Help me decipher this...(long)

Discussion in 'Archived Threads 2001-2004' started by Mat_M, Mar 20, 2003.

  1. Mat_M

    Mat_M Stunt Coordinator

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    I have an issue with my Cinenova and was wondering if any of you could tell me what I'm saying is wrong here...These are the emails we sent back and forth:

    Got another quick question for you: Today I was watching Lord of the Rings on DVD. My pre/pro is a Harman Kardon AVR300. I had the volume at -20dB (max is +5), and there were a few scenes where the Cinenova's left front FFI LED indicator would flash on and flash off, and the channel would cut out for a few seconds. These were scenes where there was heavy bass. Is this a sign that the channel is or will be faulty? or what's going on? I'm no where near the maximum volume output, and the LED is flashing. What's this mean?

    Earthquake Customer,
    Mat M
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    I think that will pull current and make heat and no sound beyond its capability. Don't overdrive the speaker it is not good.
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    Ok, but here's a good question: The speakers are 8 Ohm speakers. If the amp could handle down to 2 Ohm speakers, why would the problem be too much current draw? Having 8 Ohm loads at the end would reduce the current draw as compared to 2 Ohms. On top of that, it's only the left front channel (as labeled on the amplifier) that is flashing. Now that I think about it, I truthfully think that I'm not overdriving the speakers because my volume level is still only at -20dB, where the maximum possible volume level is +5dB on the pre/pro. Speaking in terms of Watts, this still allows for an increase of 128-fold or so, since there is a difference of 20-25dB left of headroom. What do you think is technically going on? I'd like to know if this has happened in the past and what can be done. The whole reason I got the Cinenova was that I like watching my movies at loud levels, and I don't want to have the worry in my mind that something could fry.

    Thanks,
    Mat
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    Speaker impedance is never what you measure in DC It is always reactive hence the current is low. For example when you have signal close to system resonance, an 8 ohm speaker will actually be about 30 ohms. and a four ohm about 20 ohns to 15 ohms. Therefor when a voice coil leaves the gap it will measure DC impedance 8 ohm is lower than 15
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    That's exactly my point. If the speaker has higher impedance, the current will be lower. If the current is lower, then how can the unit be drawing too much current? I get the feeling that you're avoiding my questions. If you are unable to answer the technical questions, please hand them off to someone who can answer them. I do not want to get into an argument here, I just want my questions answered...please
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    man call me tomorrow at the factory I don't know what is going on but you sure got it wrong
    Joseph
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    So that's it...For those that aren't asleep from this post, what do you think is going on?
     
  2. GregLee

    GregLee Stunt Coordinator

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    The Earthquake guy is saying that he suspects your 8 ohm speakers have a very low impedence for some part of the frequency range, hence are drawing too much current for the amp to handle. At least, that's my interpretation. He chose to illustrate his point that 8 ohm speakers may have an impedance *different* from 8 ohms at some frequencies by (somewhat confusingly) mentioning an instance where the impedance is *greater* than 8 ohms.
     

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