NorStone Acoustic Metal Beads
Complementary products
Overview
A hollow metal tube rings like a bell when struck, and the uprights of a hi-fi rack or a speaker stand are no exception. This 3 kg bag of metal beads is used to fill these structures to make them heavier and more inert beneath your equipment. The principle is long-established and easy to put into practice, and it remains reversible: simply empty the tubes to undo it.
A heavier, more inert support beneath your equipment
A speaker placed on a stand transmits its vibrations to the structure supporting it. If the stand is light and hollow, it begins to vibrate itself, and these unwanted movements become mixed with the sound, particularly in the bass and lower midrange. The same logic applies to a hi-fi rack, whose uprights pick up vibrations from the floor, speakers or the mechanism of a CD player or Blu-ray player. Filling the tubes increases the mass of the whole structure: more energy is needed to set it in motion, and its stability on the floor improves accordingly, making a weighted speaker stand much harder to tip over.
The beads provide a second effect that a solid, single-piece weight does not. When the tube vibrates, they rub and collide with one another, and this movement dissipates some of the vibrational energy as heat, in a tiny amount but enough to damp the metal’s resonances more quickly. This is known as granular damping. The difference can be heard when tapping by hand: a filled upright produces a dull sound, whereas the empty tube rang clearly. The benefit obviously depends on the starting point, with a lightweight structure benefiting more from added weight than a rack that is already heavy and rigid, and it is no substitute for good speaker placement or work on the room’s acoustics.
Fine 2 to 4 mm beads rather than sand
The beads measure between 2 and 4 mm in diameter. This size passes easily through the filling openings and reaches the bottom of the tubes, filling corners that larger pieces would leave empty. The mix of sizes helps create a denser fill, with the smaller beads settling into the gaps left by the larger ones.
Dry sand remains the most widespread weighting solution, and metal differs from it in several ways. For the same volume, it weighs considerably more, putting more mass into a tube of a given cross-section. It does not release fine dust when poured and does not form clumps over time, unlike poorly dried sand that has absorbed moisture. The beads also flow freely when the tube is turned upside down, making it easy to empty when you move home or change racks.
How many bags to allow for a Spider rack
NorStone states that one 3 kg bag fills half the tubes of one shelf: two bags are therefore needed to fully weight one level. The brand primarily recommends these beads for its Spider range of modular racks, each of whose legs is hollow and accessible from the top. The damping pads at the top of the uprights unscrew to reveal the filling opening. The modules are not all the same height (12 cm for the Spider Base, between 23 and 36 cm for the Spider 1, 2 and 3 shelves), and the quantity of beads varies accordingly: a base requires fewer than a Spider 3.
The beads are equally suitable for speaker stands and TV stands from other manufacturers, provided their columns are hollow, have an accessible opening and are closed at the base. An open or poorly sealed bottom would let the beads escape from below, so it is worth checking this before starting.
Fill the tubes neatly in just a few minutes
The procedure is carried out with the rack empty and the equipment removed. After removing the pad or cap from the upright, pour in the beads using a small funnel or a sheet of paper rolled into a cone, tapping the tube from time to time to settle the fill. It is best to stop a little below the edge so it can be closed without forcing it. Filling all the uprights on the same level to an equal height keeps the rack balanced, without one leg carrying more weight than the others.
The added weight has a practical trade-off: a weighted rack is harder to move. The simplest approach is therefore to fill it once it is installed in its final position, with cabling in place, rather than moving it afterwards when loaded.
Technical Specifications
Dimensions and Weight
- Bead diameter: 2 - 4 mm
- Net weight: 3 kg
Specifications
- Material: metal
- Packaging: bag
Application
- Use: vibration absorption
Frequently asked questions
With just one bag, which uprights should be weighted first?
Two approaches coexist. For overall stability, the base is the first level to fill, as mass placed closest to the floor lowers the centre of gravity of the entire unit. For listening, the shelf supporting the source most sensitive to vibrations, primarily a turntable, followed by a CD player, deserves priority. In both cases, distribute the bag’s contents evenly among the four uprights of the chosen level rather than filling two legs to the brim and leaving the other two empty.
Is one bag enough for a pair of speaker stands?
It all depends on the internal volume of the columns, which varies considerably from one model to another. The safest method is to divide the first bag into two equal portions, one per stand, check the level reached, then top up if necessary. Both stands must receive the same amount so that the speakers rest on identical supports.
Do the balls make noise inside the tubes?
When stationary, no. Tightly packed filling limits movement between the beads, and the tube remains silent, even at high volume. A half-filled tube may produce a slight sliding sound if the furniture is moved, which does not happen during normal use.
Can the balls be reused for another piece of furniture?
Yes. Simply turn the upright upside down over a container, or over a funnel placed on the original bag, to let the beads flow out. They do not wear out and can be reused indefinitely, making this a purchase that stays with your setup from one piece of furniture to the next. Keep the bag for that day.
Does the extra weight pose a problem for the floor?
Two bags amount to 6 kg per shelf, distributed across four feet, which remains reasonable for most floors. If the unit rests on isolation spikes, however, the load is concentrated on a very small area: on parquet, vinyl flooring or delicate tiles, spike shoes prevent marks and keep the spikes from slipping.
Is there any benefit to adding ballast to an already heavy piece of furniture?
It has less. A solid, rigid piece of furniture has little resonance to begin with, and adding ballast offers only a modest improvement. On a lightweight tubular structure, or on a speaker stand that sounds hollow when tapped with a finger, the effect is much more noticeable. The tapping test also gives a good indication before you even begin.
- Eco-contribution included in the sale price.
- Manufacturer reference: NORMETBEAD
- GTIN / EAN: 3700795180242
