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Is a watt is a watt is a watt?

Discussion in 'Amps and Cabs [BG]' started by CaptainWally, Jan 21, 2001.

  1. Somone tried to tell me that English amplifiers
    give more power for their ratings because English
    watts were different than "American" watts.

    Example: An Ashdown 300 actually gives over 500
    "American" watts. (Ashdown is made in U.K.)

    This sounds like bullocks to me, but I've been
    known to have gaping holes in my wordly perceptions.
    I thought a watt was a watt - international unit.

    Am I iggernant?
  2. A watt is a universal measurement, and whoever told you that was, as I say, Full o' Bull.

  3. yup, a watt is definately a watt, period.
  4. NJXT


    Jan 9, 2001
    Lyon, FRANCE
    Yep, a Watt is a Watt ... BUT it doesn't really give you the sens of the volume you'll get out the amp. Depends on so many others factors : are they measured in RMS watts ? Din Watts ? In "mesuring method recently Made up in the mind of the maker" watts ?
    People (me first) often refer to volume when talking in watts. But 100W amps can be louder thant a 200W one.
    Perhaps that's what your friend meant about ashdown. It depends on speaker efficiency and that sorts of things ...
    Look at guitar (sorry) amps : a 40W Fender Hot Rod Deluxe (Tube) is so much louder than a 80W Ross (Tube).

    [Edited by NJXT on 01-21-2001 at 02:39 AM]
  5. Matthias


    May 30, 2000
    Vienna, Austria
    A watt IS a watt - everywhere. (no difference like between statute mile (UK) and nautical mile (US))
    But i've read in another thread, that in the 60ies US manufacturers used 'peak to peak' ratings and UK manufacturers used RMS ratings called 'British rated watts' - or the other way round, I don't know. Meanwhile all serious companies use RMS ratings.


    [Edited by Matthias on 01-21-2001 at 08:42 AM]
  6. There are three ways or more ways to rate watts, the watts remain the same but the tests change. Rms puts one note, a sine wave and mesures how much power you use on a continous bassis with a low amount of distortion. Continous, music power ect type of mesurement put in a signal that represents music playing (more than one note) At a low amount of distortion. Peak mesures trancient response or a very short burst. This could be to the point of the actual point of destruction of the device. All of these mesurements look different on paper. What we are looking for is how loud the thing is or how it cuts through the mix. Only a good revue by a bassplayer can tell us this.
  7. nanook


    Feb 9, 2000
    To make matters more complicated, a tube watt is different that a solid state watt. Not mathmatically but definately in sound.

    Limey amps are designed to run on 50 cycle power rather than 60 cycle (North American) power so the same amp might put out different watts depending on where you plug it in.

    You need to ask Pysco obout this.
  8. Oysterman


    Mar 30, 2000
    Isn't this because when you overdrive a tube amp, and the sound gets compressed and that gives the impression of higher loudness?

    And you don't get this effect with SS amps, right? Anyway, overdriven solid-state amps just sound plain awful.
  9. Right on the money, Psycho (of course)! A lot of pro audio guys (like me) are pushing for standardized tests (ie ISO standards) for all audio equipment, especially for power amps for those very reasons. Lesson: Take all manufacturer's specs with a grain of salt, never buy an amp sight unseen. :D
  10. Another thing... my SWR SM400S is not 400 watts, it's 500. A Gallien Krueger 400RB is not 400watts, it's 200. Manufacturers do not always designate the power in the model name.
    Spacegoat, or any of you techy guys, can you tell me what EAS ratings are. How do they compare to RMS? ( I know what RMS ratings are). Some old vintage amps are rated EAS.
  11. Mr.Ben


    Jan 16, 2001
    Long Beach
    Most modern manufacturers of amps (SWR in particular) are notorious for claiming that they are overly modest in their products (claimed) power. SWR changing the SM 400S's name (now the 500S) is a clear example of this marketing ploy. I have owned an early version of this amp and with the exception of some minor front panel additions and a fan the unit is relatively unchanged for approx 15 years. Furthermore for an amp rated at 500 watts it is dissapointingly weak, even if they didn't change the name.
    I believe that for the consumers (us) there should be a standardized testing procedure and a standardized scale for loudess in musical applications, say a scale of 1-20 that all manufacturers, if they wanted any credibility, would apply to their products. That would up the competition.
  12. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    Please, please stop passing along this MYTH. As you say mathematicaly, it IS the same, to get one watt you drive a potential of one volt with a current of one amp, period. Soundwise, well if you feed a 1 KHz sine wave in and generate an output of ONE WATT most amps will sound about the same, period, whether it's a Rogue or an Aguilar.

    When people are concerned about wattage relative to VOLUME they overlook the fact that RMS rating are measurements of continuous sine waves, i.e. a test tone. Music has dynamics to it and dynamic response is important. Two identical RMS wattage amps can sound a lot different when fed with dynamic signals based on the SHORT TERM power capability of each amp. In some cases the amp with LESS short term power can sound louder because of compression and distortion effects but this has NOTHING to do with the WATTAGE.

    So a watt IS a watt IS a watt.
  13. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    Here's a real problem we have, how loud should a 500 watt amp be.

    Mathematically, 3 dB increase in volume is achieved by doubling power (in watts). 3 dB is generally coinsidered the smallest NOTICEABLE change in volume humans can easily detect. That means between a 200 and 400 watt amp (all else equal) you should be able to just barely detect the 400 watt amp as louder. In any event, it won't seem much louder.

    TWICE as loud is an increase of 10 dB which requires TEN TIMES the power. So a 400 watt amp is twice as loud as a 40 watt amp, all else equal.

