i finally heard the dreaded clack...

Discussion in 'Speakers' started by David_Stein, Aug 17, 2003.

  1. David_Stein

    David_Stein Second Unit

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    of my svs bottoming out. before i had an underpowered amp and its own clipping protection circuitry would engage well before any bottoming out would occur.

    but now im running with plenty of power and it was bound to happen. i was demoing the 'return to coruscant' scene from attack of the clones and while trying to find the loudest i could play i ended up bottoming it out on 3 different occasions. twice when finding the highest i could listen to the actual explosion and then once i thought i had the right volume i played it from the beginning of the scene and when the ship flies by it did it again.

    now needless to say im a bit paranoid about doing it again. my baby seems to sound fine now, but i dont want to hurt her.
     
  2. MingL

    MingL Stunt Coordinator

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    I too bottomed out my SVS, but only if I was going really loud, or had not used the correct tuning/SS filter.

    Nonetheless, those few scenes there have got alot of bass action. You can view some waterfall plots of mine to see what type of bass the landing-to-explosion sequence has.
     
  3. Frank Carter

    Frank Carter Screenwriter

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    Which SVS are you using David?
     
  4. David_Stein

    David_Stein Second Unit

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    20-39CS+ with a crown CE1000 in bridged mono mode (1100w into 4ohms) in a room that is about 1500 cubic feet (12x15) and a lot of furniture. needless to say im quite happy with the bass output. even after turning it down i was getting uncorrected bass peaks of 112db (c-weighting, fast) through that ship fly-over.

    im just going to put the BFD on top of my list of things to buy. that way i can use one filter to get rid of the stuff below 18Hz or so as well as even out my response. im assuming that what bottomed it out. then i will be in true bass heaven.
     
  5. Brian Bunge

    Brian Bunge Producer

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    I think 1100W into that sub is a bit crazy. A single channel should be plenty of power. Also, IIRC, the BFD does not have a filter setting below 20Hz.
     
  6. David_Stein

    David_Stein Second Unit

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    you are right, it is, but i cant help but like the feeling of being able to say i have a sub powered by 1100w [​IMG]

    would putting it on one channel prevent it from bottoming out? if it would could you explain how because thats a bit knowledge i am lacking.

    and thats too bad about the BFD, i guess ill have to find something else, like a black box?
     
  7. DanielSmi

    DanielSmi Second Unit

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    No putting it on one ch wouldn't do that if anything it'd make it worse. The only thing that would help besides turning the volume down (i know you don't want to do that) is to get a subsonic filter to cut out the subsonic frequencies since you can't hear them and they work you sub the hardest and is probably what is making your sub bottom out. My Velo HGS-10 has 1200w and a subsonic filter at 20Hz to prevent this from happening.

    Daniel Smith
     
  8. David_Stein

    David_Stein Second Unit

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    i didnt think so. i really dont mind turning it down because im still getting excellent bass at what i believe to be safe levels, but i will be looking into a subsonic filter.
     
  9. Brian Bunge

    Brian Bunge Producer

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    Daniel,

    I don't understand your logic. How would less power make bottoming worse? Too little power will cause you to clip the amp and possibly damage the driver, but that's not the same thing as bottoming. And I'd hardly call 450W not enough for the driver.

    Also, the subsonic filter in your Velo is hardly the only reason it won't bottom out.

    David,

    So you're nixing a BFD because of a 2Hz difference? If anything, a filter at 20Hz will be even more beneficial since the sub is tuned to 20Hz. It'll cause it to roll off even faster and offer up even more protection from bottoming.
     
  10. Philip Hamm

    Philip Hamm Lead Actor

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    "the dreaded clack" ... Any relation to Parker Clack? [​IMG]
     
  11. David_Stein

    David_Stein Second Unit

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    Im not going to nix the BFD completely, as with my small room im pretty sure i have room modes to smooth out. i havent had a chance to do a freq. response measurement, partly because i dont want to know how bad it is until i have a BFD and partly because i havent had the time, but i have noticed that some frequencies seem a bit louder.

    but there is a part of me that also says in this small room i should be able to extend flat to below 20Hz and the same part of me that says "[​IMG] [​IMG] [​IMG] 1100w and an SVS CS+[​IMG] [​IMG] [​IMG] " also doesnt want to give up any extension i can get.

    thinking logically, i should probably just use a 20Hz subsonic filter and perhaps even just buy an FMOD to protect my sub until i can afford a BFD, but i am having a hard time rationalizing giving up some frequencies. im guessing im not the only person that has felt this way, but give me some time and ill realize that protecting what bass i do have is worth losing some really low bass.
     
