a car you need 8x the power. (Scarily close to the 10x the power required to double a volume).
Back in my live mixing days I came across a guitarist with an AC30 who made the drummer and PA (EV 15/3s) inaudible.
Since he refused to turn it down because he'd 'be losing tone' we had to aim it towards the toilets behind the stage.
Some people tried to use the facilities during his band's performance, none succeeded. The bass player ripped a few strings trying to keep up.
@Galu hi galu hope your well in these crazy times.
some might say your splitting hairs, but i get your point. 🙂
some might say your splitting hairs, but i get your point. 🙂
@ Gaz
Thanks - I'm even crazier in these crazy times!
Nowadays I spend a lot of my time plucking hairs from my ears - just one of the joys of growing old!
Thanks - I'm even crazier in these crazy times!
Nowadays I spend a lot of my time plucking hairs from my ears - just one of the joys of growing old!
To calculate the required power at double volume, you either need to search for readily derived formulae or do the derivation yourself.Surtsey said:
A derivation like this requires first to draw a neat and clear diagram with all variables clearly defined. Probably, you will also need thermodynamics as applied to gas molecules. You will have the random motion of air molecules, which is already accounted for by thermodynamics, and the added motion components from the sound wave.
This is simply too much to process in the head without knowledge of some previously derived formula: the maths is far too much to handle in ones head within the span of a few seconds.
Memories of old days 🙂
Notice we are talking **30W** , 4 x EL84 amps here! 😱
Anybody talking 200/300W (PMPO or whatever) or more on stage will be fit inside a straitjacket.
Most UNBEARABLE amp I ever witnessed was a Dual Showmn driven balls to the wall into a 2 x EVM15L cabinet (instead of the usual JBL D130) .
Same as you remember, we first covered cabinet front with old carpets available at the theater, then had to turn cabinet backwards, no doubt crumbling some wall paint in the process 😛
Audio is peaky, all crest-factor. Most peaks can be covered by supply caps and hardly blip the utility power meter.
Crest factor for speech/music under brutal distortion may be 6dB; for clean reproduction always over 16dB.
5/7/13-channel amps are not rated like lab-shaker amps; it is unlikely that ALL channels will pump FULL power at the same time. And not normally distorted. Taking 166W+333W+333W= 800 Watts and conservative 12dB crest factor means 75W input can support 1000W of DC and 800W of audio.
A sub-woofie may be driven to distortion, but not continuously (thump-a-thump, not boooooooom). A woofer voice-coil will not melt in one thump (and modern drivers will survive huge short-term jolts). It is likely that 70 Watts of thumps is under 20 Watts of average heat (water-boil). That's before we discount the impedance bumps which are typically in the subwoofer passband.
Crest factor for speech/music under brutal distortion may be 6dB; for clean reproduction always over 16dB.
5/7/13-channel amps are not rated like lab-shaker amps; it is unlikely that ALL channels will pump FULL power at the same time. And not normally distorted. Taking 166W+333W+333W= 800 Watts and conservative 12dB crest factor means 75W input can support 1000W of DC and 800W of audio.
A sub-woofie may be driven to distortion, but not continuously (thump-a-thump, not boooooooom). A woofer voice-coil will not melt in one thump (and modern drivers will survive huge short-term jolts). It is likely that 70 Watts of thumps is under 20 Watts of average heat (water-boil). That's before we discount the impedance bumps which are typically in the subwoofer passband.
Funny, I assumed the OP was actually beefing about false advertising. Truth in advertising is a fine principle if the designers, manufacturers, distributors and consumers all lived in the one, sovereign country, all neatly regulated by one set of enforceable laws. ie. in a hermetic, non-global economy. No lies, but little incentive to strive for a competitive advantage.
So what do you prefer; honesty and plain truth advertising with the penalty of uniformly high costs and prices or maybe cheap prices for ordinary quality goods and let's just wise up and take the fanciful claims with the grain of salt they deserve?
So what do you prefer; honesty and plain truth advertising with the penalty of uniformly high costs and prices or maybe cheap prices for ordinary quality goods and let's just wise up and take the fanciful claims with the grain of salt they deserve?
Gotta risk stepping on quicksand here ..
