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Comparing these specs on a receiver and speaker.

Discussion in 'AV Receivers' started by darsunt, Oct 29, 2012.

  1. darsunt

    darsunt Member

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    I'm looking at a Denon av unit with these specs:
    95W X 3 front speakers, 95WX 2 rear speakers, 95 W per channel
    And these speakers:
    Polk: 20-150W/channel
    Definitive: 10-175W/channel
    So since the av unit is only 95W for channel, is it inadequate because it doesn't equal peak wattage use for the speakers? It doesn't seem right to me because the speakers are in a moderate price range ($200 - $300) and the denon av I can find that has 150W per channel is priced at $2500, that's a huge price differential.
     
  2. schan1269

    schan1269 HTF Expert
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    That receiver is only going to produce half that(even that is a maybe) with 5 channels going at once.
    Power ratings on speakers are useless as well.
    You don't buy speakers based on "wattage". You buy them based on YOUR ears, ohm load and efficiency.
    Also, when it comes to power, in most rooms, ear splitting concert levels of volume are achieved on 20wpc.
     
  3. darsunt

    darsunt Member

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    Yes what I read about watts and speakers is very confusing. The salesperson at Best Buy told me comparing power output in watts was everything, but can you trust this salesperson?
    What I am concerned about is I read you can damage speakers if they are underpowered. But awhile back I bought an old definitive c/l/r/ 2002 center speaker (rated 20-250 watts) and paired it with an ancient old amplifier, haven't damaged the speaker yet (I think).
    All the speakers I am looking at have sensitivity of 90-91 dB and nominal impedance of 8 ohms (good I think)
     
  4. darsunt

    darsunt Member

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    I would like to try out the receivers and speakers of course, but at Best Buy they have only their top of the line stuff in their listening room. I don't know anyone else around here with much home theater stock, so buying by hearing is not a practical option.
     
  5. Steve Schaffer

    Steve Schaffer Well-Known Member

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    those appear to be fairly efficient speakers and should be easily drivable with most inexpensive receivers. It might help if you post the model number of the particular receiver you're considering. Wattage ratings on receivers are pretty useless--you need to know what the parameters are for the rating.
    For example those cheap plastic box HTIB systems are almost always "rated" at 1000 watts or more--into 3 ohm speakers at 1khz with 10% THD (Total Harmonic Distortion). This is totally inflated. The lower the speaker impedance (measured in ohms) the higher the wattage number will be, also the 1khz means the wattage is being measured with the amp producing a steady 1000hz tone--very easy (it's the low bass that consumes wattage), finally, the higher the allowed distortion (THD) the higher the wattage rating will be.
    Typically power ratings for higher end receivers will be into an 8 ohm speaker, at full frequency range (20-20,000hz) with THD down around .07%.
    If you measured the power from that plastic box HTIB at those parameters you'd probably get 10-15 watts or so. (Schan can correct me on this)
     
  6. schan1269

    schan1269 HTF Expert
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    About "clipping" (which is the term for "asking too much from your amp")...
    Any amp will power any speaker(when comparing amps meant for speakers you are actually going to be be buying...IE, you don't buy PA amps to run home speakers, just like you don't buy a home amp to run PA)...
    The OHM load, in reality, only matters for when you turn the volume up past the "comfort level" of the amplifier.
    Take an AVR capable of 50wpc x 5...
    At 8 ohm, it creates the 50x5. At 4ohm, it theoretically, will create 100x5. It won't actually get there though...however...
    Movie soundtracks don't push all 5 channels at the same rate, so you could have the 5 channels pumping along at 30/45/20/25/15(total of 135)...That amount of power is going to make you go deaf...and have your neighbors complaining.
    What happens at 4ohm vs 8ohm...
    A given amp(no matter how many channels) has X amount of power it can produce. It is designed to keep that amount of power production cool. When you "halve the OHM load", you reduce the gain required to get your amp there...
    So, an 8ohm speaker might require 80% gain* to achieve "maximum output"...
    A 4ohm speaker would require roughly 50% gain* to achieve the same "maximum output"...
    That is how you fry/kill amps on 4ohm speakers...taking it beyond its comfort zone.
    *and about "gain". You'll see AVR that mention "4ohm capable"(such as Onkyo)...they will even have a setting for 8 or 6(sometimes 4)ohm.
    All that setting does, is curtail the gain so that at 8ohm, the AVR lets you have 100% gain. At 6ohm the AVR lets you have 75% gain. At 4ohm the AVR lets you have 50% gain...
     
