Amp rating and loudspeakers

Discussion in 'AV Receivers' started by Pesiba, Nov 14, 2003.

  1. Pesiba

    Pesiba Extra

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    Okay, there's something that baffles me and would like an opinion. I've heard that its' best to use an amp with a power rating that exceeds the loudspeakers' to ensure that the latter doesn't clip. I know that most people have HK a/v receivers with power ratings of say 45 wpc (4 channels) powering 175+ wpc loudspeakers and have expressed how well the HKs perform.

    My question is: which is the best, an amp with a lower amp rating than the loudspeakers or one with a higher power rating?

    Pesiba
     
  2. John S

    John S Producer

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    There is never enough power period. The more power the more head room, the better it will all sound.


    You should not be grossly over the speaker rating or you will blow it, even without clipping. You can save the speaker a lot of grief if you set the cross point much higher, I used to run mine at 120hz before I upgraded my speakers, becasue my old ones, I just didn't trust, even though they had what would be considered usually a safe rating. But lower end even half decent speakers lie like crazy. The higher end you go the more truthfully accurate the rating becomes.
     
  3. John Garcia

    John Garcia Executive Producer

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    The wattage rating for a speaker has to do with one or more components in the crossover that are rated to safely handle that much wattage before they fry. This has NOTHING to do with how much power you SHOULD feed the speaker, so you can all but ignore a speaker's power handling rating. Delivering a CLEAN 45w to them should cause no problem at all.

    Speakers are not typically damaged by too much power, but too little. If you clip the signal by having too little power for the SPL with a given speaker, you can quickly damage the speaker.
     
  4. Michael R Price

    Michael R Price Screenwriter

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    "Speakers are not typically damaged by too much power, but too little."

    Or rather, too much power delivered at the wrong frequencies because an amp was not strong enough to deliver that power at the right frequencies.
     
  5. Jerry Parker

    Jerry Parker Stunt Coordinator

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    Call me crazy, but could it be that loudspeakers presumed destroyed by clipping not because of the clipping itself, but the fact that an amplifier that is clipping fully can produce close to 3dB MORE power output than when its not clipping? [​IMG]

    http://www.rane.com/pdf/note128.pdf
     
  6. Pesiba

    Pesiba Extra

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    Pardon my ignorance. John, what do you mean by CLEAN 45 watt power? Also, which is more important, an amp with high current capability or wattage?

    Just to add to this: when HK quotes the current capability of their amps as +/- 35 A, does this imply that all five channels can output 35A equally or just 7 A per channel.

    I'm just trying to understand a little bit more so I can make an informed purchase when I get to upgrade my stereo system. Thanks for the responses so far.

    Pesiba
     
  7. keir

    keir Stunt Coordinator

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    what is meant by clean power is that is can deliver the power without becoming audibly distorted. a good quality amplifier should deliver its rated power at a low distortion level.

    high current implies more wattage. a good amplifier will be able to deliver a higher current before its power supply becomes overtaxed. HK and others go out of their way to make sure the power supply is robust enough to handle a high current demand. this is especially important when the speaker's impedance is lower than the normal nominal 8 ohms.

    really the important thing when buying an amplifier is the brand. i would go with a respected brand like HK. there is no question that HK or similarly good brand will be able to adequately power nearly any speaker. an HK rated at 45 watts per channel is still giong to deliver much, much higher power at much lower distortion than the panasonic at best buy rated at 100W x 5. going by specs alone is difficult even if you're knowledgable about electrical engineering, because the companies don't disclose enough information to really make the specifications meaningful.

    no amp is going to put out 35 amps to each channel. the spec probably means it can deliver 35 amps total for a very short time during high dynamic peak in the program material, which is an impressive number for any amplifier.
     
  8. Pesiba

    Pesiba Extra

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    Thanks a million for the explanation.

    Ppesiba
     

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