silicone feet or spikes for my rack

gtimadman

Standard Member
Hi guys got myself one of these racks called a quadraspire

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it has adjustable feet to go through the carpet to the floorboards.
But my question is, my cd player amp etc on the shelves should they be on granite blocks spike or silicone feet bit confused here :(:blush:
 

Don Dadda

Distinguished Member
If this is to keep the components stable and suck up vibration, try some blu tac. Does the same job very effectively.
 

paulktreg

Active Member
Forgive my ignorance but I thought this sort arrangement was only useful when using a turntable to prevent vibration. I've heard of turntables having granite bases but nothing else. Is this sort of arrangement still useful for CD players etc?
 

BlueWizard

Distinguished Member
Pretty much every device must act in two ways, one is to not transfer sound out other then in intended ways. The second is to not absorb sound in unintended ways.

For example, you don't want vibrations of the CD Motor and read mechanism to be transferred out into the stand or other nearby equipment. The assumption is that any vibration that is transferred is lost to the mechanism. This analogy works better for speakers; any movement in or of the cabinets is a loss of movement to the cones. At the same time you don't want outside vibrations, say from the speakers, transferred in to the motor/read mechanism of a CD.

Now, virtually any component has the potential to be microphonic. This was most apparent in old Tube/Valve amps, if the speakers shook them hard enough, that vibrations would be transferred to the anode, cathode, and screen of the tube/valve and create a small signal that was then passed through the amps to the speakers.

This is less of a problem with solid state equipment, but even it has the ability to be 'microphonic'.

So, sound and vibration can be transferred into and out of equipment in many unintended ways.

Sound waves can vibrate the turntable tonearm, which causes a rumble which is then transferred to the speakers, which in turn is then transferred to the tonearm, and around and around it goes, until you have a deep rumbling feedback.

I've also experience circumstance in which the air in the room was moving so severly, that it actually cause the turntable box (stand, plinth, whatever...) to resonated which cause the turntable platform to bounce around wildly.

In some case, you want a stand or a speaker as tightly coupled to the floor as possible, hence concentrating the weight on sharp spikes. But, if that coupling is simply going to drive sound down into the floor, and cause the floor and/or room to resonate, that's not helping. In this event where the speakers are actually making the floor resonate, instead of coupling, you want isolation.

Those who use large heavy solid blocks of granite, are using mass isolation. Presumably, the granite has so much mass that a given vibration has come and gone before it has a chance to overcome the inertia of the block.

Soft rubber-like pods prevents the mechanical transfer of vibration in either direction. But, there is a limit to how much vibration they can absorb. For example, they wouldn't be of much help in an earthquake :) . But, while they dampen mechanical transfer, the do little to dampen acoustical transfer.

Also, keep in mind that a lot of these gadgets are predominantly meant to part you from you money.

Also, also, like so many things, their usefullness is based on their cost as a proportion of the total cost of your system. If you have massive amp, and ultra-precision players, all costing a king's ransom, then every little detail is noticable. With equipment of this high caliber every flaw in the room, every subtle secondary vibration is noticeable. However, if you have common, though nice and somewhat expensive, consumer equipment, you don't necessarily need £500 power cables or £5000 speaker wires; nor do you need extremely expensive pointy things or soft squishy things.

Mostly want you need is a good solid free from wobble cabinet, good solid not bouncy floors, and a huge dose of common sense.

Specific to your circumstance, I would evaluate just how solid and immovable that stand is. If it seems pretty solid, then you need to examine the placement of the speakers relative to the equipment and equipment stand, and determine if the most significant vibrations is going to be mechanical transfer, meaning up through the floor, or if it is going to be acoustical transfer, meaning through the air.

And if through the air, is the air movement most likely to move the stand, or the equipment on the stand?

For mechanical transfer up from, or down into, the floors, I would say the soft squishy rubber-like feet might be worth a try.

If you have really and truly solid floors, and a pretty structurally solid house/flat/whatever, the definitely spike the stands and the speakers to the floor. However, if you have a floating floor, or a not so solid bouncy floor, then I think some type of isolation is the best choice. You need a soft barrier under you stands and speakers to stop the vibration from traveling in either direction.

