Could somebody explain in simple English what the difference is in all the terms regarding power output. RMS, Music Power, Continuous Output, Class leading power etc, etc. For example, I have always understood that an amplifier advertised at a rating of 100 watts per channel music power in effect means 50 watts per channel RMS, so a bit of a con. Is that correct? I for example have speakers (just aquired, B&W XT4) which require a rather powerful amp. I have a Denon 80 watts per channel RMS. The Cambridge Audio Topaz SR20 for example has `a class leading power of 100 watts per channel´ , sounds like a good deal, does that means 100 watts RMS? Also if simply advertised as 100 watts per channel how does one know?? Many thanks.
RMS, Music Power, Continous Output etc....
- Thread starter gisgillen
- Start date
eggontoast
Well-known member
gisgillen said:
Without getting to deep, RMS & continuous power are a proper indication of an amplifiers output; if it manages to double the watts when the load is halved even better. Music power usually means peak output so is marketing BS, its difficult to get an rms figure from it as you don't know what they have measured (it generally means peak to peak power). If they have used a music power reference it will generally mean it is not very powerful though. Class leading power is a new one on me, but the specs for the Cambridge amp are 100Wrms on the Richer sounds website. You can also get instantaneous power which is power output for a very short period, NAD used to use this term for their power envelope technology which gives high power for short bursts, enough for music transients.
eggontoast
Well-known member
double post, does anyone else have problems posting on this site........I struggle to log on these days *sad*
Best to look at its operating power (consumption) - not all watts are equal.
Eg a 60wpc amp with an opc of 250watts will not sound as big as a 60wpc @ 500watts opc.
The higher you go you'll notice the operating power grows even though you're still looking at a 60 to 100wpc amp.
When you check specs that's what you look at.
Eg a 60wpc amp with an opc of 250watts will not sound as big as a 60wpc @ 500watts opc.
The higher you go you'll notice the operating power grows even though you're still looking at a 60 to 100wpc amp.
When you check specs that's what you look at.
Al ears
Well-known member
Thompsonuxb said:
I very much doubt you are going to find this from any manufacturer that quotes their amps output in music power.
shadders
Well-known member
Hi,
If we assume peak power is music power then the following applies.
RMS Power is Peak Power divided by the Square_Root of 2 (two). This is approximately multiplying Peak Power by 0.707 to obtain the RMS Power.
The CA SR20 specification states it is 100watts RMS. You need to download the specification from the support part of the website.
Regards,
Shadders.
If we assume peak power is music power then the following applies.
RMS Power is Peak Power divided by the Square_Root of 2 (two). This is approximately multiplying Peak Power by 0.707 to obtain the RMS Power.
The CA SR20 specification states it is 100watts RMS. You need to download the specification from the support part of the website.
Regards,
Shadders.
Al ears said:
It's in the specification listings on most amps - WHF list them in their online reviews under specification.
Just back from central america, Nicaragua and Costa Rica, counting monkeys mainly.
The subject of power ratings is an odd one, there really is so little consistency in written sprcifications that they are virtually useless.
RMS ratings tend to be considered the benchmark, but sadly they are of little use, they can be so easily manipulated. in fact very little of what the manufacturer gives you is any use at all.
The most useful rating is probably 'peak power', ie the output that an amplifier can sustain without clipping. Sounds simple but specifying the load conditions and the time period that the peak power can be sustained is difficult. Ideally you want an amplifier that can sustain it's peak power for the duration of that peak, then do it again a few fractions of a second later, very difficult to specify and even harder to measure.
Amplifiers that can do this will usually have bigger power supplies, sound more dynamic and drive more complex speakers. They are simply more capable than lesser amplifiers and in most systems you can hear it.
To give an example. Take the average, accurately specified, 50 watt RMS amplifier, as mentioned above this gives a peak power of √2 x 50, a little over 70 watts. Maximum peak power of 70 watts is the limit but this is into 8 ohms, but if the speaker dips to 4 ohms, as so many do, maximum power is now 140 watts!
Lets assume we have a nice modern recording with a good dynamic range of 40dB, the average power is therefore 20dB below peak power or 0.7 watts at 8 ohm or 1.4 watts into 4 ohms. So in the real world your amplifier, producing around 1 watt in these circumstances is on the edge of clipping.
Note that some more heavily compressed 'modern' recordings will require higher continuous power for the same 70 watts peak power, in some cases, though still well below the rated 50 watts this higher continuous power is too much for many budget amplifiers.
The subject of power ratings is an odd one, there really is so little consistency in written sprcifications that they are virtually useless.
RMS ratings tend to be considered the benchmark, but sadly they are of little use, they can be so easily manipulated. in fact very little of what the manufacturer gives you is any use at all.
