Things you always wanted to know the answer to [Vol. 5]
Discussion
Doofus said:
When it come to audio, does Watts relate purely to volume?
If so, how come a 50w speaker in my kitchen is more than loud enough but my car apparently needs a 1,000w stereo?
If watts aren't just about volume then what are they about?
Whilst a watt is a watt there are two different ways of measuring a Hi-Fis output - RMS is the standard output, PMPO is what a speaker system can do at peaks. You'll probably find the kitchen speaker is measuring RMS, the car stereo peak. If so, how come a 50w speaker in my kitchen is more than loud enough but my car apparently needs a 1,000w stereo?
If watts aren't just about volume then what are they about?
https://askanydifference.com/difference-between-rm...
Funnily enough the less honest manufacturers tend to advertise PMPO numbers, "proper" manufacturers will use RMS.
bodhi said:
Doofus said:
When it come to audio, does Watts relate purely to volume?
If so, how come a 50w speaker in my kitchen is more than loud enough but my car apparently needs a 1,000w stereo?
If watts aren't just about volume then what are they about?
Whilst a watt is a watt there are two different ways of measuring a Hi-Fis output - RMS is the standard output, PMPO is what a speaker system can do at peaks. You'll probably find the kitchen speaker is measuring RMS, the car stereo peak. If so, how come a 50w speaker in my kitchen is more than loud enough but my car apparently needs a 1,000w stereo?
If watts aren't just about volume then what are they about?
https://askanydifference.com/difference-between-rm...
Funnily enough the less honest manufacturers tend to advertise PMPO numbers, "proper" manufacturers will use RMS.
Slightly surprising that noone has mentioned the relationship between PMPO and RMS, PH being the haven for geekery that it is.
RMS means Root Mean Square and is the average of the roots of the squares of all the values between a waveform of a given amplitude and its baseline.
Used to be called the Quadratic Mean too, but I haven't heard the term used for decades.
Put simply RMS is 0.707 of peak value. Thus a device outputting 1kW (PMPO or Peak Music Power Output) will have a RMS value of 707W. Conversely, 1kW RMS can be expected from a device capable of 1415W (give or take a smidge) PMPO.
It's generally taken that RMS is the maximum continuous output without distortion, but that's more a rule of thumb than a law as other variables come into play. Notably frequency and the ability of the hardware to deal with very high or very low frequencies.
At least that's my memory of it, but I'm a structural/mechanical engineer. I'm sure there is a proper geek in the room somewhere!
RMS means Root Mean Square and is the average of the roots of the squares of all the values between a waveform of a given amplitude and its baseline.
Used to be called the Quadratic Mean too, but I haven't heard the term used for decades.
Put simply RMS is 0.707 of peak value. Thus a device outputting 1kW (PMPO or Peak Music Power Output) will have a RMS value of 707W. Conversely, 1kW RMS can be expected from a device capable of 1415W (give or take a smidge) PMPO.
It's generally taken that RMS is the maximum continuous output without distortion, but that's more a rule of thumb than a law as other variables come into play. Notably frequency and the ability of the hardware to deal with very high or very low frequencies.
At least that's my memory of it, but I'm a structural/mechanical engineer. I'm sure there is a proper geek in the room somewhere!
Rich Boy Spanner said:
It was a thing back in the days when people bought Hi-Fi stack systems and even the midi and micro systems. The reputable manufacturers always quoted RMS and the low end stuff always quoted peak. One of those things that seem lost in time now.
Often, but not always the case. As a teenager growing up in the 90's I would have cut my right testi off with a rusty blade to have a certain model of Philips Turbo Bass CD ghetto blaster. It had 80 watts PMPO. As well as Philips, Sanyo was another (then) mainstream brand who always used PMPO. @ error 404. I always thought RMS stood for Real Music Sound?Fermit said:
Often, but not always the case. As a teenager growing up in the 90's I would have cut my right testi off with a rusty blade to have a certain model of Philips Turbo Bass CD ghetto blaster. It had 80 watts PMPO. As well as Philips, Sanyo was another (then) mainstream brand who always used PMPO. @ error 404. I always thought RMS stood for Real Music Sound?
