What's with watts... I don't get it?

[The Vinyl Adventure]

Sorry to be my usual simple self but "wpc" has never sat well with me!
we get people in the shop all the time - usually kids, moaning that a very capable nad system only has 40wpc, and then lookin at the crappy Sony dav kits with thier 5 plastic crappy little speakers and puffy passive subs and exclaiming "wow that's more like it - 850 watts I bet that's well loud".

Basically I have no idea what to say to these people (apart from "sling ya hook oik".... I don't really ;) )

I understand that some of this is down to the sensitivity of the speakers... But that can't be all of it ... reading Martins thread about Marcos visit they are talking about the 30wpc copper amp being similar in output to the 350wpc chord.
And my 40wpc valve amp has much more oomph than my naim nac180 did and they are 90wpc I think! And I haven't changed my speakers...

Watts that all about then?? :eek:
Layman's terms where possible please

[Dave Cawley]

Only RMS watts count. All others are imaginary!

Dave

[The Vinyl Adventure]

Ha yeah, I remember that from when I bought my first hifi when I thought it matters how loud it was.
Il have a look, but I'm pretty certain Sony quote in rms, thier big "chav system" as I call it almost definatly claims about 240 watts rms... And it definatly doesn't have the balls of my system

[Kris]

Jeff has a Buick Roadmaster Estate Wagon. V8, 13mpg. I have a 1.8 Rover 600. 33Mpg. In theory the American V8 should eat mine for breakfast. But I bet in reality it's the other way around.

It's not the number of watts that count, it's the quality of the watts. A 89db speaker measures 89db at one meter from ONE watt. A 30 watt amp and a 350 watt amp, given proper designs, well, the number of watts is mostly immaterial.

Unfortunately, kids like playing the 'mines bigger than yours' game and to them the more watts the better. Like a Buick V8 is obviously faster and more powerful than my 1.8 Rover.

The 850 watt Sony is probably 850 watts PMPO (Peak Music Power Output) which is how much they can get out of it (at a horrendous distortion level) momentarily the fraction of a second before it blows up. PMPO bears no relevance to real life, it just looks good for the idiots who know nothing better. Very sad.

[Dave Cawley]

Sony quote in rms, thier big "chav system"

They don't.

Dave

[HighFidelityGuy]

There's lots of different things to take into account when it comes to comparing amps.
Most of these are going to be difficult to explain to chavs but it generally boils down to the quality of the components/design and the marketing spiel.

When companies like Sony make a budget piece of Hi-Fi equipment, they generally use the cheapest components that will do the job and then use marketing spiel and fancy flashing lights to lure in the chavs. Quality Hi-Fi gear is designed to sound good first and look good second and will contain the best components available within the limits of it's price point. Also, great care and attention will have been lavished on the design of the circuits by experienced designers. So signal paths will be shorter and not routed near parts of the circuit that may cause interference. etc.

It's easy to make a high powered amp out of cheap components but it's much more difficult and expensive to make a high quality amp. The transformers in high quality low powered amps are often bigger than those in higher powered cheaper designs. The transformer and overall power supply design is arguably the most important part of an amp design. So scrimping here is a big mistake and will reduce dynamics and overall sound quality.

Also on the subject of marketing spiel; lower end manufacturers will often over-rate their equipment to make it sound good to chavs on paper. So a £100 Sony amp may be rated at 200W per channel on paper but they will have used flawed tests to produce this figure. High quality manufacturers will use much more stringent test methods to produce their ratings and will then often publish a rating that's lower than what they measure to make sure that the published ratings are well within the limits of the product.

For example, a quality manufacturer may quote power and distortion figures that are accurate over the whole frequency range. A crappy manufacturer will find the best readings at specific single frequencies and then quote those. So a crappy amp may have good power output and low distortion at 1KHz but what about at 20Hz, or 20KHz. I bet the readings at those frequencies are terrible.

