Tower speakers on hardwood floors: spikes on discs/coins? Sorbothane/silicone pads? Springs?

[Tachyon88]

From what I gather it seems to not matter much for a regular concrete floor, but what about tower speakers and subwoofer for a pier and beam type house ?

 

[goat76]

@SteveC I was Linn guy too and I could ear differences on everything, spikes up or down, cables, different TT support, name it, I am still a Linn guy, because I still own my Linn system, and I still like it very much, but not for the same reasons as 20 years ago.

Speaking of Linn…

I have used Linn Skeets under my speakers for many years. They are not just good for protecting the floor, they also make it easier to slide the speakers on the floor while optimizing the placement. They are made of a hard material (volfram), so they are fairly heavy for their size.

 

[Cote Dazur]

Those have been doing the job under my speakers for years as a replacement of the pikes.

 

[MAB]

From what I gather it seems to not matter much for a regular concrete floor, but what about tower speakers and subwoofer for a pier and beam type house ?

My experience is if you have wood floors, that is what you have. You can try to decouple the resonances with all sorts of methods. But speaker placement in the room is going to dominate the bass response and how the floor behaves. And if the floor is bouncing around it's because there is a bass sound-field in the room and the floor is one of the room boundaries. The idea that the loudspeaker chassis is the main driver of any resonances in the floors is just not correct. It plays a small role, but if you have a resonant floor and you have a speaker with bass energy at the floor's resonance it will resonate because the floor is acting like an elastic boundary rather than a solid boundary.

Here is a subwoofer in a room, the floors are 100 year old hardwood, I would characterize them as less resonant than most old floors, for instance they don't ring like tympani, but they are not tiled concrete either... I have a Seas L26 subwoofer, no EQ. I measured the sub on 2mm felt floor-pads, then again on elastomeric speaker dampers that are 2cm tall, then again on 2cm multi-density spikes with little machined pockets to prevent floor damage. I made sure to keep the subwoofer in the same position between each setup, only the sub's height off the ground changed (2mm for the felt pads, 2cm for both the spikes and elastomeric feet). The mic position did not change.

There is a tiny change between the felt pads (black dotted line) and the elastomeric feet and the spikes (green and red lines) (+1dB at 300Hz, +0.5dB at 600 Hz, -0.5dB at 190Hz). But the difference between the elastomeric feet and the spikes is negligible.
Two conclusions:

1. The position of the speaker in the room matters, the composition / method of the speaker to floor coupling does not.
2. The room modes are 10dB!

Use feet that provide stable footing on the floor, don't damage, and make it easy to explore the large changes that occur when you move your speakers around, and be prepared to measure those changes since everything rooms are the sound in them are complicated. I don't use spikes, if I had a wall to wall carpet I would consider them if they helped stability.

 

[kifeep]

the difference between the elastomeric feet and the spikes is negligible.

Thank you for the graph. One claim made earlier in this thread is that any differences that may exist with different feet are most likely to manifest as distortion. Since you've already made the measurements, could you share distortion graphs so we can see if this is the case in your room?

 

[OldHvyMec]

Post 31, IF you add up all the little distortions, resonances, vibrations, and everything else that changes what you hear at what point does it
matter if you don't address them?

My point has always been the same, once you experience a properly dampened room that is decoupled vs one that isn't or at least treated,
you won't know what you're missing OR in many cases putting up with.

Nothing is worse than speakers spiked or coupled to any floor once you try one that isn't. The source used to be very vulnerable to vibration
and it never helped a valve-based system that I know of.

Everything we were ever taught as apprentice mechanics was the same. ALL components last longer and have fewer problems if you reduce
vibration. That includes glass, wiring, electronic components, chassis and especially the engine, transmission, and any drive train components.

Have you ever been in a car where the tires were out of balance, lost a drive shaft, or an engine that was misfiring or worse lost a
harmonic balancer? A diesel will last less than 100 hours after losing a balancer. They will break a crankshaft in half. I've had to replace
many crankshafts behind losing balancers.

I've seen some sub/bass systems back paneling nails out and the panels start humming. Decouple the sub/bass, use liquid nails, and reinstall
the panels. It's amazing the change it makes and you don't need to measure a thing to HEAR the change in the definition and clarity from
200hz > because of the vibration and out of time driver BELOW 200hz, The floor!

There is a reason for rumble filters with TT, CDs, Tapes, and some valve gear. It sounds better because they CUT the vibration/noise from reentering
via the source or valves rattling or worse making valves (systems) go underwater.

Springs, pods (bellows), air ride, accumulators (shocks), doinky mats, Sorbothane, low-pressure pneumatic tires, ceiling cable suspension with
spring/absorbers and combinations of any, and all WORK. BUT you have to listen NOT MEASURE. But you can if you must, why do you think
there are rumble filters? FOR RUMBLE! By adding decoupling to any platter/cart you are able to go deeper.