Nope Fermit; definitely Root Mean Square. Although I suppose Real Music Sound is in effect a fair-enough interpretation.
I'm sort of familiar with it because it's a consideration for anything that oscillates including RF propagation (radios/radars &c) and even structures that are subject to vibration and can start to oscillate, like bridges in windy environments for example. And other stuff.
Straying somewhat from the original question though.....
Nope Fermit; definitely Root Mean Square. Although I suppose Real Music Sound is in effect a fair-enough interpretation.
I'm sort of familiar with it because it's a consideration for anything that oscillates including RF propagation (radios/radars &c) and even structures that are subject to vibration and can start to oscillate, like bridges in windy environments for example. And other stuff.
Straying somewhat from the original question though.....
Fermit said:
Rich Boy Spanner said:
It was a thing back in the days when people bought Hi-Fi stack systems and even the midi and micro systems. The reputable manufacturers always quoted RMS and the low end stuff always quoted peak. One of those things that seem lost in time now.
Often, but not always the case. As a teenager growing up in the 90's I would have cut my right testi off with a rusty blade to have a certain model of Philips Turbo Bass CD ghetto blaster. It had 80 watts PMPO. As well as Philips, Sanyo was another (then) mainstream brand who always used PMPO. @ error 404. I always thought RMS stood for Real Music Sound?
ks.I remember seeing a small Sony system rated at something like 300W PMPO with a mains power consumption of something like 18W. Seems Sony invented a machine that outputs more power/energy than it consumes!
98elise said:
Error 404 is correct. RMS is the proper scientific term. PMPO is just made up marketing bks.
I remember seeing a small Sony system rated at something like 300W PMPO with a mains power consumption of something like 18W. Seems Sony invented a machine that outputs more power/energy than it consumes!
Watts of electrical consumption is not the same as Watts of music output.ks.I remember seeing a small Sony system rated at something like 300W PMPO with a mains power consumption of something like 18W. Seems Sony invented a machine that outputs more power/energy than it consumes!
David87 said:
Currently in the US. Am always irritated by the ESTA and more recently, COVID vaccine bks. Do we put Americans through a similarly irritating process when they travel to the UK? I hope so. 
Not in my experience.ks. Do we put Americans through a similarly irritating process when they travel to the UK? I hope so. If you can, the 'upgrade' to Global Entry (which is not a euphemism) is seemingly worth going for.
David87 said:
Currently in the US. Am always irritated by the ESTA and more recently, COVID vaccine bks. Do we put Americans through a similarly irritating process when they travel to the UK? I hope so.
Shortly after WW2, the UK started to allow Mericans visa-free access to the UK. IIRC, it took them 47 years to reciprocate. T'was ever thus.ks. Do we put Americans through a similarly irritating process when they travel to the UK? I hope so. RMS = Root mean square
or the root of the mean of the sum of the squares
essentially, its an equivalent measurement to DC so a 5V RMS signal has the same power to a load as a 5V DC signal
PMPO, peak music power output just allowed advertisers to use a bigger and meaningless number
or the root of the mean of the sum of the squares
essentially, its an equivalent measurement to DC so a 5V RMS signal has the same power to a load as a 5V DC signal
PMPO, peak music power output just allowed advertisers to use a bigger and meaningless number
Edited by Gary C on Tuesday 4th April 14:12
Gary C said:
RMS = Root mean square
or the root of the mean of the sum of the squares
essentially, its an equivalent measurement to DC so a 5V RMS signal has the same power to a load as a 5V DC signal
PMPO, peak music power output just allowed advertisers to use a bigger and meaningless number
Wasn't PMPO about 4 x RMS or was there a similar rule of thumb? Was there also PMO figure as well, which was about 2 x? or the root of the mean of the sum of the squares
essentially, its an equivalent measurement to DC so a 5V RMS signal has the same power to a load as a 5V DC signal
PMPO, peak music power output just allowed advertisers to use a bigger and meaningless number
Edited by Gary C on Tuesday 4th April 14:12
It's all a very long time ago, 30 years +, and I recall pouring over catalogues comparing output figures but the details are hazy
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