    When upgrading amps to get more volume it's ridiculous to go for less than a FOUR time increase in wattage otherwise the change will be barely noticeable. That is if your 100 watt amp doesn't cut it, better shop for 400 watts not 200.

    Now let's get back to why the 500 watt amp isn't "loud enough". Believe it or not, to make an amp seem louder all you have to do is boost the midrange. Go take whatever amp you are using now and try this:

    -- Boost the mids
    -- Cut the mids

    -- Boost the lows the same amount as you did the mids
    -- Cut the lows the same amount as you did the mids

    Guess what, the adjustment of the mids has a MUCH BIGGER effect on how loud the amp seems. Another good example is adding subwoofers to a PA, it has the "chest pounding" feel but doesn't seem to make the system much louder.

    So if you take an amp that has a strong midrange emphasis (i.e. Ampeg) and compare it to an amp with less mid emphasis (i.e. SWR) guess which one sounds louder, watt for watt!
  14. Brianrost,
    you couldn't be more right! Everyone should read and internalize your last posts! Our perception of sound is often more important than power ratings, when it comes to amps. If you have two of the same amps, one with mids cut and lows boosted and the other opposite, set up so that they produce the same Sound Pressure Level to a Decibel meter, the one with the mids boosted WILL sound considerably louder. That's because our ears are much more sensitive to mid frequencies than to bass or treble. This is a measureable effect. It was measured and documented in the 40's by two guys named Fletcher and Munsen. Hence, the Fletcher-Munsen equal loudness curve. The differences in power are incredible. for example, a 100 Hz tone would need to be 140 dB to seem equally as loud as 1 kHZ at 100 dB. That's 10000 times as much power!!! all other things equal. Don't get me started on short term power capability..:D Let's just say that transient handling ability increases in direct proportion to the weight of the amp (switching power supply vs conventional PS). As for tube amps vs solid state amps: Tube amps will invariably APPEAR louder than SS amps of the same power. As you said, this is NOT a function of wattage it is mostly a function of our perception of sound!
    Adding good subs to a PA can actually allow you to have a quieter mix (to a meter). Adding low end increases the impact of the sound without increasing spl. Low frequencies actually make your body release endorphins! That's the real reason we all play bass:D:D:D .mmmmm, endorphin buzz... There is an increasing number of audio professionals that are trying to extend the low frequency spectrum in order to bring the overall Spl of concerts down in order to minimize hearing damage. Holy rant! I only meant to quickly echo Brianrost's post and I've written a novel!
  15. VicDamone


    Jun 25, 2000
    It's true! English stuff is more powerful. That's why the Who could play so loud, the English watt at 50 cycles is a killer. You think they drive on the other side of the road just to be different? NO. English rock bands play way loud and their audiences all have this little hearing thing in the right ear. You've heard of the saying, "turning a deaf ear?" Well... that's an English saying.

    I know there are some Brits on this site who can straiten this whole thing out. Better yet the Irish are excelent at explaining this phenomena.
  16. MikeyD


    Sep 9, 2000
    LOL! :) Good one, Space! I'm interested in reading about this. Do you have a reference you can cite?

    I haven't noticed that yet! (Last George Clinton P-Funk concert I was at was unmitigated ear-bleed.) Probably most of the damage occurs in the upper frequencies, so it would probably be preferable to knock those down a bit. Interesting comment, though.

  17. oops, I misquoted a little in my last post. 100 Hz actually has to be 20 dB louder than 1kHz to be at the same apparent level, not 40. This is still very large difference. Sorry bout that.
    Mike, there's a real good article here: http://www.livesoundint.com . Go to the link called "audio insiders" the article is in the february 2000 issue. The whole article is online. It was written by the President of Servodrive. They make these crazy servo motor subwoofers (no voice coil). Any sub that can produce 140dB at 28 Hz has got my respect!! I've used rigs with these things and they are absolutely incredible. Sternum crushing low end!! The trend toward lower mid/high SPL and extended LF is far from widespread, but it's growing. Mixing and producing sound with respect to the Fletcher-Munsen curve is a great idea.I saw April Wine in a 1000 seat club last weekend and it was absolutely deafening...thank God for plugs!!
    Oh, I just found out today that the chapter of IEEE (and the Faculty of Engineering) at my school is in the process of building an audio research lab complete with an anechoic chamber! woohoo! I can't wait to get in there. Got to get through this term first....holy workload, batman.:D
  18. MikeyD


    Sep 9, 2000
    Thanks for the correction. It didn't seem right to me before, but I was too lazy to get my books to check.
    Thanks for the link and directions to the article. Looks like a good web site. The article looks really interesting - I'll read it as soon as I can (it would've been nice to get the article in .pdf format, though). Yeah, I looked at ServoDrive's web site awhile ago - an interesting concept. EAW also sells some horns that are capable of that kind of effect at low frequencies (or so they claim).
    Yeah, it makes some sense. But live sound venues may have more headaches to deal with in terms of annoying neighbors because of the way low bass diffracts around obstacles and passes through barriers.
    That's great! My undergrad engineering school (U. of Hartford) had an acoustics lab with an anechoic chamber, too. It was great to have access to it. Sounds like you're going to the right school - and the hard work means you're getting your money's worth! ;)

    - Mike
  19. LvHooters


    Sep 20, 2000
    WATT weighs more...a Pound of Feathers or a Pound of Gold?
  20. Before you all race out and sell your 500watt amps and downsize to 50 watts 'cos the volume's not much different, remember that to get a B string to sound good you really need minimum 300 watts, preferably more, and God only knows what it takes to make John Turners low F# ring out. Power is not about volume, it's about tone!

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