Speaker Spikes - do the shake test


Everyone by now knows that speaker spikes improve the sound. The theory is that the tweeter excursion is so short, that any speaker cabinet front to back movement creates Doppler / intermodulation distortion. That movement can exceeed, by many times, the excursion of the tweeter. So, the effect is most pronounced up top and then towards the bottom most frequencies. Or so they say.

I have some C4 series II speakers that come with four “spikes” in the plinths. But, the people in Denmark seem to think we all have hardwood floors. The so-called spikes are dull “lugs" that really are meant to sit into four small aluminum floor bot dots, for any better term for them. Many have speakers on carpet, and the so-called spikes sitting on those four round aluminum discs still are pretty wobbly on carpet.

Last week, I pulled all eight of the spikes (not nearly sharp enough, with a 30 degree rounded tip, to be called a spike) and had the guys in the machine shop at work lath them to 60-degree POINTS!

OK, re-installed and speakers leveled (four point level is a pain). WOW, now they are stable as a rock when you push and tug on them. What was NOT expected, was that the BASS response is significantly better. Not that bass is easy to do, but the contribution to the C4’s bass that spikes that are now planted into the concrete floor and under the carpet is amazing. The bass can now place a black dot on a white background as needed. Everything isn’t a shade of gray in the bass. I always felt that the C4’s weakness was bass definition, but the weakness is that Dynaudio doesn’t supply two sets of spikes, those for hard surfaces and those for carpet. That’s too bad, as the supplied spikes don’t cut it on carpet. My spikes are now good enough to pierce down below the carpet and rest on the concrete. But, real spikes should be like half-inch ten-penny nails that don’t chew-up the carper as much as my 60-degree spikes. But, I can’t find this spikes for the C4’s.

If you are like me and haven’t given your speakers the shake test, go do it! If they wobble around any at all see what you can do to fix it. The rewards are well worth as close to free upgrade as I’ve ever done. Don’t think for a second that it seems, “good enough”. If they move around, it isn’t.
rower30
OK,

I think we have TWO evolutionary paths, speakers placed on "soft" floors, and those placed on "hard" floors. A soft floor being a typical floor is a house supported with joists. A hard floor being (in my case) ten inches of concrete.

I would certainly agree that as different as these surfaces are, the method to tune the sound would be, too. The agruments probably have to be very specific as to what general floor type is being addressed.

I do hear this, big tall wobbly C4's like sharp steel SPIKES on concrete to tighten-up the sound.

My point of the post is to EXPERIMENT and not accept what's thrown your way. There is no harm in going back to your original set-up if you don't like what you hear.
I have a so-called "soft" floor, one atop joists with a basement beneath. The floor is carpeted. I used to have sharp spikes in all four corners under my Unity Audio Sig 1's. Just thought one day "Let's try Vibrapods." Removed the spikes, placed granite floor tiles (12"x12") under the speakers with the Vibrapods between speaker and tile. Huge difference!! Images were clearer, much better bass, maybe because there was no wobble on the spikes, I can't really say, but the difference was not subtle.
I like to think speaker manufacturers, especially those with a proven track record, know what they are doing when they assemble a speaker system and provide specific accessories.
If you think about what is going on, the effects of a neutral cabinet motion are critical to getting the best from your speakers.

For example, look at a high-end scan speak tweeter, the one's I call the cone-heads. That big spike in the middle of the tweeter is designed to make sure the CENTER of the tweeter move about when the EDGES of the tweeter, where the voice coil is attached, moves. And, to beam the energy more sideways so it's arrival time is more room "reflections than direct, improving resolution. A mechanical device is not infinitely stiff, so the middle of a round object, with the "push" coming from the edges will have a ripple effect towards the tweeter (in this case) center. If the middle of the tweeter is mechanically "soft" it will actually lag behind and dimple inward compared to the edges and add significant Doppler / intermodulation distortion.

Some tweeters use central phase plugs to damp this out, but all of them are aware of the shortcomings of a too soft structure and manage it somehow...apparent or not. The stiffer a structure is however, the harder it is to damp once it gets going.

Look at the distance a tweeter moves...Well, you do it, I can't see that well anymore. Its motion is virtually invisible to the naked eye. Want crisper sharper imaging? Add a bunch of cabinet resonance to the speaker front panel that is orders of magnitude worse than the tweeters full excursion. The tweeter doesn't stand a change to be at it's best.

Bass is more controlled by the cabinet itself as the wavelength / excursions of the driver are at the opposite end of the spectrum, much longer than the cabinet resonance. Lets hope so anyway. Still important, but not the pinnacle of perfection the mids and tweeter demand.

Look at speakers as they get larger, and harder to damp. A HUGE part of the price is stopping the darn cabinet from moving. Big speakers carry a lot of extra "loose" baggage that has to be managed, at a big cost. Internal braces and exotic shapes all to simply get the drivers to stand still. When the braces are added, it steal cabinet volume from the drivers and the cycle feeds on itself as the cabinet is made bigger to account for the lost internal volume the braces removed. OK, use carbon fiber and it feeds on your bank account. You pay all that money, and then let the speaker wobble all over the floor? Want to know why so many fantastic smaller speakers exist? Well, now you know...the cabinet is order of magnitude stiffer as they get smaller all things being the same in the design. A panel half as long is four times stiffer.

But, once you select a speaker what ever it takes to keep that front panel from moving back and fourth (the speaker cabinet itself is a done deal) is as important as any component in your system, probably in the top three (and it's actually pretty cheap to optimize).
My experience is quite similar to Mrmitch.

I have a suspended floor. My best results with my monitors is on Vibrapods. This decoupling without much absorption retains the microdynamic energy of the music and results in more presence and better bass definition and heft. Amazingly clarity did not suffer like it did on blue tack. Brass cones gave the most clarity.

Vibrapods on my floorstanders resulted in sloppy bass. I compromised by using cork/rubber isolpads which gave the best balance of warmth, microdynamics and clarity.
The factory spikes made the floorstanders rather cold sounding in comparison.