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Optimum Tennis Balls for Isolation Riser?

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  • Optimum Tennis Balls for Isolation Riser?

    Hi everyone,
    I remember seeing a comparison of different tennis balls used for an isolation riser on here, but I can't seem to find the post now. I've read the threads/searched on here, including MisterMr's build plans and all billion of the responses and I also came across this link:
    http://www.itftennis.com/technical/e...alls/index.asp

    This looks like the most reliable comparison of different types of tennis balls, so I'm wondering if anyone has tried stage 2 or stage 3 balls and what your experience has been with them? It seems like stage 3 balls would give the softest suspension, which should give the best noise isolation, but I wonder if they are too soft and cause the kit to "rock" too much during playing?

    My plans are very similiar to MisterMr's... rubber feet to the floor, a chip board sandwich with tennis balls (but also adding foam) and then some carpet padding and carpet over the top... and a cut out to fit my lunar roc-n-soc (the throne will be on the floor, not the platform).

    The idea of the build is to make the suspension as soft as I can (without having too much sway of the kit), which I expect to spread out the impact energy from the kick and hi hat. then hopefully the foam will absorb any added acoustic noise generating from the stage (soundboard).. and finally the rubber feet to mimize direct contact with the flooring (I expect this should act as a high pass filter, for the problematic low frequency vibrations).
    TDW-20 (v2.51)
    VEX packs: Program 3
    VST packs: not yet

  • #2
    Well, if one wanted to really get into it, then you'd need to determine what's the total live load, what's the point load at each isolator (i.e. tennis ball), what frequency range of vibration is being isolated and then what's the static deflection of the tennis ball(s) when the load is applied. Too soft = too much compression and no isolation...too stiff = no compression and no isolation.

    All that being said, I think it's probably unnecessary to get too nuts about what the "ideal" tennis ball is. Technically, you shouldn't have 2 points of isolation: the tennis balls and the rubber feet. This is because there's actually potential for some of the frequencies deflecting both isolators and causing cancellation, therefore technically creating a short circuit path. However, this is more common in very constant vibration induction, like from a rotating machine/motor. It is probably fine in this scenario...though I wouldn't personally do it. But that's me.
    Stick twirling - because you obviously have mastered all other aspects of drumming already, right?

    Comment


    • #3
      Originally posted by dschrammie View Post
      Technically, you shouldn't have 2 points of isolation: the tennis balls and the rubber feet. This is because there's actually potential for some of the frequencies deflecting both isolators and causing cancellation, therefore technically creating a short circuit path. However, this is more common in very constant vibration induction, like from a rotating machine/motor. It is probably fine in this scenario...though I wouldn't personally do it. But that's me.
      It's easier for me to think of this in terms of an eletrical circuit analogy. I see an impulse response of a filter system. The impulse being the impact energy of the bass/hihat pedal and the isolation platform as the filter. The rubber feet and the tennis balls make up a two stage high pass filter. This might be an over simplification (it's actually a full network of passive filters), but it does seem that the rubber feet would have some effect.

      but you're right, emperical results are better and faster than making simplifications and assumptions... so I'll just use stage 2 balls (could easily switch to stage 1 if needed) and see how it goes.

      There are too many factors to really compare designs on something like this.. but I was hoping to get an idea of how much of a stability difference each "stage" of tennis balls make.
      TDW-20 (v2.51)
      VEX packs: Program 3
      VST packs: not yet

      Comment


      • #4
        I strongly suspect it wouldn't matter which balls you used, there would have to be a huge variation between the stages to make much difference I guess.

        I would say in my build using 8 balls in a 3-2-3 pattern on a 4x3 foot platform I've found it to be quite bouncy. In fact i'm sure the bounce is getting worse, though that could just be from learning to play better. Sometimes i'd swear hitting certain combination of pads at regular intervals starts to set up self-oscillation within the system Its not so bad on the pads, its having the kick pedal bounce or sway that I find disconcerting.

        Basically don't expect TB platform to solve all your noise issues straight off, it wont, though I do feel it makes a big difference in my case and secondly don't expect it to be rigid. However if you can invest time and money you can probably build better versions with experience and testing out variations such as num tennis balls, platform weight etc.

