Crackle sounds when the volume is loud..

Discussion in 'Archived Threads 2001-2004' started by Tim Kline, Feb 6, 2002.

  1. Tim Kline

    Tim Kline Stunt Coordinator

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    I posted about this before a while ago.. people that replied said it's because of the DVD I was watching, where they did a bad job with the audio. Basically, I'll be watching something and when there's a loud/high pitched sound (usually a scream or yell) I hear a faint crackling sound coming from the center speaker (where most of the sound is coming from anyway) .. it seems to me that it sounds like the speakers can't handle what's coming out.. but I really don't know much about this stuff..
    Anyway, it used to do it occasionally and always with the same DVDs at the same parts, but after recently tweaking some speaker volume settings in my receiver, I've been noticing it a LOT more now, almost any DVD has this problem now. My speakers don't make that buzz type sound like when they've been blown out, it's nothing like that.. it's just like some kind of staticy sound mixed in when there's something really loud. I've tried retweaking the volume settings and I just can't get rid of it at all now.
    As far as I know, for what I have and the money I spent, my speakers and receiver are really good. I did a lot of research before I bought it all and I got what sounded best to me. I have a monster cable optical cable going from the dvd to the receiver, and monster xp speaker cable all around, with monster banana clip thingies pluged into the receiver and speakers to connect the wires to. The only thing in my system that might be "cheapy" is my dvd player, it was Sony's cheapest model from about a year and a half ago. Could it just be that the player can't reproduce the sound good enough? I really have no clue why this keeps happening, but it's getting really annoying [​IMG] Anyone know how I can fix this or what I can do?
     
  2. Vince Maskeeper

    Vince Maskeeper Producer

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    Are you only getting it at high volume or any volume? What you're hearing is distortion because signal is clipping. This could be happening at one of several stages:

    1) It was recorded clipping: as others suggested- some DVDs do have edgy clipping sound on loud dialog passages.

    2) It's clipping in the decoder stage- cheap D/A decoders will run out of headroom and crap out on certain signal. Not common for DVD- usually more common on CD conversion.

    3) It's clipping in the preamp stage: This would be my guess, that you are boosting your center channel in the speaker setup, and the preamp is running out of headroom. I have seen receievrs that start introducing distortion as soon as you boost the center over +2

    4) It's clipping at the amp stage: The level of the Center coupled with the volume is feeding too much signal into the Center amp. This would probably be heard only when the volume was up high- and wouldn't be heard if you reduce the volume.

    5) It's clipping the speaker: the level into the speaker is maxing the driver and it is distorting. Also possible.

    The best ways to test these would be to try reducing the volume overall, and then trying reducing the Center channel level- and combinations of the two (CC level all the way up with low volume, and then CC all the way down with high master volume). Figure out when it happens, and you should be able to narrow it down a bit.

    -Vince
     
  3. Tim Kline

    Tim Kline Stunt Coordinator

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    it seems to only happen when I have the volume loud (past -40db, I used to listen at -35 for DD movies and -40 for DTS), and only with DVDs (that I've noticed anyway, TV and CDs seem fine)

    I have the rear speakers both set at +5.. could it be that they are taking too much power that should go to the rest of the speakers? right now my center is set at 0, subwoofer is set at -5 (I have the volume on the SW cranked to the top and I'm controlling it with the receiver)

    I've tried using DSP settings on the receiver (like sci fi, adventure, etc) and that doesn't help
     
  4. Vince Maskeeper

    Vince Maskeeper Producer

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    Tim,

    Probably not the result of other speakers being too high- it sound like you're just running out of headroom somewhere in the chain to the center.

    Did you try swapping another speaker in its place and see if you hear the same thing? That's what I would try first, to see if it stays/goes.

    If it goes, it's the speaker. If it stays, I would try routing teh CC stuff to the left or right speaker- using the cable for the left/reight speaker (in other words switch the cables at the receiver- so you can see if it might be the Center channel cable that is a problem).

    -V
     
  5. Adam Barratt

    Adam Barratt Cinematographer

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    Unfortunately, even if the crackle is traced to a hardware problem you'll still have to suffer through some occasional distortion from the centre channel on many DVDs. This is actually present on the DVD, as Vince mentioned, so cannot be avoided.

    Can you cite any particular titles and chapters/times when this crackling is occurring (The Fifth Element, for example, is notorious for its high level of distortion)?

    Adam
     
  6. Sean Conklin

    Sean Conklin Screenwriter

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  7. Tim Kline

    Tim Kline Stunt Coordinator

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    Yes, I have the 5th element Superbit, that's a bad one on both DD and DTS.. I have the Jurassic Park DTS (original one not the one they redid) and the trex roars and people's screams are real crackley.. the terminator, same thing with any time someone screams or yells.. I was even watching some south park DVDs and noticed at almost every "Oh my god, they killed kenny!" part.. there's a lot of dvds that I have where I hear this though, they're just a few that come to mind offhand.. now that I think about it.. I just watched Meet Joe Black (ultimate edition) 2 nights ago for the first time, and didn't hear any crackle.. I'm guessing now that maybe after I finally figured out how to tweak my system, it's pointing out more flaws in the DVDs than I might have heard before? Why can't one of these companies make a special reciever with crackle-elimitator technology [​IMG]
     
  8. Vince Maskeeper

    Vince Maskeeper Producer

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    Again- I would check everything before I gave up on it. If it is extensive- it could either be you being critical- or could certainly be an issue of gear exaggerating it.

    I would start at low volumes and get close to the speaker, ear against it, and see if you hear the crackle. Try swapping speakers around- or sending the CC signal down different speaker cables.

    Just play around a little- you'd be suprised- much modern equipment is flawed in the conversion or playback stages.

    -V
     

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