Equipment Racks, Spikes and Stabilisation
Vibration can be called the be all and end all of hifi. It is how microphones work to record the music and how loudspeakers reproduce sound. Even turntables operate on vibrations with the grooves in the record moving the stylus. However unwanted vibrations can be a big problem and can cause unwanted side effects to the music in you listening environment.
So where do the vibrations come from? The biggest cause is usually the music itself. The louder you turn up the system, the more the music will cause vibration in the equipment. Other sources can include air-conditioning systems and traffic.
In a previous article I covered some details about vibrations to room furniture and the room itself and how it can be controlled somewhat. This time we will look more at the equipment itself and how to reduce the effects of vibration.
Loudspeakers create sound by vibrating the drivers at various frequencies. The low frequencies in particular can also vibrate the speaker box itself. Well-designed boxes will have think walls and internal cross-bracing to counteract this. However the forward / backward motion of the woofer can also cause the entire box to rock slightly in the opposite direction. This is quite undesirable, as it will cause problems with the bass reproduction, often resulting in muddiness of the sound. This is more pronounced when the box is resting on something like carpet. The bass will also be directly coupled to the floor and can cause the floor to resonate somewhat, especially if is wooden.
Speaker spikes are an excellent solution to this problem. Usually three or four are used per box and they lift the loudspeaker box off the floor by a few centimetres. Various types are available, some come with screw in bottoms, others simply stick to the bottom of the speaker. Either way, they will improve the sound. Loudspeakers should be isolated using spikes on tiled and wooden floors too, in fact many spike sets come with small protection discs to sit under the spike to avoid damaging the floor surface.
Many speakers (and of course virtually all other electronic audio equipment) have electronic components inside. Vibrations can affect these as well. The crossover parts such as capacitors and inductors (coils) can alter their values slightly plus cause small microphonic effects; especially due to the large sound pressures created inside the box. The movement of the internals of the part in question causes these microphonic effects; this movement is in time with the music. How much of an effect it has depends on the resolution of your system and the quality of the crossover components. It is also well know to affect turntables and valve equipment. Some manufacturers go as far as having the crossover mounted in a sealed and even sand filled box.
The sound waves will cause vibrations in anything they hit, including CD/DVD/SACD players, turntables and amplifiers. The first step is to isolate the turntable if you have one, as it is more susceptible to vibrations than any other type of hifi product. Any vibrations to the platter will be directly transferred to the stylus and hence it will seriously affect the playback. Many turntables come with good isolation already but more wont hurt. CD Players have suspension as well but usually not very much. Too much vibration will cause the laser to mistrack resulting in extra error correction that can be detrimental to the sound. Amplifiers are generally regarded as fairly immune to vibrations and due to their weight they are hard to shift.
Equipment racks can be a good solution to the above problems. A well-designed rack will not only look good to keep all in the household happy, but will isolate the equipment as much as possible from the unwanted vibrations, especially those coming from the floor. Various types of racks are available using many ingenious methods of isolation. Some use rubber or similar mounts, other have point supports not unlike speaker spikes. Sprung mechanisms are also used, as are magnetic platforms. Another option is to isolate each device individually. Many types of rubberised or more commonly used these days, polymer pads or ceramic legs. They sit underneath the equipment, absorbing any excess vibrational energy. Usually three are used to create a triangle, (same as for many speaker spikes) the reason is that there is then extra weight on each support point that results in even great stability. Make sure you confirm the weight handling ability of the supports to ensure they are not overloaded. That is why they often come in packs of four.
Many people have experimented with ways of controlling and isolating vibrations. Sticky tack from stationery stores can be used under speakers on stands as a means of decoupling them. Heavy stone platforms such as granite slabs have been used to add support; the heavier the weight, the less effect vibrations will have. Equipment can be placed on the slabs but be sure to take care as these slabs can scratch equipment easily, so some sort of protection between them is advised.
See you local hifi dealer and ask about the types of racks and loudspeaker spikes that are available to suit your budget. There are a huge range of models at all price points; you are sure to find one to match the level of your equipment. Ensure you take measurements and weight of your gear, these are usually found on the specifications page of the manual. The last thing you want is a brand new rack that cannot support or fit your equipment!
Written by Leon Gross, originally published in Audio & Video Lifestyle magazine.
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