Spikes on sub... will it help?

Discussion in 'Archived Threads 2001-2004' started by James Bergeron, Jul 16, 2002.

  1. James Bergeron

    James Bergeron Supporting Actor

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    I have a Velodyne CHT-15 and yesterday I calibrated to reference, set it to reference, cranked the pod race scene and went to my neighbours.

    It was cool, you could hear nothing from the movie, but MAN outside and in his home you could feel bass energy it was kind of creepy feeling. Just this VERY low rumble that was just felt (kind of like an earthquake).

    So he suggested I try spikes, which should decouple the sub from the floor. I was thinking of using a 3/4" sheet of MDF and putting spikes into it. Then attaching the MDF to the bottom of my subwoofer using the rubber feet on the sub or just some blue ticky-tac.


    Will this help keep the bass in a little? I don't expect to actually watch movies at reference -10db or -5db is usually the max I go, but I figured I would see what I could do so my neighbour wouldn't feel / hear anything. Good news he can't hear it!

    Next will actually be to see if he can still feel it at -10db if not great!
     
  2. Phil A

    Phil A Producer

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    You could also try a set of cones. The sub (about 70 lbs.) I am saving for the basement (when I get to it) I formerly used in my main system and the set of 3 cones (one in the front middel and two in the back corners) helped a lot with a similar problem. I think the set of DH cones I got was $50. You can also try a ceramic tile undernearth by itself (a 16x16 is usually less than $4 at Home Depot) or also with something squishly that won't raise the sub up much like those things that Home Depot sells meant to be put under kitchen table legs or Vibrapods (www.vibrapod.com, which are a whole $6 each and would recommend 3 to start placed like the cones and you will want the tile underneath so that it does not leave a mark on the floor or carpet below) or you can even look at Bright Star Isonode feet depending on the weight,
     
  3. James Bergeron

    James Bergeron Supporting Actor

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    It weighs around 90lbs! I'll look into that stuff. Thing is I find the enclosure is VERY solid, items do not vibrate on the top of it. But I do understand that energy is transfering to the floor when it shouldn't. Do you think the spike idea would even work?
     
  4. Ron-P

    Ron-P Producer

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    You can also use a slab of slate. I have a 2'x18"x2" piece under my sonosub (previously under a Velodyne CT-120) and it works great. Total cost was $20 from a landscape nursery.
    Peace Out~[​IMG]
     
  5. James Bergeron

    James Bergeron Supporting Actor

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    Out of curiosity how would slate or ceramic or anything of that nature solve / help this problem? I understand how spikes and cones would work, by reducing the surface area in contact with the floor and providing more flow for the vibrations. But tile and slate?

    Does it just increase the surface density?? My sub is on carpet on a slab.

    Thanks
     
  6. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    Here's my theory:

    With spikes the vibration forces of the subwoofer are distributed over a pinpoint surface area creating minimal vibrations in the enclosure due to it being "connected" to the ground. If the enclosure vibrates, then so must the ground due to the solid connection of 4 points.

    By using just carpet underneath the sub, the sub is lifted off the ground on a cushion of air and fiber. The sub can then vibrate and move around more because it is "floating" over the ground and not connected.

    (Take a pencil tip (spike) and hit the ground and there will be minimal vibrations in the floor, take a palm of the hand and hit the ground with the same force and there will be more vibrations in the ground)

    So my guess is that by using spikes you are "attaching the sub to the earth" so that the driver can't move the sub, making the overall sub more efficient.

    But by having the sub on a cushion of air like on a slab above carpet, your are creating a suspension in which the sub enclosure will vibrate along with the driver. This makes the sub less efficient because the driver has less throw if the enclosure moves too.

    If ppl put a tile under their sub feet they are probably creating more suspension if that tile is ontop of carpet. Unless the tile weighs a lot and isn't easily moved by the sub's vibrations.

    My sub is on a second story and since the whole floor shakes it doesn't matter if I use the feet, or the spikes because the entire ground moves.
     
  7. James Bergeron

    James Bergeron Supporting Actor

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    Chris, good explaination, so the spikes will make the sub more efficent great. But will it make it WORSE for my neighbours??
     
  8. James Bergeron

    James Bergeron Supporting Actor

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    I did a search on Audio Asylum and it seems it's a mixed bag. But from what I read spikes couple the speaker to the floor so that the floor moves not the sub! Ok so now I'm confused.