That's the gist of it. Hopefully you can take some useful selling points from that. :)

I used to work part time at Currys a few years ago, so I know what you're dealing with. I was taught to sell from the features. So you make a list of features about a quality amp like it's got high quality parts, over spec'd transformer, fantastic build quality etc and use that to sell the product for you. At the end of the day though you are fighting a bit of a loosing battle. There will always be those people that are too stupid to see past the flashing lights and marketing nonsense like Super XFR Mega Bass and bollocks like that. Don't spend too long trying to convert them, just sell them what they like the look of and pocket the commission. :lol:

I hope that helps. :)

[Puffin]

850 watts.....really? If it is supposed to put out that much someone is massaging the truth.

Most "stereos" would only put out a handful of watts before distortion sets in. The problem for manufacturers is building to a price point and the problem with heat build up.

I have a dB meter. My speaks are 97dB sensitive. I tried 1 Watt at 1 metre with a 2volt CD input. I had to stop before the meter got to 97dB as I was being pumelled to death.

Most people (including me) before I got a meter will grossly exaggerate how many watts are being used to make a noise.

[No Regrets]

Partial quote from Hamish....."I understand that some of this is down to the sensitivity of the speakers... But that can't be all of it ... reading Martins thread about Marcos visit they are talking about the 30wpc copper amp being similar in output to the 350wpc chord.
And my 40wpc valve amp has much more oomph than my naim nac180 did and they are 90wpc I think! And I haven't changed my speakers..."


There is a lot more to it. Very often, a smallish tube amp can sound as powerful or even more powerful than a solid state amp that has many more watts. It seem this way because of many things, a few of which may be that the input sensitivity of the tube amp may be greater than that of the solid state amp. Meaning that the tube amp may only require 500-750mV in to produce full output where as the solid state amp may require a full 2 or 2.5Volts in to get the full power output. That makes a big difference in percieved dynamics.

Also, is the matter of transconductance of the tubes which is directly related to dynamics. Additionally, tubes have the ability to clip more gracefully and recover much faster than the solid state devices which translates to sounding more smooth and less harsh or brittle when reaching their respective limits.

Depending on the speakers being used, there may be times when there is no substitution for sheer, powerful watts. Things to consider is the speakers sensitivity, the speakers impedance (how high or low, how flat or uneven or how reactive it is).

So there is a lot that needs to be considered, even more than what I have gone into, but hopefully this provides a little food for thought.

Take care,
Don (No Regrets)

[The Vinyl Adventure]

Il have a closer look at sony's claims tomorrow when i'm in the shop

fortunately most customer who do genuinly ask about watts have been happy with my, now 4 years standard response of "it's in my experience that the quoted output has no relationship to how loud one system is compared to another, how loud it goes isn't really important either, it's the quality of the sound that matters and that is for you to decide by having a listen, I have a wide veriety of music on cd and my iPhone (we sell mostly dock systems these days), what sort of money were you looking at spending - I will happily demo any ofthe systems we have in store" or somthing along those lines.
I doubt I would ever go into the details with any customer, I just prefer to know the info if someone pushes me for it.
We aren't a shop that pushes the specs and figures, fortunately we are an independant so I can sell stuff how I like... And I chose the 'honest demonstation of best quality for customers budget' route (unless I'm selling cameras, in which case make sure you got a few hours on the car parking ticket and be prepared to hear about everything from oskar barnark to pixel size ;) )

[The Vinyl Adventure]

Cheers for all the info though, most informative! I shall read it about 6 or 7 more times and hopefully come to a greater level of knowledge ;)

[The Grand Wazoo]

Hamish,
I own a 15 watt (as per spec) amp that actually is capable of about 22 watts (it's an old, old Radford valve amp) and a bi-amped system with Mark Levinson power amps - total potential of 50 watts to mid & treble & 100 watts goosing up the bass end of things. I'm also running an 80 wpc receiver in the room I'm sitting in now & there's a 12 wpc set up in the bedroom.

Whatever I'm listening to I have to consider the neighbours when I approach the volume control!

Because these things are measured in a non-linear scale, the first 5 or 10 watts are all you'll ever need for most of what you hear. I could get anti-social with any of those set-ups!!!

[goraman]

Hammish let me enlighten abit,
RMS stands for Root mean square,This is at full power with out clipping into an 8 ohm load in most cases or unless other wise stated. RMS is not the extream peak of the discharge of the tube or transistor but the constaint steady voltage and amprage.
Volts X Amps= watts

Watt measured in PEP. The Peak Envelope Power is a burst of power at just a fraction of a second the extream discharge of energy from the tube or transitor.

