Should my pb12/2 ultra be doing this with Empire Strikes Back?......

Discussion in 'Speakers' started by Todd smith, Jan 1, 2005.

  1. Todd smith

    Todd smith Supporting Actor

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    On loud bass heavy moments the sub will blurt out a distortion type sound. At this moment it is also verry obvious that the bass is coming from the sub. I noticed this a few times before with other discs but it is verry rare and was not cause for concern, but I dont think it is the movie for some reason. I borrowed another copy from a friend thinking the disk might be bad, but got the same results. Is this normal with Empire Strikes Back or do I have some sort of other issue? Should I be able to locate the sub in this movie? This happens on every bass heavy pasage in this movie and it sounds like crap. A couple examples are when the doors close in chapter 5 I beleive when leia is talking to R2 and c3po. Another example is when Luke crashes his ship in the marsh.

    I have the phase optimized for blend with my mains and am pretty flat down to about 40hz with the sub about 3db hot. The sub is in the rear corner behind my couch in a 12x17 fully enclosed room. I dont think it should be calling attention to itself like this. Any ideas on what the problem could be, or is this just how the movie is?
     
  2. Des Flurane

    Des Flurane Auditioning

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    Hi Todd,
    You need to give more info, ie what level/spl are you listening at and what tune the SVS is in.
    Des.
     
  3. Benihana

    Benihana Stunt Coordinator

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    maybe its easier to localize because its behind you like in a car environment? How far away from you is the sub?
     
  4. Jon_Liu

    Jon_Liu Stunt Coordinator

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    one possibility is that it is port noise. That's the easiest possible idea that I can think of. If you are running your sub in a lower tune than at stock, then chances are more likely. We need to know what volume you are listening at.

    Test those same scenes and check to see whether or not you can hear an "audible" chuffing-type noise from one or more of the ports.

    Let us know more on what you find!
     
  5. Todd smith

    Todd smith Supporting Actor

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    Have not had a chance to check for port noise, but when I do I will get back with you all.

    The sub is running about 3 db hot according to Avia and I am listening to this disk at -10 below ref. I am running in the 20hz tune with one port blocked. It is loud but I have played movies louder with no sign of this. Just got done watching matrix revolutions and it sounded awesome as do most other disks so I am wondering If it is just the way this soundtrack was mixed. episode IV, A New Hope sounded great and did not do this which is why I am kind of stumped. I have not tried episode VI yet.
     
  6. Kevin C Brown

    Kevin C Brown Producer

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    One definite is that your sub is set too loud (personal preferences aside). With Avia, you should actually set the sub level at 2-3 dB lower than what Avia says because the Radio Shack SPL meter is less sensitive at lower freqs.

    I.e., if you set the sub at 0 dB level (to 75dB), you are already accidentally compensating 2 to 3 dB for the lower sensitivity of the RS meter at those freqs.

    But to be honest, running ~5 dB hot shouldn't be a problem for this sub.

    If it's port noise, how far is the sub from the wall? SVS told me 4 inches was enough to elimate the worst of it.

    (I have a PB12-Ultra/2, and I've never noticed any kind of distortion in 4 odd months with it. The Empire Strikes Back too. [​IMG] )

    I suppose there is the odd chance you have a defective unit.

    What crossover freq are you using? (I.e., if it's substantially higher than 80 Hz, that itself might be the problem.)
     
  7. Peter Fallon

    Peter Fallon Extra

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    Having the sub behind your listening position could be part of the issue. Subwoofers usually become easier to locate when you move them away from the main speakers, and having it behind the listening position is about the worst case scenario in this regard.

    For the sub itself, double check the Subsonic Filter and make sure it matches your tuning.

    You also didn't mention if this specific problem went away at lower volumes.
     
  8. Edward J M

    Edward J M Cinematographer

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    Make sure nothing nearby the sub is rattling.

    Make sure the sub feet (small hard rubber discs) aren't vibrating on a hard smooth floor. If they are, try the optional 3M rubber bumper feet for better grip and vibration isolation.

    Try the 25 Hz tune temporarily and see if the noise goes away.
     
  9. Craig Chase

    Craig Chase Gear Guru

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    Just because no sacrifice is too great, my son and I are going to watch "Empire" this morning. We have twin Maestros in a 25x24x9.5 foot room ... and will let you know if there is a problem.