    I read awhile back in a speaker stand manual or a speaker manual (forget) that the spikes will make the speaker more solid, therefore removing vibration from transmiting through the floor rather in the air.

    Made sense at the time and to be honest with spikes on my stands I notice the floor vibrates less, which in theory to me would make me think the neighbour would hear it less.
     
  9. Greg_R

    Greg_R Screenwriter

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    Spikes couple the sub to the floor. This prevents the sub from moving around (like nailing it to the floor). You are effectively coupling the mass of the floor to the sub's enclosure... preventing the driver from moving the enclosure. This can result in lower distortion and thus less boomy bass. If your enclosure already weighs a lot, spiking may not yield major improvements. For a light enclosure w. a big forward firing driver, spikes may make a significant difference. You can get spike kits from Parts Express for a few $$$.
     
  10. Mike Poindexter

    Mike Poindexter Stunt Coordinator

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    You should get better bass from your sub, as being coupled to the floor via spikes will reduce the movement your cabinet makes from the woofer moving (each action causes an opposite and equal reaction). This will get sent into your floor, rather than into your carpet. The carpet absorbs much of the bass. This will remove that. You should get more bass, but better bass with this.

    If you want less bass, adjust the volume level on the sub. That is what it is there for. If it doesn't have a knob, then adjust it in your processor. If your processor has no bass management, then you are in a bit of a pickle.

    Mike
     
  11. Phil A

    Phil A Producer

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    Spiking the sub many times also imparts the subs location more than a non-spiked sub. This could be good or bad. Vibrapod model 5 will handle 22 to 28 lbs. per Vibrapod so that a set of 4 over a tile (so that you don't get a black mark on your floor) will not raise the sub up much and help decouple the sub from the virbrating surfaces and probably would cost about $28 so it won't break the bank. I put a set of 4 Vibrapods (model 4) under my center channel which weighs 61 lbs. and is on a bridge between my Salamander Synergy equipment racks and it seems to work quite well. I also have those rubber about 2x2 inch things that are meant to go under a tables legs (you can get at Home Depot) and put felt-like stick on material in the center so that the top is a flat surface and I use 3 of them under my rear center when I watch something in 6.1 and stick the rear center speaker on a kitchen center island behind my listening position. It definitely helps. I would try the the most cost effective option 1st since if that works, you may have resolved the problem.
     
  12. James Bergeron

    James Bergeron Supporting Actor

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    Mike, well I don't want "less" it's great! I just am trying to reduce the amount transfered to the neighbour and keep more to myself :)

    A local shop might give me some spikes for free and I already have some scrap MDF, since it won't cost anything it is worth a try!
     
  13. Phil A

    Phil A Producer

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    A no or little cost option is most definitely worth the try. Spiking a sub will make it a little quicker. The problem is that you could get some sonic interaction with the MDF vs. no MDF. Of course with a 90lb. sub it may not come into play that much. The easiest thing is to try it.
     
  14. Rob Lloyd

    Rob Lloyd Stunt Coordinator

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    I don't think spikes or anything will reduce the amount of bass passed through the walls or floors. Bass is bass, it's omni-directional it will go everywhere. If the bass shakes you or your couch, then it's certainly going to shake the floor or walls. Now if spikes or slabs or carpet reduce the enclosure vibration on the floor then that will reduce those shakes. But you're not going to stop that 20hz blast without doing an acoustically sealed room with-in a room (floating floors, seperate walls, ceilings etc).

    A boomy sealed car 20 ft away shakes my car. Isn't that car solid to the ground? I doubt the pavement is shaking enough to make my car shake or rearview mirror dance. It's the sonic blast from the car shaking my car.

    This is just my opinion so take it for that.
     
  15. Dustin B

    Dustin B Producer

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    I can only see a select few drivers having enough momentum to actually make cabinet movement a problem. Now a sub with a single or odd number of heavily waited passive radiotors, that would be a different story. But if they were even in numbers and placed antipodally then it wouldn't be a problem either.

    Even the BluePrint 1803 driver only has an MMS of 300grams. But a Passive radiator loaded with over a 1kg flapping back and forth 20 times a second, that could cause a box to move around a bit.
     

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