        I like the idea of putting foam inside, its something I wanted to try as the sandwich does tend to 'echo' somewhat. Though i'm now also wondering how to make it less bouncy.

        Good luck with it and don't forget to post your build and any 'findings' you make in the main thread.

        Edit:
        I don't think the bounce is strictly from the tennis balls, more due to just using a few non-fixed tennis balls sitting in holes in the MDF, I think that gives it a wobble. Actually I guess there are two aspects to this, wobbles (horizontal) and bounce (vertical)

        Also I may not sound happy with my TB platform, but actually I am, at least its a million times better than using 4 settee foam cushions, they were bouncy but worse had no support, so just sagged. They did get rid of most of the direct vibration though
        Last edited by noisecrime; 11-10-10, 07:46 AM.

        Comment


        • #5
          Originally posted by noisecrime View Post
          I like the idea of putting foam inside, its something I wanted to try as the sandwich does tend to 'echo' somewhat. Though i'm now also wondering how to make it less bouncy.

          Good luck with it and don't forget to post your build and any 'findings' you make in the main thread.

          Edit:
          I don't think the bounce is strictly from the tennis balls, more due to just using a few non-fixed tennis balls sitting in holes in the MDF, I think that gives it a wobble. Actually I guess there are two aspects to this, wobbles (horizontal) and bounce (vertical)
          Thanks for sharing your experience... when you talk about wobble I wonder if you have a mis-alignment problem? Did you use one board as a stencil for the other board, when cutting your holes? (to make sure they align) Maybe even making your holes SLIGHTLY larger might help? (if the holes are too small, the platform won't be as stable... if anything the guy who used velcro instead of holes, should have the biggest problem with this (if that is the cause).

          The foam I'm using may help reduce wobble a little bit... but mostly it's to reduce the additional acoustic noise you mentioned. I'll probably put it together this weekend (took all the measurements I need for my throne cut-out last night).
          TDW-20 (v2.51)
          VEX packs: Program 3
          VST packs: not yet

          Comment


          • #6
            Originally posted by aguyinca View Post
            Thanks for sharing your experience... when you talk about wobble I wonder if you have a mis-alignment problem? Did you use one board as a stencil for the other board, when cutting your holes? (to make sure they align) Maybe even making your holes SLIGHTLY larger might help? (if the holes are too small, the platform won't be as stable... if anything the guy who used velcro instead of holes, should have the biggest problem with this (if that is the cause
            Got my holes perfect and was very proud of myself
            I bought a hole cutter (38mm diameter) especially for the job (best decision ever made), screwed both boards together and drilled through.

            It did take a long time, there were a number of problems, firstly it eat through my 18v cordless drill batteries within about 10-15 minutes and I think I needed 3 charges in the end to do all 8 x 2 holes.

            I was actually quite lucky though that the 'bit' fitted this drill as two corded drills I borrowed (one old, one new) wouldn't accept the bit at all, its shaft being too thick to fit! I don't think there was any choice on the shaft thickness for the hole drill bit, other than switching to a smaller diameter hole.

            It also took time as you need to stop every minute or so to remove sawdust from the hole, else the whole thing gets bunged up. i had my vacuum on hand nearby, perfect for the job.

            One other thing, don't just mark your holes based on some abstract values (e.g. 100mm in from the edge), until you've placed your kit onto the board and checked where its legs will be, otherwise you may end up with them practically on top of the tennis balls!

            Thinking about the wobble a bit more, it is horizontal but not left/right, only forward backwards (when sitting at the drums). In fact it may be caused more by compression, as standing on the edge near the throne the platform compresses quite a bit, making it slope towards you. Its not enough to make the kit unstable, but i think its this compressing that causes the wobble when playing, even though the kick pedal is almost in the center of the platform.

            All said and done, I did enjoy the project and it does make a big difference. I've yet to find any suitable foam or padding to place on top of the platform, just some thin old carpet. I think getting some type of foam mat would probably help stabilize and reduce impact noise even further.


            Edit: Hole size
            Funny I seem to remember being somewhat concerned with the size of the holes when I made them, thinking they were too small. Though via touch using 38mm dia hole I can feel the top of the tennis balls no more than 5mm below the top of the board, so they do sit quite well in the holes.