I thought crest factor was a waveform attribute, rather than dynamic. A trumpet waveform can have a peak value (instantaneous, once per cycle) several times its RMS value -- but still be a continuously sounded tone, for example. PRR, I'm pretty sure you're one of the wisest blokes in these-here parts -- are you sure I'm wrong about this?😱
Cheers
I thought crest factor was a waveform attribute, rather than dynamic. A trumpet waveform can have a peak value (instantaneous, once per cycle) several times its RMS value -- but still be a continuously sounded tone, for example. PRR, I'm pretty sure you're one of the wisest blokes in these-here parts -- are you sure I'm wrong about this?😱
Cheers
Actually, it is both. Music has dynamics, which further increases the crest factor. But consider a simple tone plus its harmonic with equal amplitudes. Depending on the relative phase, the peaks may line up and require an envelope power four times as high as either tone alone, with an average power of only 2X. For two non harmonically related tones, you will always have a peak power Four times as high, because the constructive interference will occur periodically at the difference frequency. Do this with multiple tones and multiple harmonicas, and have the levels of each constantly varying, and it’s easy to have a crest factor or 20 dB. The only reason you don’t, all the time, is that compression is usually used in the recording process, and that some distortion for a few milliseconds at a time is not horribly objectionable.
The 1990, Dudley Moore, Daryl Hannah, Paul Reiser one? I thought that was how all advertising was developed.😉
Sure would explain some of the pseudo-logic we see presented ..
Just to be a little more *accurate* -- IMDB shows 3 others by the same name -- 1934, 2000 or 2018 .. dunno nuthin' about those.
Regards
edit: IIRC, Wikipedia had some assertions I took issue with, too.
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That's the one.
Basically if you start form the premise that all advertising is a load of lies and exaggeration then you won't go far wrong!
Trouble is most people don't believe in the power of marketing, yet they all go to McDonalds and buy the music players with the highest power "spec" and the fancy pseudo-science.
Be interesting to find the "legal" definition of music power by the advertising standards bodies.
Basically if you start form the premise that all advertising is a load of lies and exaggeration then you won't go far wrong!
Trouble is most people don't believe in the power of marketing, yet they all go to McDonalds and buy the music players with the highest power "spec" and the fancy pseudo-science.
Be interesting to find the "legal" definition of music power by the advertising standards bodies.
It got junked, another casualty in the globalization war.
Old FTC definition was strict and to the point, but with then tsunami of cheap bottom of the barrel Wal Mart and similar electronics, importers and distributors complained that rating was "unfair", since cut to the bone tiny heatsink tiny transformer products could NOT supply full RMS power "after 1 hour of preconditioning" , running LOUD with a constant sinewave so it was first downgraded to 1 hour or 30 minutes total, or something similar, no matter if it was in 5 minute bursts with 15 minutes rest because of thermal tripping.
And then was downgraded to basically "music power" because they measured just an instant, once.
Even PRO equipment now uses that twisted rating, you read ICE Power modules, or powerful Lab Gruppen, etc, to have some tiny print stating that "rated power can be sustained for up to 120 seconds, starting from cold"
I copypasted the pertinent line from a datasheet.
Old style "continuous power" can only be sustained at about 30% or 40% of rated power, the one which gets the headlines. 🙄
170W IcePower can supply 80 or 100W continuous "RMS", 8kW rated Lab Gruppen can only sustain 2kW and so on.
Admittedly, home Audio hardly uses above 15% of available power .... but PRO (or Musical Instrument) ones do not, are always near or beyond clipping respectively.
Old FTC definition was strict and to the point, but with then tsunami of cheap bottom of the barrel Wal Mart and similar electronics, importers and distributors complained that rating was "unfair", since cut to the bone tiny heatsink tiny transformer products could NOT supply full RMS power "after 1 hour of preconditioning" , running LOUD with a constant sinewave so it was first downgraded to 1 hour or 30 minutes total, or something similar, no matter if it was in 5 minute bursts with 15 minutes rest because of thermal tripping.
And then was downgraded to basically "music power" because they measured just an instant, once.
Even PRO equipment now uses that twisted rating, you read ICE Power modules, or powerful Lab Gruppen, etc, to have some tiny print stating that "rated power can be sustained for up to 120 seconds, starting from cold"
I copypasted the pertinent line from a datasheet.
Old style "continuous power" can only be sustained at about 30% or 40% of rated power, the one which gets the headlines. 🙄
170W IcePower can supply 80 or 100W continuous "RMS", 8kW rated Lab Gruppen can only sustain 2kW and so on.
Admittedly, home Audio hardly uses above 15% of available power .... but PRO (or Musical Instrument) ones do not, are always near or beyond clipping respectively.