By balancing tires you are able to do what? GO FASTER and control the vehicle on the road. Leave OUT that part on a 64VW bug and see how fast
you wind up in a ditch vs keeping the tires on the road or as some people say keeping the rock in the groove on an LP.

The flat frequency response that most of us like is a STARTING point. A reference to go back to or measure against.

My personal speaker that I BUILD and have been building for 45+ years are tried and true to my liking AND they measure pretty flat.

None of that matters if the room isn't set up to accordant the type of speaker drivers I use. Sub/bass when coupled to any surface
(NOT bouncing off) add a huge driver that is out of time.

I dampen the room to a point and decouple to remove the adverse effect that a huge undampened driver can vary from song to song.

When a room is decoupled it's no different than STARTING with a (close too) flat frequency response from a speaker.

It's quite simply a reference point you don't have to manage from source to source or worse song to song. When your system can play all
venues (considering the recorded source) you truly have a complete reference system not just one that works on some songs, venues, or
source players, LIKE a turntable, a CD, or using a valve-based system.

Have people ever considered that a digital streamer might sound better because it is far less affected by vibration, to begin with?

This stuff is 101 first-year apprentice tech that has been used before Henry Fords' time. He didn't reinvent the wheel or argue with the FACTS
he just improved on what had been working since Fred a Wilma from the Flintstones. Round rocks vs round rubber tires. Vibration control
adds up collectively to make a huge difference.

Regards

 

[MAB]

Thank you for the graph. One claim made earlier in this thread is that any differences that may exist with different feet are most likely to manifest as distortion. Since you've already made the measurements, could you share distortion graphs so we can see if this is the case in your room?

I measure no differences between feet type:

These are tiny distortion differences between spikes, elastomeric feet, and felt pads. Nobody is going to hear these differences even if they are each due to the type of feet. In reality, the few differences are traffic down the hill from me, and my inability to swap feet and return a heavy sub to within millimeters for each measurement.

For a perspective on run to run repeatability, here are two control measurements taken from another location in the room. Each sweep was taken 30 seconds apart, absolutely no setup or mic changes:

The speaker-floor coupling thing is such a small order issue compared to room acoustics and speaker placement. If you have feet that allow easy setup and good stability, that matters. Making the feet out of spikes or balls or advanced sound absorbing stuff really plays no role in the sound, unless those feet change the position of the speaker or are so flawed the speaker is rattling around. For many people with thick carpet spikes work great. For people with hardwood floors who wonder what they might be missing with spikes, nothing. Thing is, lots of speakers have very nice feet that allow tilt and other fine tuning which will have an effect and can do good things like tame an overly hot on-axis treble by adding some tilt.

 

[MAB]

This raises a few interesting questions to my mind. I would appreciate any education on this.

1. The idea that coupling might result in distortion sounds plausible, and is certainly measurable. I wonder has anyone has published any measurements that address this?

2. If I understand correctly, harmonic distortion at, say, 80Hz would manifest as additional energy at 160, 240, etc. Would one expect to be able to see this in a typical frequency response graph? I imagine one would have to look at the distortion graph to correctly identify the cause of the bump, but there would still be a difference in the isolated vs non-isolated frequency response graphs, right?

3. This all made me think of a related question about directionality, I guess. The linked Ethan Winer article demonstrated that energizing a speaker didn't activate known resonances in the table, but if vibrational energy was present in the table, could/would this affect the speaker output? And if so, could isolation products possibly mitigate it? Or does that lack of transfer of energy to the table directly imply that the speaker is equally immune to influence from external energy?

Thanks.

The floor and all of the surfaces of the room, have a set of resonances. Each one is a different mode. If you excite one or more of these modes, they will resonate at whatever the characteristic frequency of that mode.

Any of these can be excited. Any of these modes will have resonances at other harmonics as you suggest, various multiples of the dimensions and elasticity of the floor, the relative magnitude hard to tell. They are are functions of the room dimensions and since we are talking about floors, the floor modeled as an elastic film:

Since your room is your speaker, the vibrations in the floor will be measurable.

 

[Chrispy]

Can't imagine using spikes on hardwood or something to alleviate such spikes instead of something more sensible. Way overthought it seems but when did that stop something from getting sold?

 

[Old_School_Brad]

Speaking of Linn…

I have used Linn Skeets under my speakers for many years. They are not just good for protecting the floor, they also make it easier to slide the speakers on the floor while optimizing the placement. They are made of a hard material (volfram), so they are fairly heavy for their size.

View attachment 395285

It seems like it's oxidizing on your floor.