The most useful rating is probably 'peak power', ie the output that an amplifier can sustain without clipping. Sounds simple but specifying the load conditions and the time period that the peak power can be sustained is difficult. Ideally you want an amplifier that can sustain it's peak power for the duration of that peak, then do it again a few fractions of a second later, very difficult to specify and even harder to measure.
Amplifiers that can do this will usually have bigger power supplies, sound more dynamic and drive more complex speakers. They are simply more capable than lesser amplifiers and in most systems you can hear it.
To give an example. Take the average, accurately specified, 50 watt RMS amplifier, as mentioned above this gives a peak power of √2 x 50, a little over 70 watts. Maximum peak power of 70 watts is the limit but this is into 8 ohms, but if the speaker dips to 4 ohms, as so many do, maximum power is now 140 watts!
Lets assume we have a nice modern recording with a good dynamic range of 40dB, the average power is therefore 20dB below peak power or 0.7 watts at 8 ohm or 1.4 watts into 4 ohms. So in the real world your amplifier, producing around 1 watt in these circumstances is on the edge of clipping.
Note that some more heavily compressed 'modern' recordings will require higher continuous power for the same 70 watts peak power, in some cases, though still well below the rated 50 watts this higher continuous power is too much for many budget amplifiers.
Vladimir said:
However I note you have been running rampant in a few threads while we were away, tut, tut!
I'd guess that class leading power is pure marketing fluff meaning that it's one of the most powerful amps at that price.
I'll go along with what Dave said.....
To achieve what he describes though requires a 'big enough' power supply. Hence why the operating power figure is important.
Having a high RMS rating in itself means little (as you can find with many budget amps) if the operating power is low (as you will find with many budget amps......er.....again).
Look round the back of your amp it'll usually say in watts.
To achieve what he describes though requires a 'big enough' power supply. Hence why the operating power figure is important.
Having a high RMS rating in itself means little (as you can find with many budget amps) if the operating power is low (as you will find with many budget amps......er.....again).
Look round the back of your amp it'll usually say in watts.
Jota180
Well-known member
Jota180 said:
Many of the females had young, that would be most inapropriate!
Part of a project looking at the numbers of the smaller indiginous species, particularly the squirrel and howler monkeys in relation to the more wide ranging spider monkeys.
The conclusion being that they are doing alright despite the pressures of a developing country, most notably Costa Rica.
chebby
Well-known member
chebby said:
Would this be an appropriate time to suggest that I might be seriously considering a new system?
(Actually Costa Rica is developing quite nicely and managing to stay well clear of the region's 'alternative' economy. Hopefully it stays that way.)
eggontoast
Well-known member
davedotco said:
Not sure what rms figures you have seen which are manipulated. If the specifications give an rms figure for 8ohms, 4ohms and 2ohms (which they usually do) this gives a good indication of power, especially if the power doubles as the impedance halves. Very rarely do you see manipulated figures from Hi-Fi manufacturers; in most cases the amplifiers exceed their specification when tested.
eggontoast said:
Which is itself a form of manipulation....! Everyone knows that 'Naim watts' are more powerfull than 'ordinary watts'.
Mostly the figures are manipulated by not being complete. Many mainstream amplifiers are now quoting power into 6 ohms, not 8 ohms as was once considered the norm. They may well deliver the rated power into an 8 (or6) ohm resistor, but a real world speaker like a B&W where the impedance drops to 3.2 ohms?
Similarly, how long can they maintain this power? Driving heavily compressed music into a difficult low impedance speaker is quite difficult, many mainstream amplifiers will not cope well under these conditions even though the actual continuous power delivered by the amplifier is way below it's specified continuous power ratings. The power ratings are of little use in these examples.
How can manufacturers get away with this? Simple, in my first post I showed how little continuous power is required by most systems most of the time, as long as the amplifier is only called upon to produce such power, remember 1 watt into an average speaker may produce 87dB spl, already very loud, they will be absolutely fine.
But in more demanding system? Low sensitivity speakers, low impedence speakers, heavily compressed music, a bit of bass boost, higher than average playback levels and pretty soon the amplifier that was doing so well in the previous paragraph is now hideously out of it's depth.
The important thing for anyone coming to this hobby for the first time is to understand how few watts are needed most of the time and how many are required the moment we ask a system to 'do a little more'.
Blacksabbath25
Well-known member
Blacksabbath25 said:
The Upgraded Abrahamsen is all about the power supply, it's no secret, just rather expensive.
Yet the Abrahamsen is 'only' 70 watts, amplifiers with the same rating (measured, not claimed) can be had for around one third of the price.
As a user, perhaps you would care to explain why your amplifier is so much better than those of similar power at a much cheaper price?
Vladimir said:
I think the question is more a question of 'whether' you live rather than 'where'....*unknw*
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