signal to noise ratio

Discussion in 'AV Receivers' started by Daryl_hawk, Sep 27, 2004.

  1. Daryl_hawk

    Daryl_hawk Agent

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    Would someone be able to explain this to me as it pertains to receivers?? I have been looking at some receiver specs and noticed snr's of 102 100 and 95 between Denon and HK but don't now how to interpret the numbers. Do small differences like that matter?

    thanks
     
  2. Chu Gai

    Chu Gai Lead Actor

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    The SNR spec on an amp or a receiver for that matter tells you how much noise the device is putting out. Manufacturers specify it according to some reference level. For example in a receiver or an amp, its specified according to the rated power.

    As a spec, the SNR is pretty useless, but its easy to measure and trot out. The reason why its useless largely has to do with its a single number and doesn't specify what the frequency distribution of this noise is. For example, lets look at two hypothetical receivers with identical power and identical SNR's. If the noise spectrum of one amp is concentrated in a narrow band at say 2kHz while the other is concentrated above 15 kHz, then at high levels you likely couldn't tell one apart from the other. Take a situation though where you're listening to low levels or with highly efficient speakers, one will sound notably different.

    Let's assume though that the broad band distribution of noise is the same though and look at three hypothetical receivers, all of which have 100 dB of SNR.

    The 50 wpc will have 200 microvolts of noise.
    The 100 wpc will have 280 microvolts of noise.
    The 400 wpc will have 560 microvolts of noise.

    Therefore, assuming one is listening to low levels with high efficiency speakers, where the receiver isn't putting out a lot of volts, maybe, just maybe you might hear a slight hiss if you go close to the speakers. Maybe.

    I'd not let this one spec guide your decision and instead focus on whether the receivers meet your needs in terms of functionality, expandability, ergonometrics, warranty, availability of service, sufficient power to drive your speakers to the levels you're likely to listen at, and so forth.
     
  3. Daryl_hawk

    Daryl_hawk Agent

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    cool, thanks for the info. I am still not 100% clear but am I right in assuming that it basically has to do with the likelyhood of hearing something in the background.....the lower the greater the chance???

    So SNR has nothing to do with the dynamic range of the sound then right???
     
  4. Chu Gai

    Chu Gai Lead Actor

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    If we're talking the same wpc rating and assuming the noise distribution in both receivers is the same, then yes, a 100 dB SNR spec means the noise floor is lower than a 90 dB SNR. I'm not sure where you're going with this dynamic range though. Ultimately, if you're playing CD's, the dynamic range is dictated by how the CD was mastered. I've got a feeling though, that's not what you're really interested in.
     
  5. Daryl_hawk

    Daryl_hawk Agent

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    i'm just trying to get a handle on what it all means. I currently have a Denon and am debating about upgrading......another denon model and a HK had different SNR's (Denon 102 @ 100wpc and HK 95 @ 75wpc) and I was curious if the HK was inferior in this regard....
     
  6. Wayne A. Pflughaupt

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    Personally I think S/N ratios are a very important spec, but as Chu notes it’s somewhat compromised because manufactures don’t use a uniform method or unit of measurement for their published specs, so often it’s hard to compare one manufacture’s specs to another.

    They are somewhat related. Dynamic range is the difference between the softest and loudest sounds. Like Chu mentioned, CDs are a good example from a playback medium, but the reproduction components have to have a good enough S/N ratio to deliver the dynamic range of the source material.

    Along the same vein, DVDs exhibit a much greater dynamic range and CDs; FM radio typically exhibits limited dymanic range because everything is compressed so much.

    Regards,
    Wayne A. Pflughaupt
     
  7. Daryl_hawk

    Daryl_hawk Agent

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    So what could be considered a "ggod" one? I noticed the HK spec was (IHF-A)...can't remember if the denon was too....
     
  8. Chu Gai

    Chu Gai Lead Actor

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    I think its reasonable to say that both receivers are going to be capable of reproducing recorded music. As to whether your speakers, your room, the listening levels you listen to, are going to present a situation where either receiver may not have sufficient power is another matter entirely. Clipping, not enough current reserves to properly reproduce sustained low frequency, high energy events is another matter.

    Right now, you're focussing much too strongly on a particular leaf and you're losing sight of whether the forest is appealing or not. Broaden your outlook and step back.
     
  9. Ted Lee

    Ted Lee Lead Actor

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    i've been trying to preach that forever. amen brother!
     
  10. Daryl_hawk

    Daryl_hawk Agent

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    cool, thanks for the input! Much appreciated. I know I am probably being a little too picky or over analyzing the specs but it is just that I want to ensure that I am going to be very happy this time if I upgrade.
     

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