Do you need to spike mains if you have a subwoofer?

[pbarach]

I live in a wooden-frame home, my main speakers are KEF Q7's, and I have an M&K subwoofer; the crossover point I've chosen is 80 Hz. I use the subwoofer with movies as well as music. Is there any advantage to smoothness of frequency response in putting the supplied spikes on the KEF's, when low bass is being handled by the subwoofer?
Thanks for your thoughts on this matter...

 

[Sheep]

the spikes are to anchor the loudspeaker on carpet, and other "plush" floors. The spikes will damage hardwood and laminate flooring, so they are only for certain sitations. From what I have read, they are to help tighten up the low end response of a speaker. I don't know what frequency's they affect, but it couldn't hurt, plus it will add satbility.



sheep

 

[j_garcia]

Spikes keep resonance from being transferred to the floor, so whether you have a sub or not is irrelevant. They shouldn't change the response of the speaker, but they will keep the floor from vibrating along with the speaker. You can put a penny or something similar beneath the spike.

 

[WmAx]

Spikes keep resonance from being transferred to the floor, so whether you have a sub or not is irrelevant. They shouldn't change the response of the speaker, but they will keep the floor from vibrating along with the speaker. You can put a penny or something similar beneath the spike.

How does a spike "keep resonance from being trasnferred to the floor"? The principle function of a spike is to create a rigid coupling system.

If your floor happens to have a problematic[as in audible problems occuring when the stimulus of the speaker cabinet vibration is applied] resonance that co-incides with the speaker bandwidth, a rigid coupling will ensure that said resonance is excited maximally, as compared to a de-coupled mounting[using a suspension with a resonant frequency that is below the problematic resonant frequency].

-Chris

 

[j_garcia]

Contact area is minimized, thus reducing the amount of transmitted vibration vs placing the speaker directly on the floor. Obviously, not as well as using a dampening material, but it still provides a similar function.

 

[snickelfritz]

Spikes generally have nothing whatsoever to do with the sound of the speaker (aside from tilt angle adjustement in some designs), nor do they reduce resonance transmission to the floor, "tighten up the low end", or any other horse-puckey.
They are intended to provide a means for stabilizing and plumb/leveling speakers (towers especially) on plush carpet and uneven floors.

Wood/frame sub-floors might be energized by spikes at a different frequency than without the spikes, which some listeners might interpret as a positive change in the sound of the speaker.
It's really just the floor singing a different tune.

 

[WmAx]

Contact area is minimized, thus reducing the amount of transmitted vibration vs placing the speaker directly on the floor. Obviously, not as well as using a dampening material, but it still provides a similar function.

When you reduce contact area, the contact force per area increases, in the inverse proportion. The net effect = same. Example: 10 kg applied to 4 cm^2 contact area will have 2.5kg per cm^2. If you reduce contat area to 1cm^2, you end up with 10 kg per cm^2. To reduce the coupling with a smaller footprint of a spike vs. a larger foot, for example, you would need to be able to retain equal pressure per area as you decrease the contact area, instead of it[force] increasing proportionately as surface area is reduced.

-Chris

 

[j_garcia]

As snickle-whazit points out, the spikes will modify the frequencies at which the resonance is transmitted to the floor, though you are right, not eliminate it. (sorry, I wasn't clear) The amount of energy transmitted is not reduced, but how it is transmitted is modified. Certain frequencies may be increased, while others decreased, which may or may not be a good thing depending on the particular frequencies in question and whether or not resonance is actually a problem.

There is also a factor of cabinet resonance - decoupling means the cabinet loses some of its own resonance to the decoupling material, and some speakers rely on that resonance to achieve a particular sound. This will tend to show up in the mid to bass regions.

As I said before, response of the speaker itself is not really changed with a spike. Spikes maintain a solid connection with whatever the speaker is being coupled to, but there is definitely a modification of the transmission of sympathetic resonance at a given frequency to the floor (generally in the case of a wood floor). The only problem is pretty much no way to figure out what frequencies will be exaggerated or attenuated.

 

[WmAx]

As snickle-whazit points out, the spikes will modify the frequencies at which the resonance is transmitted to the floor, though you are right, not eliminate it. (sorry, I wasn't clear)

Thank you for the clarification.

There is also a factor of cabinet resonance - decoupling means the cabinet loses some of its own resonance, and some speakers rely on that resonance to achieve a particular sound.

If a cabinet's panel resonance(s) is(are) appreciably changed in any way due to a rigidly coupled spike feet system, versus say a decoupled suspension[for illustrative purposes of extremes], then the cabinet would have to be extremely thin and [extraordinarly] poorly designed, with the main resonant points concentrated in the proximity of the foot mounting contact area.

Spikes maintain a solid connection with whatever the speaker is being coupled to, but there is definitely a modification of the transmission of sympathetic resonance at a given frequency to the floor (generally in the case of a wood floor). The only problem is pretty much no way to figure out what frequencies will be exaggerated or attenuated.

It is difficult to predict what will happen in a specific circumstance, due to the large number of variables that are unknown. Given sufficient data concerning the specific situation, of course, it's predictable.

In my case [and I suspect many people have this issue] only de-coupling [though it will take more than rubber feet to decouple the low frequencies that will be the main problem] was desirable. My listening room has wooden joiced floors that resonate excessively when full range speakers are directly coupled to the floor. The floor would slighlty vibrate at certain frequencies[this is annoying to me] and it was percieved that bass sound quality was reduced[not quite as clear] when speakers were coupled. I use a suspension platform system with a resonant frequency below the problem resonance to alleviate most of the problem[some residual energy is still transmitted via air pressure].