Measurements have become very liberal with a new term (music power)
Techs have told me they messure PEP with the meter weighted to swing wider giveing a stupid over exagerated wattage reading.

A watt is a watt into the same load,for example 8ohms,but there are sevrel factors that can make better use of that watt.
For example speaker efficency as to get 3db. you must doubble the power so a 100db. speaker needs 4 watts to reach 106.
Do the math with an 86db. speaker. 128 watts! So the amp and speaker are both just as importaint.

The next comment is for Kris.

As for my wifes road master,the cam is pretty mild sauce,it is a 93 with the L05 350 CID motor at 180 horsepower and 300 FPT. made for towing heavy loads 8 pasengers,luggage and a 5,500 trailer.It dose have a 4 speed overdrive and had no problem keeping speed 80mph up the steep grapevine when everyone else diapeared in the rearveiw mirror.

in 94 the same car used the LT1 motor and with the electronic limitor removed will do 150 mph! Still a 350 motor but built to flow fuel. They produce 350 hosepower and 330 foot pounds of torqe! but 13 to 14 miles per gallon is rare around town in these cars. but both get 22miles per gallon on the freeway.Not bad for a 5.7 liter motor huh?
http://www.youtube.com/watch?v=HwIaX61vMrA&feature=related

http://www.youtube.com/watch?v=Aumq36HKWMA

My wifes motor
http://www.youtube.com/watch?v=PkCHfMytm1Y

This was the same car I had in high school,with the dual quad option(same as this car you could spin the tires as long as you had it floored.You had to let up to get her some traction. I always turned 13's in the qaurter mile.The plant was a 455 cubic inch motor (7.6Liter) with 2X 4 barrel quadrajet carbs . 400 horsepower in a near 5,000 pound car!Never more than 8 miles per gallon.http://www.youtube.com/watch?v=7D_Qo3tJVLY&feature=related


Id still race Kris.

[The Vinyl Adventure]

Cheers, Jeef ( ;) ) I do wish I had a better grasp of the technicals and to be fair, what you say is quite familiar and doesn't escape me completely, but for some reason it just doesn't stick... Tell me something about photography or camera's and it sticks like glue in my brain!
you do like your wifes car eh? I saw the pic on the other thread ... You gotta love that wood trim down the side! I do like American cars - bloody useless on our roads mind, I dont think you would even fit that car down my road, there at cars parked either side that leave hardly enough room for the piddly things people drive over here!

[goraman]

Cheers, Jeef ( ;) ) I do wish I had a better grasp of the technicals and to be fair, what you say is quite familiar and doesn't escape me completely, but for some reason it just doesn't stick... Tell me something about photography or camera's and it sticks like glue in my brain!
you do like your wifes car eh? I saw the pic on the other thread ... You gotta love that wood trim down the side! I do like American cars - bloody useless on our roads mind, I dont think you would even fit that car down my road, there at cars parked either side that leave hardly enough room for the piddly things people drive over here!

I put up 3 links for fun. My wifes car is nearly 3 tons or right at full of gas,the idea was to keep her and my new born son safe.Gross tonage and air bags,saftey belts and car seats where a big factor not gas milage in my choice for her first car.

Just think of RMS as steady light and peak envolope power as the flash,and music power as chickin little discribeing the flash!

[The Vinyl Adventure]

:lol: I like the analogy!

It sounds like you have bought the american equivelent of a Volvo estate, probably quite a small car over there?
The mums over here drive the big off road cars to get the advantage you have bought for your wife!

[Hypnotoad]

I thought the same thing are watts really watts.

I bought a JVC 7.1 receiver from Frys Electronics on sale for $110.00 and thought this marvel puts out 110 watts per channel.

I connected it to some Advent speakers, not the most efficient but not that hard to drive.

I would usually have the volume just over half way to get the desired level in two channel stereo mode.

Then I happened across my now main amp the venerable Luxman L-430 rated at 105 watts per channel.

I hooked it up to the Advents and if I even attempted to turn in up to half way I would be in danger of stripping the paint from the walls.

Hmmm somethings fishy here.

Now the Luxman weighs in at almost 30lbs the JVC half that.

They both quote RMS.