            Comment


            • #7
              Originally posted by noisecrime View Post
              Got my holes perfect and was very proud of myself
              I bought a hole cutter (38mm diameter) especially for the job (best decision ever made), screwed both boards together and drilled through.

              It did take a long time, there were a number of problems, firstly it eat through my 18v cordless drill batteries within about 10-15 minutes and I think I needed 3 charges in the end to do all 8 x 2 holes.

              I was actually quite lucky though that the 'bit' fitted this drill as two corded drills I borrowed (one old, one new) wouldn't accept the bit at all, its shaft being too thick to fit! I don't think there was any choice on the shaft thickness for the hole drill bit, other than switching to a smaller diameter hole.

              It also took time as you need to stop every minute or so to remove sawdust from the hole, else the whole thing gets bunged up. i had my vacuum on hand nearby, perfect for the job.

              One other thing, don't just mark your holes based on some abstract values (e.g. 100mm in from the edge), until you've placed your kit onto the board and checked where its legs will be, otherwise you may end up with them practically on top of the tennis balls!

              Thinking about the wobble a bit more, it is horizontal but not left/right, only forward backwards (when sitting at the drums). In fact it may be caused more by compression, as standing on the edge near the throne the platform compresses quite a bit, making it slope towards you. Its not enough to make the kit unstable, but i think its this compressing that causes the wobble when playing, even though the kick pedal is almost in the center of the platform.

              All said and done, I did enjoy the project and it does make a big difference. I've yet to find any suitable foam or padding to place on top of the platform, just some thin old carpet. I think getting some type of foam mat would probably help stabilize and reduce impact noise even further.


              Edit: Hole size
              Funny I seem to remember being somewhat concerned with the size of the holes when I made them, thinking they were too small. Though via touch using 38mm dia hole I can feel the top of the tennis balls no more than 5mm below the top of the board, so they do sit quite well in the holes.
              Good point about the tennis ball location, I was going to do a mock setup as you mentioned to make sure I don't pass vibrations straight through the tennis balls. I haven't worked out just where to put them yet, just the cutout I need for my throne to fit up close (I have a lunar, which has 5 legs... so a cutout is a must).

              I wonder if what is causing your forward/back sway is pushing into the bass pedal a bit. Like what causes your drumset to creep forward if you don't have carpet spikes or rubberfeet (on hard surfaces). Maybe if you don't have a cut out for your throne it's causing you too sit a little too far back and is pushing into the kick more? Just an idea, maybe try sitting forward as much as you can and see if it helps? It's inevitable you'll always be pushing into the drums a bit, but maybe it can be reduced.

              Also, why not use carpet padding for your top layer? I haven't priced it yet, but it must be cheaper than foam mats.
              TDW-20 (v2.51)
              VEX packs: Program 3
              VST packs: not yet

              Comment


              • #8
                Originally posted by aguyinca View Post
                I wonder if what is causing your forward/back sway is pushing into the bass pedal a bit.
                More than likely had been thinking the same, but not sure I want to move further forward. Certainly there is some room to do that and i could just as easily move the kick pedal towards me, but I do feel comfortable with the current position.

                Might be interesting to try though, to see if my kick pedal playing improves as somethings not quite 'right' with it at the moment, or i'm just rubbish

                Also, why not use carpet padding for your top layer? I haven't priced it yet, but it must be cheaper than foam mats.
                Thick foam mats will add additional weight (but still means the platform can easily be moved in sections) which I would assume would absorb more vibrations, as well foam being good at reducing vibrations anyway.

                The difficulty for me is finding the right foam mats without high price tags and available in the uk. I seen suggestions from gym mats, camping mats even horse mats!

                I'd feel wary of doing a cut-out for the throne, to me that would suggest the whole platform being structurally weakened and you'd probably need to use quite a few more tennis balls to ensure stability. I seem to remember in the main thread it being said that too many balls hurt the absorption.

                Can you not simply make a separate throne section that butts up to the main platform, then the throne can simply straddle both parts?