-Chris

 

[j_garcia]

If a cabinet's panel resonance(s) is(are) appreciably changed in any way due to a rigidly coupled spike feet system, versus say a decoupled suspension[for illustrative purposes of extremes], then the cabinet would have to be extremely thin and [extraordinarly] poorly designed, with the main resonant points concentrated in the proximity of the foot mounting contact area.

Well, it's definitely much more likely to show up in a poorly designed cabinet vs a sturdy one. I'd say most mass market (big name store type) speakers these days have pretty decent cabinets. Athena was the first to surprise me. The bookshelf speakers are very light for their size (to me anyway) and they sounded as though the wood was quite thin, yet the midrange is clear and cabinet resonance seems pretty low. One of my speakers weighs more than a pair of B1s in their packaging, yet their design seems to be capable of decent midrange, though bass is a tad sloppy (not bad at all for their current price tag). I always tap on the side of a speaker to hear the cabinet, yet I never really understood how much of a factor it could be until I actually listened to a decent set of speakers that were well built and I didn't hear the cabinets.

 

[Bryguy]

I'm definitely no engineer or physics guru but I have to agree with snicklefritz that spikes are basically snake oil except for anchoring a speaker onto carpet. My opinion is they keep the speaker from moving around the carpet due to resonance frequencies / vibrations (kind of like an off balance washing machine moving about).

I am currently using spikes myself but would like slightly larger ones so they can raise my speakers a little bit more so if my dog goes on the carpet it won't soak into the speaker.

Bryguy

 

[mtrycrafts]

I live in a wooden-frame home, my main speakers are KEF Q7's, and I have an M&K subwoofer; the crossover point I've chosen is 80 Hz. I use the subwoofer with movies as well as music. Is there any advantage to smoothness of frequency response in putting the supplied spikes on the KEF's, when low bass is being handled by the subwoofer?
Thanks for your thoughts on this matter...

Other than as stated above about carpets, not to worry. Forget it.

 

[WebImages]

I just installed my speakers (B&W 704s) on a wooden floor. The dealer told me that I would need to use spikes with Skeets (little concrete pads to keep the spikes off the floor).

When unpacking the speakers I found that they were delivered with both spikes and with 'rubber' feet that could be used on a wooden floor - - Long story short I used the 'rubber' feet and find the speakers perform well.

Who is right? Should I have purchased the Skeets?

Thanks

JohnJ

 

[pbarach]

KEF's response to my question about spiking Q7's

"There many are benefits to coupling the Q7's speakers energy to the
floor through the use of spikes because the spikes absorb resonate
energy that would normally be passed into the floor , and it also makes
the sound reproduction of the speakers more stable . I know that in
your case you may not benefit from this as much because of the
crossover frequencies that your playing your speakers at. Have a great day."

 

[Sheep]

don't take it from me.

This is a quote from Clint regarding the velodyne deco sub.

"The Deco subwoofer would benefit from a set of spikes to better anchor it to the floor - this shouldn't affect the visual design at all and would improve tactile response. I felt as though a lot of the resonant energy put off by the sub was being lost or dampened by the carpet it was sitting on. To see if this made a difference I added about 35 pounds to the top of the Deco sub and did indeed notice the low-end extension tighten up a bit"

Hokus pokus? I don't think so.....


sheep

 

[WmAx]

.... because the spikes absorb resonate
energy that would normally be passed into the floor ...

This 'customer service person' at KEF clearly does not know what they are talking about.

-Chris

 

[WmAx]

This is a quote from Clint regarding the velodyne deco sub.

"The Deco subwoofer would benefit from a set of spikes to better anchor it to the floor - this shouldn't affect the visual design at all and would improve tactile response. I felt as though a lot of the resonant energy put off by the sub was being lost or dampened by the carpet it was sitting on. To see if this made a difference I added about 35 pounds to the top of the Deco sub and did indeed notice the low-end extension tighten up a bit"

Hokus pokus? I don't think so.....


sheep

Likely, the reviewer experienced the effects of resonanting the floor structure[when using additional mass to couple through the carpet/padding better] ,or alternatively, imagined the difference.

-Chris

 

[Sheep]

Well, why don't you ask clint yourself?



sheep

 

[mtrycrafts]

When unpacking the speakers I found that they were delivered with both spikes and with 'rubber' feet that could be used on a wooden floor - - Long story short I used the 'rubber' feet and find the speakers perform well.

Who is right? Should I have purchased the Skeets?

Thanks

JohnJ

You are right. Use what came in the box, not the stores as they have a financial motive

 

[mtrycrafts]

This is a quote from Clint regarding the velodyne deco sub.

"The Deco subwoofer would benefit from a set of spikes to better anchor it to the floor - this shouldn't affect the visual design at all and would improve tactile response. I felt as though a lot of the resonant energy put off by the sub was being lost or dampened by the carpet it was sitting on. To see if this made a difference I added about 35 pounds to the top of the Deco sub and did indeed notice the low-end extension tighten up a bit"

Hokus pokus? I don't think so.....


sheep

Maybe clint should have this measured as well as he did with the sub break in experiments.
I think he was affected by bias? After all, it was a subjective analysis, bias not removed He is not immune from it, is he? I want to see his certified immunity card