  12. Brian Bunge

    Brian Bunge Producer

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    David,

    How small is "small"? What are your room's dimensions? And I'm not sure what frequencies you think you'll be giving up if you use a 20Hz filter vs. an 18Hz filter. I highly doubt the difference would be audible.

    I've got a 2500W amp and a Tumult, but I'm only using 800W as I really don't want to blow a $500 driver again.[​IMG]
     
  13. David_Stein

    David_Stein Second Unit

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    approximately 12'x15'x8'. im assuming its a small room, as i think
     
  14. Brian Bunge

    Brian Bunge Producer

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    That's pretty small and a single channel of the Crown should be plenty. The only real advantage of switching back to one channel is that it's a bit safer if you have a roommate or friend that likes to crank things when you're not around.
     
  15. DanielSmi

    DanielSmi Second Unit

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    Sorry Brian I was thinking he meant bridging the two channels into one.

    Daniel Smith
     
  16. Brian Bunge

    Brian Bunge Producer

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    Daniel,

    That's the problem. He already did that! [​IMG]
     
  17. Ron Stimpson

    Ron Stimpson Stunt Coordinator

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    David,

    As you noted, you could put "1.21 Jigawatts" behind your sub and not have a problem with it "bottoming" IF (big if here) you calibrate it properly with a sound meter and test disk (I simply do NOT trust any receiver tones to be very accurate), IF you situate it well in your room (corners work best in any methodical testing we've seen)... and... if your room doesn't double as an aircraft hangar.

    However, having at least double the power in your bridged amp as you need to bottom a CS-Plus sub is simply asking for trouble and using "only" one channel might limit things a bit (though clipping can also cause problems and you don't want to now push one channel to clipping).

    With one channel or bridged mode, if you want to run a Plus sub on the ragged edge (it should sound good right up to that point -- which of course is a double-edged sword) then I think you should:

    1.) Turn it down at least to the point that your most punishing movie doesn't bottom the sub even at the highest master playback level you are likely to ever use. The first 5 min. of Toy Story 2 is perfect for this test IMO.

    2.) Get a subsonic filter in the mix ASAP. The BFD has lots of fans, and if you don't use it to ALSO boost various frequencies it should work well to help curtail some of the deepest stuff that can cause bottoming. We sell a simple subsonic filter box made specifically for the CS-Plus and CS-Ultra subs that will work well too.

    3.) Take out the port plug. (If you are using one that is.) While helpful for squeezing out a few dBs in the lowest octaves, it also curtails useable headroom in more common bass ranges above 20Hz. You'll get the most average output with the least strain on the woofer using all three ports. Using a port plug without a subsonic filter is pretty much worst case scenario for any multiple tunining point passive sub rig.

    4.) Get a second CS-Plus and put it right next to the first. You'll get FAR more useable bass with far less bottoming (and ultimately durability issues) by running that amp in stereo and feeding one channel to a matching CS-Plus.

    Of course if you are OK with simply turning the LFE/bass mix down a bit then that's easy and cheapest of all. Anyone that can bottom a CS+ though should already consider running dual subs (and applying the other options above too!).

    The CS+ subs are pretty darn powerful and durable. Except for our CS-Ultra they're pretty much unmatched. At their price they ARE unmatched. But they have limits that 1,100 watts will discover without some moderation injected.

    Ron
     
  18. David_Stein

    David_Stein Second Unit

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    first off, thank you everyone for all the information. i really appreciate it.

    basically this whole thing was an exercise in the limits of my sub, because like everyone else i just want the most (safe) performance out of my sub and really until you know the limits until you try.

    basically the only reason that i have it in bridged mono mode is because it was there. i found when trying to find an amp that it was just easier to just buy a two channel amp with that much power. and then once its in your hands its hard to not just set it up that way.

    as much as i would love to get a second CS+ (theres even room for it in my room [​IMG]) monetary and more importantly moving constraints (i am in a dorm room so i have to move at the end of the year and who knows where i will be going) will keep me from doing that, so its not likely that the other channel will be used any time soon. but it is there for the future.

    a BFD is likely going to have to wait til mid october or maybe christmas. would just getting one of those inline FMODs (20Hz) from partsexpress be a good way to relieve my SVS in the time being?

    for the time being im just going to keep it turned down, but even that is a bit of a misnomer, even with it "turned down" to safe levels i am still getting reference or near reference levels of bass. ill also just switch it over to one channel next time i am working on my system.
     

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