I've recently gotten back into the audio world and it seems that everyone
is using some silly name to rate their wattage other than using RMS.
I'd rather they just say it's 10 watts per channel RMS than 127 music power
or dynamic power or whatever silly name marketing has come up with.
is using some silly name to rate their wattage other than using RMS.
I'd rather they just say it's 10 watts per channel RMS than 127 music power
or dynamic power or whatever silly name marketing has come up with.
Nothing new about this, that's why in the early 1970s the FTC came up with rules about rating amplifier output power after preconditioning at a specified power for a specified period of time. Legitimate HIFI gear still carries these ratings and often a short term dynamic headroom rating as well.
Car stereo, cheap PA and mid-fi gear made offshore often carry ridiculously inflated power claims.
Here is the last I know about the rules and changes to them made in the early 2000s. (Marked the end of my involvement in the design of commercial HIFI gear)
https://www.ftc.gov/sites/default/f...roducts/001222traderegulationrulerelating.pdf
Car stereo, cheap PA and mid-fi gear made offshore often carry ridiculously inflated power claims.
Here is the last I know about the rules and changes to them made in the early 2000s. (Marked the end of my involvement in the design of commercial HIFI gear)
https://www.ftc.gov/sites/default/f...roducts/001222traderegulationrulerelating.pdf
A more important measure is power supply voltage.
Even with a couple of watts the transient peaks can be massive if the track isn't compressed.
I got caught out with this on a first amplifier build.
It clipped well before it got loud.
So I found an amp with twice the volts and that sounded much better.
Even with a couple of watts the transient peaks can be massive if the track isn't compressed.
I got caught out with this on a first amplifier build.
It clipped well before it got loud.
So I found an amp with twice the volts and that sounded much better.
Interesting read thank you
and Yes I tend to view manufactures who do Not use RMS as less than legitimate.
Probably the most ridiculous abbreviation ever invented on the audio marketing department regarding wattage must be PMPO (Peak Music Power Output), without being an expert on PMPO I can type the following with eyes shut... it's a fraud. 
As far as I can remember the PMPO markeing bs has been around already for a few decades and used to be once upon a time associated with car audio gears, never saw that used anywhere else back then.
One quite recent and suitable PMPO fraud candidate speaker excessively hyped up by the company itself boasting a whooping 4500 Watt from a relatively tiny package of roughly two bowling balls must be the Phantom speaker, let alone the premium price ~$3000.
Phantom: high-end wireless speaker - Devialet
Audio power - Wikipedia
PMPO Power Rating - Turning 16 W into 700 W! - YouTube
As far as I can remember the PMPO markeing bs has been around already for a few decades and used to be once upon a time associated with car audio gears, never saw that used anywhere else back then.
One quite recent and suitable PMPO fraud candidate speaker excessively hyped up by the company itself boasting a whooping 4500 Watt from a relatively tiny package of roughly two bowling balls must be the Phantom speaker, let alone the premium price ~$3000.
Phantom: high-end wireless speaker - Devialet
Audio power - Wikipedia
PMPO Power Rating - Turning 16 W into 700 W! - YouTube
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When the marketing department got involved!
I worked as a repair tech in an Olson Electronics store in 1971 and 1972. We sold a brand of plastic stereos called Symphonic. The most popular model claimed "72 watts IPMP" (similar to PMPO) from a pair of TO92 sized transistors. After measuring about 3 W RMS per channel I asked the Symphonic rep about the power spec.
IPMP is Instantaneous Peak Music Power, basically the short circuit current through the speaker multiplied by the open circuit voltage across the speaker when the amp is driven to clipping into its rated impedance. Most amps sold in 1972 would blow up when its speaker leads were shorted at full crank.
Similar insanity still happens today in the powered computer speaker market. Here it is possible to find "200 watt" speakers powered by a 12 volt wall wart that makes about 2 amps on a good day.
PMPO was basically a con so they could use smaller power caps and smaller mains transformer to lower costs.
Maplin used to do a disco amplifier in 1980 and that was 225WRMS into 4 ohms and the power supply was +/-55 volts with a huge transformer.
Maplin used to do a disco amplifier in 1980 and that was 225WRMS into 4 ohms and the power supply was +/-55 volts with a huge transformer.