There is some heavy stuff inside the Luxman. JVC is stretching their watts by a long way and the amps from Japan made when the Luxman was probably were very conservatively rated.

If you are looking for a nice solid state amp the "heavy iron" vintage Japanese units are hard to beat sound wise and price wise and I think Luxman is one of the best.

[goraman]

I thought the same thing are watts really watts.

I bought a JVC 7.1 receiver from Frys Electronics on sale for $110.00 and thought this marvel puts out 110 watts per channel.

I connected it to some Advent speakers, not the most efficient but not that hard to drive.

I would usually have the volume just over half way to get the desired level in two channel stereo mode.

Then I happened across my now main amp the venerable Luxman L-430 rated at 105 watts per channel.

I hooked it up to the Advents and if I even attempted to turn in up to half way I would be in danger of stripping the paint from the walls.

Hmmm somethings fishy here.

Now the Luxman weighs in at almost 30lbs the JVC half that.

They both quote RMS.

There is some heavy stuff inside the Luxman. The JVC is stretching their watts by a long way and the amps from Japan made when the Luxman was probably were very conservatively rated.

So my advice is you are going for a nice solid state amp the "heavy iron" vintage Japanese units are hard to beat sound wise and price wise.

The heavy stuff is iron,a real transformer,the new av stuff of cheaper means use switching power supplys and don't weigh much.

was the RMS into a 2 ohm load ? read further another modern trick.
but a RMS watt is an RMS watt into the same load.

[giorgino]

:lol: I like the analogy!

It sounds like you have bought the american equivelent of a Volvo estate, probably quite a small car over there?
The mums over here drive the big off road cars to get the advantage you have bought for your wife!

My amp is 1.5W (triode mode) 3W (ultralinear mode) so I guess mine's the equivalent of a go-kart....:lol::lol:
Having said that, it should still be capable of 105dB peaks.

[The Vinyl Adventure]

sony do indeed quote rms figures

sony chav-fi

http://i728.photobucket.com/albums/ww282/hamish_gill/4bcc74fa.jpg

380 watts rms

http://i728.photobucket.com/albums/ww282/hamish_gill/aee4e3dc.jpg


sony dav-dz280

http://i728.photobucket.com/albums/ww282/hamish_gill/9542e907.jpg

850 watts rms

http://i728.photobucket.com/albums/ww282/hamish_gill/f64c4142.jpg


?????

[HighFidelityGuy]

Total power is the figure obtained after adding up all of the power outputs of all the channels. It a fairly pointless figure. So for a stereo amp you would have to half the value to get the Watts RMS per channel rating.

Also, note that the rating is taken at 10% THD!!!
THD is Total Harmonic Distortion. A quality manufacturer would quote it's output power around 0.05% THD or lower in some cases. That's for a solid state amp. Valve amps have a THD figure that's higher but that can't be compared against solid state amps as they produce different types of distortion. :)

[HighFidelityGuy]

So basically that AV system will produce 142W RMS into it's main channels when pushed so hard that it runs into distortion. You really would't want to replicate those test conditions at home as it would probably damage the speakers and sound shite.

[The Vinyl Adventure]

i know its marketing nonsence, but its a stupid thing to get involved in on sonys part i think, its misleading and creates confusion

[HighFidelityGuy]

As an example, my mono blocks are rated at 550W RMS when driving an 8 Ohm load.
The THD figure is measured over the full frequency range of 20Hz to 20KHz to be <0.016%. So they can produce 550W over the full audible frequency range with distortion much lower than 1%. Compare that against that bottom Sony amp's 142W at 10% distortion and you start to see how much better quality you get for the extra dosh. I can use the full power of my amps without any detriment to the sound quality, the Sony amp will distort the signal long before it reaches it's rated power.

The average Joe on the high street won't know what THD means and will just look at the power rating and think bigger is better. :)

[The Vinyl Adventure]

i know it stands for total harmonic distortion :) ... thats about it though...
i can see that a large figure on paper should be worse but from the little snippets i have read about this place its not as clear cut as that.... christ, sometimes i wonder if i deserve to own such a snazzy valve set up :o

[MartinT]

I simply wouldn't believe that Sony figure of 850W RMS (did you notice the 10% THD - Jeez, that would sound nice), those speakers would *melt* if that power were truly put through them.

