Help with noise coming from SVS grill...Please!!

Discussion in 'Speakers' started by Vader, Apr 24, 2006.

  1. Vader

    Vader Supporting Actor

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    Derek
    OK,

    All of you other SVS owners out there, I have a puzzle for you. I have had my SVS 16-46 PCi sub for about a month now, and am continually blown away by it (sometimes literally). The other night, I was watching “The Exorcism of Emily Rose”, during which a loud rattling sound came from the direction of the sub. I traced the sound to the grill, by removing it and repeating a specific sequence (no rattle w/out grill). Jim and Eric at SVS were fantastic at trying to help me troubleshoot this, going far beyond the call of duty, but here’s the rub: while the sound was clearly related to the grill, nothing we did to try and dampen the sound worked. After adding more foam blocks, replacing the grill itself, and adding foam shims (the grill is now extremely tight (no chance in hell of vibration), the sound is just as loud. Quite by accident, I discovered that the sound is caused by air turbulence (and not vibration), as the air blasts pass through the grill (I put my hand above the grill-less port to the same effect), so now I simply remove the grill when watching a movie – and the bass is absolutely perfect to my ears. Thing is, I don’t listen to my movies at anywhere near reference levels, and I know I’m only pushing the SVS to a fraction of what it can do. Many here push their subs much louder, and are just as discerning (many more so) as I am. And yet there is not even one mention of this… Anybody have any thoughts on this, or am I simply succumbing to premature senility here? HELP!!!!
     
  2. ShaunVanSkiver

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    I had a problem with my pb12. come to find out it was the seal on the bottom of the driver. the one that seals up against the box. when it was assembled it was not seated right and was allowing air to push by making a strange buzzing,clapping sound. just a thought
     
  3. Vader

    Vader Supporting Actor

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    Shaun,

    Thanks for the reply. I had thought at the beginning that it had something to do with the driver, but eliminated that possibility when I removed the grill and the rattling stopped. The sub makes the "rattling" sound only when anything impedes the air blasts coming from the port. I'm no engineer, but I think it is akin to wind travelling through trees...? Removing the grill solves the problem, and I have no problem doing that. I'm just confused that I'm (seemingly) the only person that has noticed this. Maybe it's the environment the sub is in that amplifies this sound (really dragging the bottom of the barrel for an explanation).... It's driving me crazy, though...[​IMG]
     
  4. ShaunVanSkiver

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    well my sub is down firing so it has a base plate about 2 inches from the sub. when i took the plate off the sound was not as noticeable if at all. i think with your screen on, it may be just enough pressure to push air through a seal. I dont know how easy it is for you to check the seal but it's just a thought. It wasnt until i played the test tone cd from realtraps.com that i was able to pin point the problem. good luck, shaun
     
  5. ShaunVanSkiver

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    heres what it looked like
    [​IMG][/url][/url][/IMG]
     
  6. TimJC

    TimJC Stunt Coordinator

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    The "air through the trees" analogy is a good one in this case.

    The sub is nearing max excursion at or near the tuning point when this happens, and the velocity of the air moving through the small holes in the grill screen is causing a whistling sound. I've heard it before on my PC Ultra when testing (but WAY louder than I would normally listen to). Take it as a warning signal that you're likely very near bottoming the sub when this happens.


    Tim
    [​IMG]
     
  7. Vader

    Vader Supporting Actor

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    Shaun, thanks for the picture. I will check when I get home tonight.

    Tim, that's what I don't understand. From everything I have read, the 16-46 PCi should be able to do a lot more than what I am asking of it without breaking a sweat. The volumes I listen at don't exactly "crack the foundation", either. For example, the plane crash sequence in "War of the Worlds" (2005) peaks at 95 dB (determined via a Rat Shack SPL meter). I know that the PCi is entry level, but every review I can find suggests I am just skimming the surface. I will check the specific sequence where I hear the "rattling" tonight (almost nothing but bass)...
     
  8. SVS-Ron

    SVS-Ron Screenwriter

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    Tim,

    Exactly. Despite the port on these subs, the air pressure inside is quite intense at times.