    Oh ... and the sacrifice part was humor ... [​IMG]
     
  10. Craig Chase

    Craig Chase Gear Guru

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    We have "The Empire Strikes Back" on now ... and are through the part where the Rebels escape from Hoth.

    The dialogue is running between 70-75 dB ... and for fun, I am running the subwoofers 6 dB "Hot" ... We are seeing 107 dB peaks on scenes like the Blast doors in the Cave closing, where the Star destroyers are in orbit, when the AT-AT's are both walking, or being destroyed ...

    Almost EVERY bass peak is hitting at the 107 dB point ... though some are less.

    My TrueRTA is kaput, at least until I get my laptop back. These are all uncorrected values with a Rad Shack.

    And the bass seems to be mostly 25-35 Hz stuff, but I cannot measure that part right now, it just does not feel like infrasonic stuff...

    I think the guys are right ... try the 25 Hz setting ... We are not getting any audible noises here ... just room shaking bass, and a PB12-Ultra/2 should have NO trouble in a 17 x 12 foot room ...

    EDIT ... I typed this in a dark room... can you say TYPO ?

    Also ... It is clear the bass spectaculars are "add ons" for the DVD release ... I wish we had TrueRTA to have run sweeps ... on a few scenes, we were getting some SERIOUS floor shaking... suggesting some infrasonic material.
     
  11. Mark Seaton

    Mark Seaton Supporting Actor

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    Hi Todd,

    The first question to answer is if the sound goes away when you set the volume lower. If it is only at a higher level, then as Ed suggested, confirm the sound is from the sub and not from something the subwoofer is causing to rattle. Moving the subwoofer somewhat and/or unplugging your main speakers during the scene can make this easier to identify.
     
  12. Todd smith

    Todd smith Supporting Actor

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    Wow! Thanks for all the replys. I appreciate the sacrifice Craig! I know it is tuff to have to watch these terrible movies again!

    Double checked the subsonic filter and it is set right.

    Just tried the 25hz setting with no port block and got same results.

    Tried the lower volume setting of -30 below ref and got same results.

    I even got anoter copy of the movie thinking I might have a bad disk, but the new copy does the same thing.

    This sub is on carpet so it is not rattling, and the sound is definately coming out of the drivers. I put my ear down there during the scenes and it is coming from the drivers.

    I am using an 80hz cross by the way as well.

    The sub is about 6 inches out from the sidewall, and about 8inches out from the backwall so I should be far enough out from the wall.

    Unfortunately I cant put the sub up front because my FR charts are Horrible with it up there. This is the best spot for it which unfortunately is behind me.

    It is verry localized when the higher bass freq type stuff like spaceship engine noise plays on it. The woooooshh type sounding stuff. The deep stuff you cant localize, just the higher bass freq. Something is telling me this is not right though. It just sounds bad. I had the GF come in and listen to see If maybe I was crazy (which is always possible!) but she heard the same thing and agreed it sounded off.

    What do you guys think? You guys cant localize the sub at all in this movie during the action scenes? Specificaly the scene in space when the mil falc goes into the asteroid belt and right before that when they are trying to get away from the other ships?
     
  13. Craig Chase

    Craig Chase Gear Guru

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    Todd... I just replayed that scene ... everything here was good ... I am not sure what is going on with your subwoofer. Bummer.

    Edit/Addition ... If this is the only problem you are having, it is likely nothing to worry about...
     
  14. Todd smith

    Todd smith Supporting Actor

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    Thanks Craig for your help. If no other movies or discs present a problem I am not going to worry about it. It is a bummer though as I love this movie and it sounds better with the sub off. Thanks again.
     
  15. Tom Vodhanel

    Tom Vodhanel Cinematographer

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  16. Benihana

    Benihana Stunt Coordinator

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    yeah, most likely it is the subwoofer thats crapping out. this is where "great customer service/support" kicks in [​IMG] . GO TOM!!!
     
  17. Todd smith

    Todd smith Supporting Actor

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    Hi Tom,

    SVS has been exceptional to me already as far as the customer service goes with a few other issues I had initialy. I will email you guys so we can talk further and see if we can figure out what is going on. I have issues with email on my home PC so it might be tom or next day when I can email you from work.

    This company deserves all the praise it gets on this board and every other board I have been on. I truly feel safe with my purchase from these guys which unfortunately is somewhat rare in todays world. Whenever I recomend an SVS to someone who comes to my house part of the reason is because of this type of service. You dont get the all sales final attitude with these people. Awesome company.
     

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