Buzzing Sound

Discussion in 'AV Receivers' started by RobertJohn, Jun 20, 2005.

  1. RobertJohn

    RobertJohn Auditioning

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    Over the weekend, we rented "The Incredibles". During some of the passages, perhaps when there would be an explosion, There would be an annoying buzzing or rattling sound from one or both of the main speakers. The receiver is an Onkyo TX-SV727 capable of 80 W per channel, and the speakers are old inefficient McIntosh ML-2M. I don't notice this sound during normal listening. What is your best guess as to the cause, and how could I check to be sure ? Thanks. Bob
     
  2. Jesse Sharrow

    Jesse Sharrow Supporting Actor

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    "old inefficient" + "80 W per channel" = Maybe a blown speaker? [​IMG] [​IMG]
     
  3. John Garcia

    John Garcia Executive Producer

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    There's nothing wrong with inefficient speakers, as long as you have enough real power to drive them. They seem like they should be pretty decent speakers based on what I could find, but I couldn't find specs for them.

    Did you notice if it is during scenes with deep bass/loud sections in particular? The Incredibles has a LOT of very low frequency bass, and if you are running these speakers full range, the sound present in the movie is likely below what these speakers are capable of reproducing, so you get some "buzz" instead. Music and TV contains little or no deep bass, so "normal" listening would be unlikely to have very low content like some movies do.
     
  4. Jack Briggs

    Jack Briggs Executive Producer

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    Regarding "normal listening": Just how loud did you have your equipment when you noticed the buzzing sound?
     
  5. RobertJohn

    RobertJohn Auditioning

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    Gentlemen, thanks for the replies.
    Jack: We were listening at a comfortable listening level. I will occasionally listen to music very loud, and my tastes run from rock to classic. The speakers seem to have had no damage. But when listening to movies with dialog, I listen at "reasonable" levels. I might add that these old McIntosh speakers were designed as overdamped and must be used with an equalizer, and I normally run the lowest two frequencies on a ten frequency equalizer with about an 8 to 10 db boost. On all normal music ( other than a few newer movies ) the speakers do fine.
    John, the scenes which caused the problem seemed to be ones in which there would be a considerable increase in volume over the normal level, such as an explosion. I don't have a subwoofer because these speakers each have two large 10 or 12 inch woofers, and until now have been satisfactory.
    I do appreciate your expert advice helping to figure this out.
    Bob
     
  6. John Garcia

    John Garcia Executive Producer

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    I'd have to say a sub will likely help your situation considerably, in two ways: 1) your receiver will work a little less by letting the sub's amp handle the low frequencies and 2) your mains will not have to try to reproduce frequencies below their range. It sounds like these two conditions are probably combined, at least in some part, to create your issue. The boost may be a factor too, so maybe for movies, you might want to drop it down a bit.

    Just because the mains have large drivers does not mean they can handle the really LOW information (low 20s and below) that is becoming much more common in movie soundtracks. This is even below the range of many mass market subs... Incredibles has quite a few scenes where the bass drops down into the teens, and at least one scene that is as low as 5Hz (see the waterfall thread)! My sub was getting a nice workout with that movie [​IMG]

    Give this thread a look too. His second post.
     
  7. RobertJohn

    RobertJohn Auditioning

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    John, I hope this isn't too stupid a question, but if I connect an amplified subwoofer to the subwoofer pre-out terminals of my Onkyo recvr, how will the McIntosh spkrs on the main channels know it's there and what is to prevent them from continuing to buzz/rattle ? I understand how a dedicated amplified sub would do a better job of taking care of those very low frequencies, what is to keep the existing speakers from unsuccessfully trying to do it also ?
     
  8. John Garcia

    John Garcia Executive Producer

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    In your receiver's speaker settings, there should be a setting for the speakers to be set to small or large. Large = full range, small = use receiver's crossover to distribute the low information to the sub and the information above that point (blended together, centered around the crossover point) to the other speakers. I am not familiar with your exact model, but since you indicate that it has a sub pre-out, I am going to guess that this setting will be present. You may also have to set subwoofer = yes.
     

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