And lastly and sadly, what I have said is only the tiniest barest amount of information regarding isolation and coupling. It is an art and a science in itself.

Aren't you glad you asked? ;) .

Steve/bluewizard
 

gtimadman

Standard Member
wow thanks dude kinda makes sense too the floor is floating i.e floorboards but they are screwed down well
 

ozzzy189

Distinguished Member
Another interesting post from the blue wizard. All i know is, rubber feet under amps and cd players etc is bad, it stores the energy in the components that needs to be dissipated. Squash balls are made of rubber and are designed to store this energy making them dead with little bounce. Wood is a much better material for isolation feet. So why do most manufacturers use it? Don't ask me, i haven't got a clue.
 

BlueWizard

Distinguished Member
I'm not a 100% sure I agree with ozzzy189, but is does make some vaild points.

The problem with soft squishy supports is that they tend to flex.

Let's say the read head on a CD (though more accurately, it would be a hard driver, but still for illustration purposes...) suddenly moves to the side. If the CD is mounted rigidly to the stand, say with spikes, the CD Case is not going to move. But if is in on squishy pods, the entire device will have some lateral movement on the pods. We really don't want the CD box flopping around while the head is trying to track.

Now realistically, the real read head on a CD is never going to make that drastic a move. But, it illustrated a point. The 'pods' will not allow that mechanical movement to be transferred down into the stand, which is their purpose, but at the same time, they can exaggerate mechanical movements within the device itself. Keep in mind, all this is very subtle.

We had one member who had nice speakers but they were on suspended or floating wood floors, and the resonance was causing a problem. He build some sand filled boxes, which, being soft mass, did not transfer vibration very well, and mounted his speakers on the boxed, with Polypods in between, and that solved his problem, and didn't adversely effect the sound of his speakers.

The point? It is difficult to know what to do in any given situation, and even more difficult when your only access to the problem is through electrons flying over the Internet.

You really have to give some long hard thought to your room, your equipment, and your goals. Do you want to stop vibration from transferring into and out of your stands? And is that transfer of vibration into and out of the floor the problem? Or is the real problem, transfer into and out of your speakers and the floor? In other words, do you need to fix your stands or your speakers?

Also, is the problem between the equipment and the floor, or the equipment and the stand? For example, if you speakers are causing your floor to resonate, you an fix your stands from now to high heaven, and the problem won't be solved.

Generally, if you have a very solid stand, then the stand itself is not going to be a problem. In this case, just setting the equipment on the stand shouldn't be a problem.

And, if the problem is between the speakers and the floor, then that is the problem you need to work on, not the stands and the equipment.

So, is there a problem that actually needs to be solved?

Next, exactly what and where is that problem? Because, we need to fix the problem at the source.

Once you've isolated the problem, then we consider the possible solutions, and which work best in this specific case.

If the problem is vibration being transferred up into the stands and therefore the equipment, then isolation pods or similar. But, one must consider if that is the actual problem, or if that is the symptom?

And keep in mind, once you have considered all the mechanical transmissions of vibration, you still have to consider acoustical transmissions of vibrations. Both of which may or may not be a problem at all.

So, best to make sure you have a problem, before you try and solve it.

Just rambling.

Steve/bluewizard
 
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Mr Pig

Well-known Member
It doesn't matter what the theory is. I doubt we understand the half of it anyway. Try everything, go with what works.
 

gtimadman

Standard Member
Cheers guys you may laugh but i don't actualy have a problem as i havn't set it up just yet, what im trying to do while build the system is to 'build in' and factors that could help in anyway while the rooms being literly made .

The stand is very heavy and solid and is apparently designed in a non square shape to help stop resonations , some of my seperates have very hard feet i would have thought that going onto the cherry might make them rattle as the rack will be quiet close to front left speaker, also to this end as its quiet close to the speaker i dont want vibrations from the speaker interfering with the dvd and cd players ....

Thanks again
Andy
 

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