Amp and Speakers power ratio

Discussion in 'Beginners and Audiophytes' started by OmniDir, Jan 31, 2013.

  1. OmniDir Audiophyte

    OmniDir
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    I am about to upgrade my system. A salesperson at a very respected audiophile store is recommending me an amplifier that has only 3/4 the nominal power compared to that of the speakers that I am looking at. He says that as long as I don't intend to play at crazy levels, it won't be a problem. Is he correct?

    Store: AudioConcept in Stockholm, Sweden
    Amplifier: HarmanKardon BDS277 - 65 nominal watts at 8 ohms
    Speakers: Grundig Audiorama 9000 - 120 nominal watts at 6 ohms​

    Everywhere I turn for advice, I am presented with the rule of thumb 2:1 ratio (amp:speakers) for nominal power, with warnings that a too weak an amplifier might damage the speakers. (The amp/speaker combo I'm being recommended roughly has a 3:4 ratio)

    My question is this:
    Does the 2:1 power ratio apply only at amp clipping levels? Or is important also when playing at moderate levels?
  2. Irvrobinson Audioholic Ninja

    Irvrobinson
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    The ratios are meaningless, mostly because speaker power ratings are meaningless. What matters are the sensitivity and efficiency of the speakers, how large the room is you want to put them in, and how loud you want the sound levels to be. How big is your room?
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  3. twoeyedbob Audioholic

    twoeyedbob
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    Basically any amp can damage any spkr's...if the operator
    Has no idea what distortion sounds like...or is deaf.
    Most manufacturers measure power in different ways
    Therefore making it nigh on impossible to work out these ratio's.
    High end stuff is usually measured properly..making it look like
    It hardly produces any power

    Whereas cheap s**t usually has 2000 WATTS splattered all over the box ,..while actually producing nearer 20 watts.
    Basically ....most of these numbers are pretty meaningless.

    Expensive,heavy amp with small cheap spkrs...bad
    Cheap,lightweight amp with big expensive multidriver tower's..
    Also bad

    From a quick glance your stuff doesnt look likely to
    Cause any problems...whether it sounds any good is another matter

    Sent from my HTC Vision using Tapatalk 2
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  4. markw Audioholic Overlord

    markw
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    If you can't impress 'em with brilliance, baffle 'em with bulls**!

    That's the credo that salesman lives by. His quote "He says that as long as I don't intend to play at crazy levels, it won't be a problem." is correct, but it has nothing to do with his self imposed ratio.

    Any amp can damage any speakers if one is stupid.

    You can have a high powered amp with low power rated speakers or a low powered amp with high power rated speakers.

    All you have to do is listen and use your head.

    If it starts to sound bad, distorted, funky, or in any way abnormal, turn it down immediately. That's the sound that something is not happy.
  5. j_garcia Audioholic Jedi

    j_garcia
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    Can we just make this a sticky or a tip of the day? This one seems to need to be answered at least twice a week.
  6. twoeyedbob Audioholic

    twoeyedbob
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    Good idea...although from previous experience...it'll still be
    Asked twice a week :-(

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  7. OmniDir Audiophyte

    OmniDir
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    The room is approx. 40 m2, ceiling is about 2.60 m.

    The system will serve both tv/movie watching and music listening. We will be in stereo the sweet spot only when watching tv. But we listen to music a lot also sitting at the dinner table or cooking in the open kitchen. This is why I opted for the omnidirectional Audiorama speakers.
  8. j_garcia Audioholic Jedi

    j_garcia
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    40m? That's a big room. Even with a very sensitive speaker, that is going to be hard to fill with 65W, however if you are only interested in average listening levels, it will likely be sufficient.
  9. twoeyedbob Audioholic

    twoeyedbob
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    Most av amp's have the option of a second zone
    Surely a Better idea than compromising everything else
    ?

    Sorry if i'm mistaken ...not sure what you have available in sweden...but £899 (uk price) for effectively a
    Entry level bluray/2 channel (65watt max ?) receiver ....seems a vast amount of money
    I would also be concerned(given they're design) that the spkrs will be particularly low on bass output
    Also,.. the effect '360 degree sound' will have on any sort of imaging..or 'sweet spot'
    Combine this with a fairly large room......


    Not good..imo
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    Last edited: Jan 31, 2013
  10. Irvrobinson Audioholic Ninja

    Irvrobinson
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    That's not so big, about equivalent to 21ftx20ft (430 sqft) for those of us with a metric aversion. 65W should be okay. I don't think those speakers will play all that loudly with reasonable distortion anyway.
  11. ImcLoud Audioholic Ninja

    ImcLoud
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    I would want at least 1700 watts in that room... :) then it wont matter much which speakers you have.. My HT is 1350 watts, and my 2.2 system is 1200 watts, there is nothing wrong with a ton of power..
  12. Bryceo Banned

    Bryceo
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    I'm with ^^ on this one a tone of power makes for any kind of sittuation :)
  13. OmniDir Audiophyte

    OmniDir
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    The speakers play very well, and fairly loud (I've only heard them with a powerful amp). I guess that the omnidirectional design is a love/hate thing: it obviously compromises the possibility to have a real sweet spot, it does on the other hand allow for good sence of direction and space from a lot of listening positions.
  14. OmniDir Audiophyte

    OmniDir
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    Back to my original question:
    Is the need for amp power headroom important only at clipping levels, or is it important at all playing levels?

    Additional: assuming that bass frequencies require more power that mid or treble; would the adding of an active subwoofer (might be required for these speakers) take some load off of the amp, allowing it to play the speakers louder without distortion/clipping?
  15. twoeyedbob Audioholic

    twoeyedbob
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    Yes...the design (cabinet size) of these spkrs is such that bass will be limited ,add that to the room size and the relatively low
    Power of the amp....
    I'd suggest a decent sub is a must




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  16. markw Audioholic Overlord

    markw
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    As to your original question, your speakers should be safe fed their maximum rated power in CLEAN, UNDUSTORTED, NON-CLPPiNG watts for an as yet unstated period of time. Your manufacturer left out the part about whether it's peak or continous watts they are talking about.

    Also, keep in mind that while try might be able to withstand those watts there is no guarantee they will sound good while doing so,at least forany length of time. Lotsa watts generate lotsa heat which tends to melt things like voicee coils.

    On the posoiitive side, most listening is done at a relatively low power. It's only the peaks that are a major concern.
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  17. j_garcia Audioholic Jedi

    j_garcia
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    Sorry, automatically thought 40m square (40mX40m), because that would be a massive area.

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