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AccuGroove Acoustic Isolation

Discussion in 'Amps and Cabs [BG]' started by westland, Oct 19, 2005.

  1. westland


    Oct 8, 2004
    Hong Kong
    I just purchased a new computer (Dell 9100 dual core ... a fact which is completely irrelevant to this post) and took the opportunity to try isolating my AccuGroove from coupling with the floor. I used the plastic packing to make a stand (see photos). To make a long story short, the improvement in clarity, balance and tone from this essentially free stand is just amazing. I did it after Auralex GRAMMA which we can't get over here. This is not as attractive (I may look around work for some black packing, which I know Dell uses) but it's exceptionally effective

    Attached Files:

  2. jsbarber


    Jun 7, 2005
    San Diego
    I saw Anthony Jackson play earlier this year in a club. He was using his Meyers amplified cabinets. He placed three small cones with the tip down under his sub, and then the other cabinet on top. I'm not sure who makes those cones but they would be interesting to try out. (Does anyone know where to get these things?) It looked like they elevated his cabinet about 3-4".
  3. SuperDuck


    Sep 26, 2000
    If you buy nicer cabinets for your home stereo, they will come with those. They screw right into the feet.

    I'd guess that the purpose of those is to minimize the surface area of the cab that's directly in contact with the stage. Think about it - when you place a cab on the floor, without any feet, that's a couple of square feet of direct contact. Lots of vibration. If you place those inverted cones under your amp, the amount of surface area is reduced to nearly nothing. There will be some vibration transmitted to the stage still, but it will be dramatically reduced.

    I was on an audiophile forum a while back, and they were listed as serving some other purpose, though I forget what it was they claimed those little feet would do.

    edit: Here's an answer (scroll down a bit) about the speaker spikes.
  4. jsbarber


    Jun 7, 2005
    San Diego
    I have the speaker spikes that you are refering to on my home stereo. The ones Anthony was using were about 3" in diameter at the base and the height of the cone was about 3". The tip was flattened a bit. They did not screw into the cabinet. He just placed them below the cabinet, and the weight of the cabinet held them in place. He used 3 cones.
  5. Thunderfunk


    Mar 27, 2004
    McHenry, IL
    Those spikes have the opposite effect than you think they do. The purpose is to couple the speaker to the floor, not isolate it. The reason being that you want the speaker cone to move but then you need to get rid of the internal energy it generates. You want the box to be as stiff as possible and you want that energy to leave the box and go into the floor as quickly as possible. This keeps it from interferring with the next wave. Transient response is more important than frequency response to get a natural tonality out of a speaker. Those spikes are to connect the box to the floor and to poke through the rug.
  6. westland


    Oct 8, 2004
    Hong Kong

    So are spikes good or bad?
  7. hmm, what about caster wheels on the bottom of bigger cabs.... essentially those would be doing a similar thing, probably just not as efficient?
  8. Joe P

    Joe P

    Jul 15, 2004
    Milwaukee, WI
    Well, what's the deal, then?!

    It sounds so-far like the Grama-pad is doing exactly what the spikes are designed to avoid!

    Also - I've so-far heard several TB'ers say that Gramas are amazing, but all I've ever heard about spikes is "theoretically, they're supposed to help"...

    C'mon, now! What's the story?

  9. jsbarber


    Jun 7, 2005
    San Diego
    Thanks for sharing your insights. The spikes I use on my stereo do puncture through the carpet to the wood floor below. But the ones that Anthony used did not appear to be pointed, and he used them in a room with a hard (wood or tile) floor. I'm not sure technically what's happening when he uses them, but I do trust him to have determined that they are helping his sound - by one means or another. Does anyone know what product they are?

  10. I've seen the spikes also, never could figure out what they were for. Vibration "sink" I think they call it.

    You can order sorbothane half spheres to put under the speakers to decouple them from the floor. I've tried that in boomy (cement floors, wood floor, anything that tends to really reflect sound) and they seem to help. Similar to the Gramma thing in theory.

    W.M. Berg sells them, get the harder ones for under heavy speakers, around 10, use more for heavier speaker/amp combo, less for lighter ones, more in front if weight is heavier there. There's an optimal loading "squish" you have to shoot for. Too squished, they don't have enough give left to absorb vibrations. To little weight, the spheres are too "hard", don't squish enough. 800-232-berg or 516-599-5010

  11. Big String

    Big String Supporting Member

    Apr 22, 2000
    Northwest Indiana
    Cool thing you made there. I love my Gramma's for certain situations. Great for all kinds of things.
  12. westland


    Oct 8, 2004
    Hong Kong

    I've used sorbothane in telescope mounts, and one thing to note is that there are a lot of different types, tuned to different frequencies. With telescopes you want to pick up big wiggles, so you get the stuff tuned as low as possible (subsonic). With speakers, I would guess you would want 10Hz-20KHz

    Both sorbothane and Dell-packing-othane (my model) should absorbe the vibrations from the speaker cabinet, as well as (I believe more important) raise the speaker away from the floor and prevent the boominess that floor coupling creates. In fact this is exactly what it appears to be doing in my configuration, and the effect is quite pronounced.

    The spikes, on the other hand, seem to be transmitting the vibrations to the floor rather than absorbing them, while lifting the speaker. This would seem to keep coupling of highs, while reducing coupling of lows. Do I want this?