Using Nails as Speaker Spikes? (1 Viewer)

[James Zos]

Okay, I'm afraid this post is going to look a little ridiculous, and maybe it is. As the thread states, I want to know if I can use ordiary roofing nails as speaker spikes.
I have homemade wooden stands, and am thinking about putting four nails in each, and letting my speakers rest on the nail heads to keep the sound from traveling through the stands, which were not exactly designed with acoustics in mind.
Is that crazy? Will this method negate the benefit I'm trying to achieve? Any responses welcome, I guess.

 

[Ted Lee]

very interesting idea...
i'm not sure it would work in theory though. you'd have to ensure that there is even distribution among *all* the nail heads. essentially you'd have to spread the load 16 times (4 per leg) instead of just four times. sounds kind of tricky...

Will this method negate the benefit I'm trying to achieve?

depends on what you're trying to achieve. if you're not already aware, the purpose of spikes is to "couple" the speaker to the floor...providing a rigid mass to go "against" the cone. essentially forcing the cone to move and not the speaker.

 

[James Zos]

Okay, let me officially admit I have no idea what I'm doing.

I thought the purpose of spikes was to prevent the sound from resonating through whatever the speaker was sitting on. In other words, the sound has a harder time traveling through the thin body of the spikes and into the stand, as opposed to just placing the speaker on the stand. But, obviously, that is incorrect?

Thanks for your response, Ted!

 

[Chu Gai]

Myself, I'm not a fan of spikes as all they seem to do is poke holes into things. If I understand you correctly, you're looking at taking your homemade speaker stands, tapping some sort of wide head nails into the top and resting the speakers on top of those. If that's correct, that sounds like you're creating a potentially very precarious situation with a very distinct possibility of the speaker sliding off. Building supply centers and hardware stores sell these self-stick rubber disks in a variety of diamters. Those have a higher coefficient of friction and will more securely hold your speakers. Putting a piece of cork cut to fit, or even something like 'ice dam' (bought in rolls at say Home Depot...used for roofing) will also act as high friction interfaces.
With all due respect to spikes acting to prevent speaker movement, if you work out the physics of what's involved here, you'll find it just isn't so. Aesthically, they can look kind of nice, but damn they do poke holes and mess up nice wooden floors.

 

[James Zos]

Thanks for the response, Chu!

That's a great sig, by the way.

 

[Ted Lee]

With all due respect to spikes acting to prevent speaker movement, if you work out the physics of what's involved here, you'll find it just isn't so.

oh yeah???? well...what if it was a really really big woofer? then what mr smarty pants?
actually i agree with chu on this point. i only described what they're supposed to do.

 

[Chu Gai]

wanna see some physics behind it with #'s and all? said strictly in the spirit of information Ted. The prices that are charged for these things is preposterous but I like what's going on over in the DIY area where one member is looking at making them for some people. Me, I'm waiting to get some made out of depleted uranium.

 

[Ted Lee]

chu...that would be great.
i've always been more of a doubter than a believer when it comes to tweaks, but i like to see both sides of the coin.
bring it on!

 

[Chu Gai]

I'll work up #'s later this evening

 

[Chu Gai]

Well to calculate how much a speaker would move, we need to determine the momentum that occurs when a driver moves. Newton's third law says that momentum must be conserved. Yeah, it's that nasty old science rearing it's head again but it seems to work pretty well. Book knowledge
For the sake of simplicity, let's consider something like the Paradigm Studio 60's (each speaker assembly weighs 50 kg). That's got an 8" woofer. Let's assume that the weight of the cone that moves back and forth is 25 grams. Further let's assume that at 40 Hz that cone is moving 1 cm. We can calculate the velocity as follows:
v = (2 pi) (f) (Xmax) = 6.28 *40/sec * 1x10^-2m = 2.51 m/sec
Momentum is mass times velocity
momentum = m * v = 2.51 m/sec * 25x10^-3 kg = 0.0628 kg m/sec = 6.28x10^-2 kg m/sec
From Newton's third law, momentum is conserved so...
mv(woofer) + mv(entire speaker) = 0 or mv(woofer) = -mv(entire speaker)
Let's substitute the values in our example...
6.28x10^-2 kg m/sec = -mv(entire speaker) = -50 kg * v(entire speaker)
v(entire speaker) = -0.0013 m/sec or -0.13 cm/sec
Now keeping in mind that the woofer is vibrating at 40 hz = 40 times/sec.
(0.13 cm/sec) / 40 hz = 0.003 cm
That's 3 thousandths of a centimeter...30 millionth's of a meter. That's how much the speaker will move under those conditions when it's on a frictionless surface. However carpets and floors most assuredly have friction and enough to effectively stop that speaker from moving.
If you don't like my numbers and can obtain actual numbers from say Paradigm, feel free to substitute accordingly.
So what is there to be said when people say spikes somehow affected their sound? Illusion? Maybe raising the speaker an inch or two caused it to interact slightly different with both your ears and the reflecting surfaces? You want to spend $50 or a few hundred on something like that? Knock yourself out. Me, I'd drop it on some room treatments or something.

 

[Ted Lee]

If you don't like my numbers and can obtain actual numbers from say Paradigm, feel free to substitute accordingly.

lol. chu...i wouldn't know if those numbers were the truth or if you were throwing a hunk of poop my way. however, i do trust you so i'll take your word for it.
.0003 cm - who knew!
ps - thx for running those numbers!

 

[Chu Gai]

I think the boys over at DIY would have some actual #'s seeing as how some are into serious speaker building...keep in mind, that's the movement if there's NO friction.