Distortion only at certain frequencies

Discussion in 'Speakers' started by Rick Westfall, May 31, 2005.

  1. Rick Westfall

    Rick Westfall Stunt Coordinator

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    This is going to sound bizarre and I'm just guessing that it needs to go in this forum.

    A few months ago, I noticed a slight distortion (that is how I would describe it) coming from the center speaker. It only occurred while watching movies at an increased volume. It also only occurred at certain times. When it happened, I could rewind and reproduce the distortion at the exact same point in the movie so it must be caused be certain frequencies. So...being the genius I am...I assumed I had damaged my center channel. I took it out of the system and replaced it with another speaker. Again, being a genius, I didn't test it to see if it would do the same thing. We just got back to watching more movies and I noticed that the exact same thing is happening again. Tonight, while watching the second Austin Powers, I was able to pinpoint certain parts of the movie that caused the slight distortion (maybe buzzing is a better description). If you have the movie I can tell you exactly what part of it was obvious. First chapter while Austin is still in the bed and he realizes something is up. He comments he wants to watch a movie and exaggerates the word movie. That exaggerated word causes the buzzing. There are other parts in the movie, but that is the easiest one to describe.

    So...two speakers...same issue. Is it possible that a receiver would cause this or is it more simple like a wire that has gone bad (do wires go bad?). And why is it only occurring at certain frequencies????

    Quite a conundrum
     
  2. Steve_D

    Steve_D Second Unit

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    I've noticed alot of movies have certain points where the dialogue is distorted or harsh for a brief moment. It is reproducible in the same spot through different amps, processesors, and speakers.

    Thus, I can only deduct that the recording was not perfect. Remember, Actors are not in audiophile sound recording studios, it is to be exepected that there would be imperfections in the recording.
     
  3. John Garcia

    John Garcia Executive Producer

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    If you can repeat it consistently, at any volume, on multiple speakers, it is the movie.
     
  4. Wayne A. Pflughaupt

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    What John said. However, if it’s happening with other movies, it’s possible that playing at high levels you’re clipping the amp. It would be easier to help if we knew what receiver and speakers you’re using, and how large your room is.

    Regards,
    Wayne A. Pflughaupt
     
  5. Rick Westfall

    Rick Westfall Stunt Coordinator

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    Weird "distorted" sound is only evident at higher volumes.

    Receiver: Harman Kardon AVR-330
    Speaker: PSB Century Series 200Ci
    Room size: about 18'x18'x10'

    Thanks for all the help so far.

    Rick
     
  6. John Garcia

    John Garcia Executive Producer

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    I will try that scene out when I get home and let you know if I hear the same thing.
     
  7. PeterK

    PeterK Supporting Actor

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    On a related note, I notice a very high pitched, whine, I guess you'd call it when watching certain movies. Specifically during ROTK when that little hobbit guy is singing to that temp. king guy. (you know, the one that goes crazy in the end) well, as soon as that hobbit starts singing I can hear a very high pitched noise, and it really takes away from the movie. Anyone else notice this during that specific scene? [​IMG]
     
  8. John Garcia

    John Garcia Executive Producer

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    OK, checked the movie; no crackling at all in the specified portion of the movie, all the way up until the robot explodes. Maybe you have a bad amp channel? Did you check the wires at the receiver for that channel?

    I've never noticed any whine at all during the singing sequence, in either the regular or EE versions.
     
  9. alan halvorson

    alan halvorson Cinematographer

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    Every few months I start believing my system is distorting. My conclusion is always that something is wrong with my speakers, namely the upper midrange drivers, and I follow the normal steps to convince myself that I'm right. But I'm always wrong - the actual explanation is that my ears, particularly my right ear, are clogged with ear wax. Once they're cleaned out (I cannot believe how much wax my ears can contain!), no more distortion and I'm good for many more months.

    Kind of crude, but it's something to consider.
     
  10. Sean Buehrle

    Sean Buehrle Auditioning

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    i have the h/k avr 630 and it has the channel frequency set feature, does yours have that? if so try setting the center channel to the right frequency. maybe you are just getting signals that the speaker wasnt built to be recieving.
     

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