    Any flawed seal (in this case with the other's we've seen and fixed ... this one notwithstanding) will allow an air breach. Amp leaks are as bad or worse because they are so hard to find (we double seal all amps).

    Just in case we're sending you another gasket today.

    Ron
    SVS
     
  9. Vader

    Vader Supporting Actor

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    OK, now I am worried. Ron, how hard should I be able to push the 16-46 PCi before bottoming out? The room my theater is in is approx. 2912 cu. ft. (1792 for the theater with the back 10' open with bookshelves), my sound is calibrated to 5 dB below reference, and I typically listen to movies at 13-16 dB below reference...
     
  10. SVS-Ron

    SVS-Ron Screenwriter

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    Derek,

    A 16-46PCi (which is tuned ultra low but isn't the most powerful sub for most music and HT use because of that) in a 3,000ft3 room?

    That's actually pretty predictable if pushed hard enough, and if the sub is calibrated even the slightest bit hot, approaching the levels you might be could explain a lot. Depending on your seated distance from the sub and what you used to calibrate and the program material (WOTW has some simply insane deep, and powerful stuff) ... it's certainly possible to bottom a PCi with that much space to fill (don't forget your sub will "see" all that air space).

    A dual PCi or at least a Plus sub should be the goal. Or even shifting to a less deep but ultimately more powerful 20-39PCi would be worth considering. Now, having said all that, it's still possible there is an issue but some momentary air noise thru the grill could happen too. Is the sub on a hard surface or carpet BTW?

    Would a second PCi or a single or dual Plus be within reach?

    If there's problem it'll be fixed. If it's a situation where your taste dictates more subwoofer than you have now (which is not clear but certainly possible given some unknowns still) then it's nothing that can't be "fixed" but adding more capacity than you got.

    Filling a 3,000 room with a $650 sub, even if it's the best $650 sub in the world, isn't matching with the reality of today's Hollywood blockbusters like WOTW with the tools you have (again good as it is, that PCi has some limits a 3,000 foot can expose, something we or anyone with a a grasp of the physics involved will be honest about). There are many ways to optimize what you have though, including simply swapping out what you have with something else that might address the space issue with some different aspects to performance addressed (such as mentioned above, a slightly less deep solution that'll have more headroom in the more active 25hz and up region).

    Drop me a line and we can work it a bit more while I'm still at the factory.

    Ron
    SVS
     
  11. Vader

    Vader Supporting Actor

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    Ron, YGM.
     
  12. Vader

    Vader Supporting Actor

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    Ron, my email is currently down, so I sent you a PM as well...
     
  13. Vader

    Vader Supporting Actor

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    Ron,

    Here are the results of last night’s tests.

    1) I looped the sequence from "The Exorcism of Emily Rose" that first showed the "rattling". It is a dream sequence that has some very low, powerful bass (and only bass). I then measured the SPL at both my listening position (10') and right next to the SVS (3'). This yielded SPL readings of 88 dB and 94 dB, respectively (This was at 15 dB below reference). The only additional sound other than the bass was a slight low whistle as the air escaped through the port. When I replaced the grill, the intensity of the rattling sound was directly proportional to the amp volume (as would be expected), but was still present at lower volumes as well.

    2) The pod race sequence in "The Phantom Menace". This one was at 12 dB below reference (the audio seems to be coded lower than normal), and it sounded great. The air blasts were more of a constant breeze for this one, even though the bass was much stronger (but not as low). For most of the sequence, the grill did not cause the rattling sound (only a second or two).

    3) The opening of "Attack of the Clones": the flyover and approach of Amidala's ship, and the explosion after the landing. Again, very strong, smooth, tight bass with little "rattling" from the grill.

    In all, the sub handled each test flawlessly (w/out the grill) at the volumes I listen to. The problem (if it is a problem) comes with extremely low bass, which results in more of a “puff, puff” air flow out of the port, as opposed to a constant breeze (can I equate each “puff” to an “up-down” movement of the driver?) My only concern is that, as Tim pointed out, I could be dangerously close to bottoming out the sub (what is the difference between bottoming out and blowing the driver?). If I were to upgrade to a 25-31 PC+, would that yield more headroom?
     