 

[Chromatischism]

In my experience there is no best--it depends what you want. More rumble and impact (good for systems lacking it), couple them to the floor. Or a lighter, clearer sound (good when you have plenty of power and/or need to keep sound from transmitting to other rooms), isolate them with absorbing material.

 

[goat76]

It seems like it's oxidizing on your floor.

It looks like that, but the coloration is just from a green pencil I use to mark the speaker's positions on the floor. It can be erased.

 

[Chromatischism]

As bad as our hearing is in midrange frequencies

What? Since when? Midrange is our strongest area.

it is next to useless for quantifying bass.

Our hearing is very sensitive to changes in bass frequency, including changes in the balance of different bass tones occurring at once.

 

[Chromatischism]

original feet just to do a REW measurement. It was patently clear that the detail and clarity of the bass was improved when I switched to the Gaias. These are things that can't be measured

Anything and everything can be measured.

Now, I'm not saying that to doubt that you heard something different. You likely reduced the floor resonance, which results in the perception of less overall bass because it now lacks the physical, tactile component. And less is often focused on more and perceived as more detailed.

Riddle me this: how many times have you read an audio review and seen the words: "they don't produce much bass, but what is there is very well controlled"?

 

[goat76]

Thing is, lots of speakers have very nice feet that allow tilt and other fine tuning which will have an effect and can do good things like tame an overly hot on-axis treble by adding some tilt.

I use the spikes to tilt my speakers but not for any taming reasons.
The two spikes in the front are 12mm longer than the two in the back, so the mid-drivers (the acoustic axis for my speakers) are pointing straight at the ear level at the seating position. Even if it may seem like a small amount of tilt I found it made an audible difference, maybe because I'm sitting fairly close (2 meters) to my speakers. At much longer listening distances than that, the tilting may not be as audible when the ratio of direct sound is lower.

 

[tmuikku]

Some nuggets anyone can use to reason what might be good for their system:
Spikes couple to floor increasing system mass which ought to reduce vibration of the cabinet assuming rigid floor. Damping feet isolate from floor, which should reduce vibration coupling to the floor, perhaps dampens vibration of the speaker as well. Important in vibration dampers is their own resonating frequency, which needs to be lower than vibrations it is supposed to dampen, and the weight needs to be optimal for the particular dampener to allow max flex. Too light or too heavy, and they don't work optimally.

As bonus, try this quick fun test: put your speaker on laying position, drivers pointing up (or down) and notice if more vibration makes into the floor compared to upright position. Test your dampening feet effectivity in this orientation to see differences more clearly.

 

[Pareto Pragmatic]

As bonus, try this quick fun test: put your speaker on laying position, drivers pointing up (or down) and notice if more vibration makes into the floor compared to upright position. Test your dampening feet effectivity in this orientation to see differences more clearly.

That's a good idea.

I usually just compare REW sweeps to white noise captured by RTA. White noise should activate any resonances a lot more than the sweeps, and capture how resonances reinforce each other. Where the measurements track together, no issues.

As for fun, hitting my floor with a baseball bat was definitely a fun way to measure floor resonance.

 

[MAB]

Our hearing is very sensitive to changes in bass frequency, including changes in the balance of different bass tones occurring at once.

I was speaking specifically about using our ears as measuring devices, not as perception or prediction tools but as tools for quantifying sound.
Our hearing is not good at quantifying sound. As bad as it is at quantifying sound, it's worse at bass frequencies.

Yes we can perceive differences in tone as you suggest, that isn't quantification. This is:

Microphones are good at both detecting and quantifying sound.

 

[MAB]

Anything and everything can be measured.

Agree!

Now, I'm not saying that to doubt that you heard something different. You likely reduced the floor resonance, which results in the perception of less overall bass because it now lacks the physical, tactile component. And less is often focused on more and perceived as more detailed.

Also agree, changes in the floor's resonance definitely change the tactile experience.

That being said... I never know exactly what people change in their setup...
Often people change speaker position, either inadvertently or by not realizing this needs to be controlled for to make valid observations. Especially if a speaker sits at one of the nodal points of a room where small changes in position cause large swings in SPL.
Usually people just fool themselves since our ears aren't good at measuring / quantifying.
The idea that the speaker/floor interface is a big deal in sound reproduction is odd and incorrect, very little energy is dissipated from the speaker's chassis through the feet to the floor. The majority comes from the floor coupling to the acoustic energy in the room.

And thus the type of feet should be chosen for stability, movability, and adjustability of position.

 

[kifeep]

I measure no differences between feet type:

Thank you for your responses, especially the distortion graphs. My earlier questions were mostly about whether the posited distortion issues could be gleaned from frequency response since no one had posted distortion data yet. (I had also seen a number of accelerometer graphs on other threads, which I found similarly difficult to infer the implications of.)

To me, this is the best and most direct support of the position that feet have little-to-no effect and I appreciate your posting it.