                BTW - please don't feel I'm giving 'expert' advice here. My DIY skills are minimal (thus being very proud that my platform didn't just fall apart first time i used it). Really just passing on some tips from when I built one and then my opinion on other matters
                Last edited by noisecrime; 11-12-10, 01:24 PM.

                Comment


                • #9
                  Originally posted by noisecrime View Post
                  I'd feel wary of doing a cut-out for the throne, to me that would suggest the whole platform being structurally weakened and you'd probably need to use quite a few more tennis balls to ensure stability. I seem to remember in the main thread it being said that too many balls hurt the absorption.

                  Can you not simply make a separate throne section that butts up to the main platform, then the throne can simply straddle both parts?

                  BTW - please don't feel I'm giving 'expert' advice here. My DIY skills are minimal (thus being very proud that my platform didn't just fall apart first time i used it). Really just passing on some tips from when I built one and then my opinion on other matters
                  .haha thanks for the disclaimer
                  I like the idea of the throne being off the platform.. one for stability, and second I agree that if you sit (even partially) on the isolated platform, it seems you will reduce it's effectiveness. It seems adding more weight to the top platform is equivalent to using a stiffer suspension... which would reduce the effectiveness. (think of a car with bad shocks... all of the vibration is passed straight through to the passengers).

                  I don't think a cut out will hurt the structural integrity of the platform at all. Think of all of the force vectors running orthogonal to the platform. I'm planning on using 12 balls with 3/4" chip board.. if this is overkill, I can always take out a few balls as long as the chip board has enough support.

                  I'll put it together this weekend and post the specs on the main thread after i test it out.
                  TDW-20 (v2.51)
                  VEX packs: Program 3
                  VST packs: not yet

                  Comment


                  • #10
                    I posted my build on the main forum if you want to check it out... The platform doesn't wobble at all, but I do get bounce particularly for the snare and hi hat (from the hi hat pedal). It's not bad enough to affect my playing though. It does help the noise some, but I'm still worried the neighbors might get some transmission.. if I come up with any improvements (such as better tennis balls or GreenGlue) I'll put them in the main thread... Thanks for the suggestions.
                    TDW-20 (v2.51)
                    VEX packs: Program 3
                    VST packs: not yet

                    Comment


                    • #11
                      Wouldn't one think that DEAD tennis balls would be best?!

                      My nephew plays varsity level in HS and these kids are so strong these days that they break strings and kill balls weekly. I could get a boatload of spent tennis balls if I asked...

                      Comment


                      • #12
                        Originally posted by wolfereeno View Post
                        Wouldn't one think that DEAD tennis balls would be best?!

                        My nephew plays varsity level in HS and these kids are so strong these days that they break strings and kill balls weekly. I could get a boatload of spent tennis balls if I asked...
                        Hmmmm....interessting. I didn't know you could "kill" a tennis ball. What's the differencce?
                        8 Piece Smokey Chrome/Acrylic w/DIY Pans http://quartzpercussions.com/home_en.html 2BoxDrumIt5x2, DIY Acrylic Spl/Ch, Gen16 Hats/Rides/Ch/Spl, Assorted Gen16 Conversion Cymbals http://www.stealthdrums.com/,DW Remote,SleishmanTwin/QuadSteele Conversion, http://www.drumagination.com/drum-pe...com/mk_pro.php Gibraltar & DrumFrame rack systems
                        www.airbrushartists.org/dreamscapeairbrushrealm

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                        • #13
                          I've never needed one, but here are some risers others have created:





                          TD-20exp module/TD-10exp * VH-12 hh * Gibraltar hh stand * 4 Hart Hammers * 2-22" kicks w/Pintech triggers & Blastech mesh * 1-14" snare w/Pintech triggers & Hart mesh *2-10", 2-12" & 2-14" roto toms w/Quartz triggers & Hart mesh * 7 PCY-150 cymbals

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                          • #14
                            Tennis balls loose their bounce after being played for a while. Especially when the players hit hard. They're still pretty firm but I guess they loose some of their internal pressure.

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                            • #15
                              The tennis balls in my platform have kept their strength for about 2-3 years now. When I made it, I went with a few extra tennis balls near the throne and the kick pedal. There may be a touch of movement, but nothing that I am worried about.

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