  14. RichardH

    RichardH Supporting Actor

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    "If I were to upgrade to a 25-31 PC+, would that yield more headroom?"

    I'm not Ron, but yes, absolutely. Not only are you stepping up in terms of driver and amp power, but you're going from the low (16Hz) tune to the high (25Hz) tune. You will definitely gain some headroom by doing that. But you will be giving up the low bass, so you might not want to do that. You might consider the middle PC-Plus, the 20Hz tuned one. You can pop in 1 port plug and go to 16Hz on that, so you can get the depth back. If you're at the same volume levels, you should be able to manage that given the new Plus driver, but I'm sure Ron/Tom will give you the scoop on that.

    Alternatively, you could try a shorter port in your sub, like maybe 20 Hz, but I don't know if you could just swap out without changing something on the amp. The PCi amps don't have the selectable subsonic filter because they are not variable tune capable w/ port plugs.

    HOpe all this makes sense, and hope you get your problem fixed!
     
  15. Vader

    Vader Supporting Actor

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    Richard, I was thinking along those lines as well. The 25-31 PC+ can also tune down to 16 Hz w/ 2 port plugs, but I'm thinking more along the lines of 20 Hz w/ 1 port plug (since in-room extension will take me close to 16 Hz anyway). I checked the order date of the 16-46, and two months have passed (I'm past the 45 day limit). I'm hoping the guys at SVS will have pity on a poor, dumb sod like me...
     
  16. ShaunVanSkiver

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    derek, here's a quick refrence if you want it. when watching the incredibles "Ouch", Scene 15 (0:58:15)* i get a reading in my main listening position at -18 below ref. of 98-100db i have the sbs-01 with a pb12-nsd [​IMG] with pioneer vsx-742txv. room is a 20x13x8 and opens up at one end. and a walk way into the kitchen at the other end.
     
  17. SVS-Ron

    SVS-Ron Screenwriter

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    Derek,

    What Rich said. But don't get the sub you have to stop down at all, you need all headroom (and maintain max efficiency) you can get. In this case I'd say simply get the 20-39PC+ and leave it in the all port open 20hz mode.

    That or get a second 16-46PCi.

    Done.

    Or rather at least you are in a good place that'll hold you till you go gonzo and get the dual PB12-Plus/2 subs I know you are secretly lusting for (and frankly should have in a perfect world where we're all thin, rich and good looking).

    PS Give a call or e-mail us immediately and we'll probably be able to more than meet you half way on this much needed upgrade for your Biggie Sized (TM) room.

    Ron
    SVS
     
  18. Vader

    Vader Supporting Actor

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  19. Vader

    Vader Supporting Actor

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    I just placed my order for a 20-39 PC+!!!!! Even though the 16-46 PCi is performing very well, after all that you guys have told me I would never be able to not worry after every bass-heavy passage: "Did that push it too far?". Thank you all (esp. Ron, Erik, Jim & everyone at SVS), and I will divide the bill to fix my cracked foundation (not to mention my dog's therapy) between you.....[​IMG]
     
  20. Vader

    Vader Supporting Actor

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    I just got the 20-39 PC+, and recalibrated it to the same SPL as the 16-46 PCi. I didn't know my jaw could literally hit the floor (I always thought that was a figure of speach). The bass was even more authoritative, and as far as headroom gained? The speaker settings on the AVR were FL: +1.0; CTR +1.0; FR +1.5; RS +2.5; BRS -6.0; BLS -6.5; and the sub (16-46) was at +3.0. With the same calibration, the 20-39 is now at -6.0!!! And last night, my wife was upstairs, and had a window cracked. Our neighbors were outside having a BBQ, and she asked "Daddy, what is that really low 'thump, thump', and where is it coming from? Next door, honey. They must have a subwoofer." I guess the slogan "Get to know your neighbors" is more than just a slogan....[​IMG]
     

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