I remember I used to call PMPO or whatever 'Amstrad Watts' for the lies they were telling with regard to output power. Most computer speakers are equally stupidly rated, even small ones being '100W'.

For Jeff & Kris: maybe the best analogy is torque being a better indicator of a car's real-world performance than horsepower. I used to have a BMW 540i with a 4.4l V8 engine pushing 286bhp in standard trim. I now have a BMW 335d Coupe with a 3.0l twin-turbo diesel engine pushing, co-incidentally, 286bhp.

I had both remapped for more power and they both have similar weight so the comparison is quite fair. Which one's faster? The telling figure I haven't given you is their torque. The 540i gave about 450nm peak torque, the 335d gives 700nm. Not surprisingly, the 335d is brutal and leaves the 540i for dead.

So maybe valve v transistor power should be compared with torque rather than horsepower, in the sense that valve amps more efficiently couple their power with real-world speakers.

[REM]

There is some further discussion regarding amplifier power and its relevance to the real world on the ATMA-SPHERE (http://www.atma-sphere.com/papers/paradigm_paper2.html) site.
Some other interesting observations regarding toob v trannie amps in some of the other 'papers' as well.

[twelvebears]

Only RMS watts count. All others are imaginary!

Dave

Indeed! I laughed myself silly at The Gadget Show last night went a £380 all-in-one bluray/amp/speakers set-up was described as having '1000watts of music power' :lolsign:

[Hypnotoad]

In comparing say a McIntosh putting out 380w to the Sony.

It would be like being hit by a freight train compared to a mosquito at the same speed.


From the McIntosh website:

Power Amp Distortion Max.

20Hz to 20kHz Both Chan Operating at Rated Power = 0.005%

A good bit better than Sony's 10%

[The Vinyl Adventure]

In comparing say a McIntosh putting out 380w to the Sony.

It would be like being hit by a freight train compared to a mosquito at the same speed.


thats funny, the sony sounds a little like a mozzy ... you know when they get right in your yug hole and buzz about....

[Themis]

"Total output power" means nothing at all. It's a marketing thingy.
Only 1 channel output power counts (here 145w) and without knowing the speakers' efficiency, this means nothing either.
And this figure with 10% of distortion is completely meaningless.

In other words, it's all bs.



To come back to efficiency and watts: Every speaker has two caracteristics: efficiency and maximum power.
If you draw a line in the picture that follows, that joins the maximum power (left column) with its efficiency (center column) you get a maximum SPL the speaker can give.
Or, if you join the amplifier's maximum power (provided it is lower that the speaker's one) with the speaker's efficiency you get the maximum SPL of the amplifier for this speaker.
A good SPL is at least 110 SPL.

http://www.son-video.com/Conseil/Hifi/Images/AbaqueSensVide.gif


For instance, you need a 2x100w amplifier to get a good SPL from the Evo3's:
http://www.son-video.com/Conseil/Hifi/Images/RendementAegis3.jpg

[Alex_UK]

For instance, you need a 2x100w amplifier to get a good SPL from the Evo3's:

Looks like I need to go amplifier shopping then! ;)

[Jonboy]

it won't stop there though will it Alex, you know what i mean the upgrade itus will start, that itch will need itching:eyebrows:

[The Vinyl Adventure]

Hey alex have you heard about these glowy glass bottle things ... ;)

[goraman]

Hey alex have you heard about these glowy glass bottle things ... ;)


Oh, you found my urin samples...
Do you guys have Rock Star energy drinks there?
Drink one your pee glows in the dark,drink 2 and you can power a small reactor.

[The Vinyl Adventure]

Ha, sounds like baroka to me - orange energy pills make your toungue tingle and you piss radioactive

[markf]

"And my 40wpc valve amp has much more oomph than my naim nac180 did and they are 90wpc"

Hamish,
I think most Naim amps are quoted for driving into 4 Ohms, so the NAP 180 is
90 watts per channel into 4 ohms ,which would be 45 watts into 8 Ohms.
Your tube amp and the Naim you had have similar power.

[The Vinyl Adventure]

Yeah that sounds more familiar... Point still stand though the new kit has much more oomph