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Output power of amplifiers
Output power of amplifiers
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Old 29th November 2020, 12:35 AM   #11
MarsBravo is offline MarsBravo  Netherlands
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One cannot squeeze more power out of a machine then what is put in. #2 is perfectly clear, and the rest is marketing (fairy tales). I agree with #6, #8 and #9 - psychology can supply many answers here...
Keep in mind that in the recent past perception or experience were rooted in 'tubes', handwriting and personal introductions: proof was needed whatsoever. In our current times however, expectation, promise and 'mediasation' has changed this perception. One rule keeps afloat: PROOF. No obedience, no belief.
Oh, I can tell you a fantastic story...
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Old 29th November 2020, 06:41 AM   #12
ferret is offline ferret  South Africa
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Quote:
Originally Posted by duncan2 View Post
Movie theater Noise .....
"certain types of high spectacle movies , such as Transformers ,have decibel levels of 90db for almost the entire movie and have decibel levels of 120db for significant periods and some points getting to 130db .
Now 130db is a jet engine at about 10--TEN meters "

And that is why I insist on using ear plugs in the cinemas. The sustained barrage on our ears is just insane. I walked out of a cinema last year (took my son to see one of the newer animated films) and in no uncertain tones told the manager that they had better turn the volume down - the majority of the viewers were children under the age of ten. Man was I pissed off. He did get the volume turned down to an acceptable level.
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Old 29th November 2020, 08:01 AM   #13
altec9440 is offline altec9440  France
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In broadcast studio industries, a P20 amplifier is given for 20W, but it's in fact a 40W RMS to keep dynamic.
More for less is a usual argument in business : PMPO and others big powers are only tricks.
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Old 29th November 2020, 08:21 AM   #14
forr is offline forr  France
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W are W .
W RMS is a misnommer for W.
Applying the RMS calculation to power is a nonsense.


Note that the power of an amplifier always emanates from the measure of voltage in V in a load in Ω.
The specifications of amplifiers using voltage in V across load in Ω would clear up the constant confusion about their power.

Last edited by forr; 29th November 2020 at 08:34 AM.
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Old 29th November 2020, 08:32 AM   #15
steveu is offline steveu  United States
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There are two issues:
1. Speaker efficiency. Professional speakers are roughly 10x the efficiency of consumer entertainment systems. It's about size, precision and engineering vs marketing. Professional bass and mid range speakers are at least 15 inches. Bose, for example is a marketing company and their classic product require huge amounts of electrical power to produce reasonable sound levels. Speakers have an efficiency rating based on the acoustic level in dBA at a distance of one meter.
2. Amplifier power exaggeration. Marketing has found a long list of excuses to exaggerate the power output of amplifiers, such that the specification is as much as 8x the actual continuous RMS power. You will see phases like "music power", "peak power" etc. This kind of marketing fraud was ramped when "solid state" amplifiers were new and transistors were expensive.
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Old 29th November 2020, 01:30 PM   #16
anti is offline anti  Slovakia
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Quote:
Originally Posted by altec9440 View Post
In broadcast studio industries, a P20 amplifier is given for 20W, but it's in fact a 40W RMS to keep dynamic.
More for less is a usual argument in business : PMPO and others big powers are only tricks.
Pre-compression audio has quite a bit higher crest factor so that surely has to be factored in. Perhaps not as high in broadcast rooms as it used to be in analog era recording studios, but still.
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Old 29th November 2020, 01:48 PM   #17
RayLi is offline RayLi
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It sounds big power has not much effect to the customers. It has lost the direct comparison between models and not in breach with any legislation. If the suppliers prefer to quote PMPO, it does not matter but the measurement method must be standardized for direct comparison of the results. Currently every supplier applies to their own method. It is no way to do a fair comparison before decide to purchase.
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Old 29th November 2020, 01:50 PM   #18
wg_ski is online now wg_ski  United States
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Quote:
Originally Posted by steveu View Post
2. Amplifier power exaggeration. Marketing has found a long list of excuses to exaggerate the power output of amplifiers, such that the specification is as much as 8x the actual continuous RMS power. You will see phases like "music power", "peak power" etc. This kind of marketing fraud was ramped when "solid state" amplifiers were new and transistors were expensive.
Current draw ratings these days are only for what the amp “typically” draws from the wall, not the maximum that it could draw. If it were the latter, you wouldn’t legally be allowed to plug it into anything short of an electric range outlet. The amp in this example is “rated” to draw 13.9 amps on the back panel. I’ve had it getting the speakers starting to smell, and never had the breakers trip. Sine wave testing into a water heater element will trip it in about 10 seconds.

How long an amp can put out full power is all over themap, and generally you get what you pay for, and no more. The amp in question will put it out long enough for most practical purpose. You can buy better, for $3-5000. You can do much worse.
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Old 30th November 2020, 12:37 AM   #19
RayLi is offline RayLi
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We are in discussion of music output power of amplifier to the speakers, not the rated power drawn from power outlet.
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Old 30th November 2020, 05:10 AM   #20
wiseoldtech is offline wiseoldtech  United States
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Forr's post #14 is actually an accurate description of audio amplifier "wattage" rating.
People have been led to believe in the "RMS" value for decades, and with audio frequencies, there isn't any accurate form of dealing with anything RMS.


Perhaps a more sensible and accurate way to rate any given amplifier is its ability to supply a particular decibel level (cleanly) as a result for a particular speaker.


Wattage isn't everything, I find it interesting that many people seem to go after amplifiers/receivers in the 20-40 "watt" range.
For instance....

Why is something like a 1970 Harman Kardon 330A/B draws so much attention in audio circles?
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