I've measured tabletop "mid fi" stereos claiming "50+50 watts RMS" and they actually produced closer to 12 watts a channel, both channels driven continuously, into dummy loads. They would produce 50 watt transients without clipping. This is not as bad as it sounds and in practice is pretty powerful when reproducing music. Sine waves, it's 12 watts a channel
On the other hand, an old Pioneer receiver from the early 90s rated 60 watts a channel into 8 ohms did just that (a dumpster receiver at that!) continuously, into dummy loads. It produced 120 watt peaks without clipping. It is designed to drive two pairs of 8 ohm speakers in series when the speaker selector is set to "A+B."
One unit rated 50+50 watts RMS, the other rated 60+60 watts RMS. In measurements and listening tests, the Pioneer blows the Philips Magnavox (circa 2000) right out of the room.
Most power ratings today are pure BS. They're not even handy for comparison unless you're looking at nicer stuff. Generic stuff at Walmart is guaranteed to be BS. You have to measure.
On the other hand, an old Pioneer receiver from the early 90s rated 60 watts a channel into 8 ohms did just that (a dumpster receiver at that!) continuously, into dummy loads. It produced 120 watt peaks without clipping. It is designed to drive two pairs of 8 ohm speakers in series when the speaker selector is set to "A+B."
One unit rated 50+50 watts RMS, the other rated 60+60 watts RMS. In measurements and listening tests, the Pioneer blows the Philips Magnavox (circa 2000) right out of the room.
Most power ratings today are pure BS. They're not even handy for comparison unless you're looking at nicer stuff. Generic stuff at Walmart is guaranteed to be BS. You have to measure.
When Class-B amplifiers were invented (around AD193x). It makes statistically and psychoacoustically sense, if the amp can deliver twice the RMS power (RMS power to me means power for
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Using RMS for wattage is silly.
20 Vrms in a 8 Ohm resistor give 50 W, not 50 Wrms.
RMS is a mathematical operation which applies to Voltage or to Current, not to Wattage.
It is a typical example where marketing services have imposed their "science" and the concerned engineers did not protest.
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Yes, so in German long-term output power is called Sinusleistung, because a sine has infinite duration.
Watts in their various forms are here to stay, then there is the mysterious Chinese Watt...........
When an engineer sees their friends laid off for protesting, or even explaining basic physics to marketing, management or even stupid "dreamers" from the "future concept" group, one learns to say nothing! It will be ignored any way. I have plenty of examples from my 41 year engineering career.
True, but said mathematical expression can and probably should be used to quantify RMS volts * RMS amps into a resistive load (PF = 1.0). Any other use of the term "watts" is likely created by marketing to sell amplifiers.
"Wattage" has been around about as long as "Amperage." The Watt is a unit of measure used to express power. There are others, like "Horsepower" commonly used to express the mechanical power produced by a motor or engine. Even in the USA Volkswagen often quoted their engine power in Kilowatts, at least through the 1980's. 1 Horsepower = 746 Watts.
a circuit breaker is 15 Amps, which is 120Vx.8x15 Amps= 1440 continuous Usable watts, breakers will trip if more than 1500Watts is sustained.
a class AB amplifier is around 85% efficient at highest power = 1224 watts
Each channel max power is then half : 612 Watts.
This is quite a high dynamic power.
a class AB amplifier is around 85% efficient at highest power = 1224 watts
Each channel max power is then half : 612 Watts.
This is quite a high dynamic power.
RMS should never be applied to power, but some standards body (DIN?) invented this peculiar measure some time ago (1960s?).
(RMS voltage)^2 divided by resistance equals average power - it does not equal RMS power, because to a real engineer or physicist there is no such thing as RMS power.
Personally I hate the terms 'wattage' (power) and 'amperage' (current) but I know what people mean when they use them. It is often, but not always, a clue that the person is new to understanding electronics - although not perhaps new to making/mending/using electronics. Perhaps I should be grateful that people do not speak of faradage (capacitance) or henriance (inductance).
(RMS voltage)^2 divided by resistance equals average power - it does not equal RMS power, because to a real engineer or physicist there is no such thing as RMS power.
Personally I hate the terms 'wattage' (power) and 'amperage' (current) but I know what people mean when they use them. It is often, but not always, a clue that the person is new to understanding electronics - although not perhaps new to making/mending/using electronics. Perhaps I should be grateful that people do not speak of faradage (capacitance) or henriance (inductance).
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