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PS audio explain how spike at bottom of the speaker works

gerG

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The answer is, of course, it depends. The original idea behind the spikes is that they couple to the floor, preventing the speaker cabinet from vibrating counter to the cone motion. If this happens, one woulh have out of phase signal cancelling the "correct" signal. Probably works for a sealed cabinet running at low frequency with concrete floors and carpet. It get more vague with bass reflex ports and wooden floors. How to tell what is best? Easy, run a test! Easy enough to put a mic in front of the speaker and do a response sweep, or even pink noise with an RTA. Try with and without. Next level is a vibrometer on the speaker cabinet. More difficult to find, but you could figure out the resonance frequency of your speaker/stand combo. The toughest one is something like Newman's LSR6325P on a tall stand. Those are heavy aluminum cabinets (I have several pairs) and they make a great pendulum. Fortunately they are going to rock, er. oscillate at a low frequency. Keep your crossover above that, and it does not matter much. Taller stands and heavier speakers push the resonance to a lower frequency.
There is a company called Isoacoustics that make stands designed to let the speaker vibrate in space. Their intent is to decouple the speaker from a desk or console to eliminate annoying vibrations. They work for that. I am ashamed to admit that I have not tested them to determine the sonic impact. The company rep told me that they actually improve the sound. I doubt that, but without data I can only conjecture. As far as desk stands go, I really like them.
 

Newman

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The original idea behind the spikes is that they couple to the floor, preventing the speaker cabinet from vibrating counter to the cone motion.
But they don't prevent that. It's a false premise, like I said.

Fortunately they are going to rock, er. oscillate at a low frequency. Keep your crossover above that, and it does not matter much.
The pendulum Fs for my setup is about 2 Hz back-and-forth, 1 Hz side-to-side. They could be subwoofers and it wouldn't matter, in terms of rocking in response to cone motion. My point.

And if I had spikes, it would prevent nothing: those Fs values would be the same, except it would rock back onto the rear spikes, then (Ker-lunk) onto the front spikes. Which would only be worse. Fortunately it's a false premise.
 

gerG

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But they don't prevent that. It's a false premise, like I said.


The pendulum Fs for my setup is about 2 Hz back-and-forth, 1 Hz side-to-side. They could be subwoofers and it wouldn't matter, in terms of rocking in response to cone motion. My point.

And if I had spikes, it would prevent nothing: those Fs values would be the same, except it would rock back onto the rear spikes, then (Ker-lunk) onto the front spikes. Which would only be worse. Fortunately it's a false premise.
In your case, I agree. I was guessing about 5 hz, but my calibration must be off.
However, take a system with a light cabinet and a large low mounted woofer or PR, sitting on carpet. No longer a pendulum, but a block sliding back and forth. It is possible, I think, to hit frequencies where the cabinet moves and creates energy losses. You can actually see this in some subs with undersized cabinets.
One real practical application of spikes is wobbly speakers. They are dandy for stabilizing a cabinet that moves around from floor movements.
 

Newman

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How many pro Subs have you seen that dig as deep as some of us pursue for HT, Organ and Electronic music (ie 10-16Hz)?
Irrelevant in a discussion of speaker stands for standmount speakers.

And yes I am well aware that my pro sound mention is not 100% transferable to home audio, but the real difference is not that their world is uncaring about speaker vibrations: the real difference is that their world is full of trained engineers making purchase and setup decisions, who are slightly less susceptible to internet banter and comments starting with "an argument could be made", or product 'white papers' found somewhere on the internet, compared to home audio enthusiasts telling one another what is what. They just know what actually happens wrt vibration: eg if that suspended event speaker was moving back and forth freely with the (vast) sonic energy going through it, it could lose up to 6 dB of output, requiring a quadrupling of amplification power (and onsite generator output) to meet the SPL targets for the event. Not a trivial matter.

cheers
 

HiFidFan

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Paul's having a rough week
 
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