  7. darsunt

    darsunt Member

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    Here are some denon receiver models I am looking at
    AVR 1713
    AVR 2113
    These seem like reasonable quality receivers, and I gather from what you guys are saying it is unlikely they will damage any of the speakers I am looking at unless they are cranked way too loud.
    I don't recall any receiver literature stating the conditions under which the watts per channel were obtained. I will try to download some manuals to see if they go into such detail.
     
  8. schan1269

    schan1269 HTF Expert
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    Denon rates their AVR like "most" do(Sherwood and HK being the notable exceptions)...
    With two channels running at a time...then they "claim" that x 5/7/9/11(whatever the AVR is...5/7/9/11 channel)
    They will say, on the box, 85x7(throwing a number out there cause I don't care to look up the specifics of the 17/2113)...even though the reality will be closer to 45x7.
     
  9. gene c

    gene c Well-Known Member

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    Those are both very good entry to mid level receivers.
    If you want to see what the actual power outputs of receivers are check Hometheaterhifi.com, Hometheatermag.com or S&V.com to see if they have done a review with bench test of a particular receiver. Here's a HomeTheater Magazine review and lab test of a Pioneer 1019. Pioneer rated it at 90 wpc x 5, some literature suggested 110 wpc x 5 but HTM bench test came out as 29 wpc x 5 @ .1% thd. http://www.hometheater.com/content/pioneer-vsx-1019ah-av-receiver-ht-labs-measures It also tested at 108 wpc in stereo (X 2).
    But it would still be more than powerfull enough for 90% of us. As was said earlier, look at ohms and SPL when buying speakers and forget about the power ratings.
    And just to clarify the thought of damaging a speaker with too little power, what they mean is an amp the goes into clipping at low volume. Suppose you give your speakers 25 watts of power from an amp that produces 50 watts of clean power. All will be fine. But suppose you push 25 watts out of an amp that can only produce 15 watts of clean power (even if it's rated 50 watts @ 10% thd). Then the amp will probably go into "clipping", producing a great deal of distortion. It's this distortion that damages speakers, not too much power. So in effect, you have damaged your speakers by under-powering them. Not with too little power but with too much distortion.
     
  10. Jeff Leeds

    Jeff Leeds Well-Known Member

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    And you should note that the pimple-faced kids at Best Buy know about as much about the produsts as my Golden Retriever.....they just echo whatever the 25 year old assistant manager told them in their "training"....these are people who were asking if you "wanted fries with that" or "leave room for milk" at their last job. Great place to buy a new clock radio or pick up a discounted BR disk, but not anything more.
    It is too bad you do not have any other place to buy this type of thing, Sears is frankly a better place than BB.
     
  11. Steve Schaffer

    Steve Schaffer Well-Known Member

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    ^^^but Sears doesn't sell much in the way of receivers. As for the sales personnel it varies but there's usually one or two on the floor that actually know about the products.
     
  12. darsunt

    darsunt Member

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    I don't believe Sears sells surround sound receivers.
    I did find one audio specialty shop in Seattle during my vacation. Cool stuff, but extremely high end, out of my league right now.
     
  13. Steve Schaffer

    Steve Schaffer Well-Known Member

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    ^^^I work there, we only sell one. Where I live (Fresno CA) there is actually only 1 B&M store with a halfway decent selection of realistically priced receivers and that's Best Buy. I'm not averse to buying there but will do my own research beforehand.
     
  14. Jeff Leeds

    Jeff Leeds Well-Known Member

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    Try B&H online, great service, no taxes, and no pimple faced kids.
     

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