How Should Speakers be Stabilised?

[Phelonious Ponk]

It sounds like you don't appreciate what Blu-Tack really is

On the contrary, I do appreciate what it is, we're just not understanding each other well. Allow me to quote my own last post:

The concrete slab/blu tack? That's isolation from the surface, not coupling to it,

Transferring the vibration from a speaker cabinet to a wooden desktop, or a suspended hardwood floor, is exactly the opposite - coupling, extending that vibration to something over which your system has no control. I can sit my monitors directly on my desk and immediately hear and feel that coupling. What you're doing with the Blu-Tack and the concrete block is the opposite, it is de-coupling - isolating the speaker cabinet from the much more vulnerable surface of the desk or wood floor. Suspending that speaker cabinet, coupled to and vibriating absolutely nothing but the air around it would be ideal, and what I'm doing now is much closer to than even than the Blu-Tack to the safe with marble slabs on top of the speakers. That's why I won't bother with your experiment; I've been there, done that and moved on to the next step. You should try it.

Tim

 

[fas42]

what I'm doing now is much closer to than even than the Blu-Tack to the safe with marble slabs on top of the speakers. That's why I won't bother with your experiment; I've been there, done that and moved on to the next step. You should try it.

Tim

So you're saying you have actually tried Blu-Tack'ng to a very solid surface at some stage?

By the way, suspending the cabinet like that is most certainly vibrating something other than just the air. The energy transferred to the speaker carcase when the cones are working hard has to go somewhere, so the whole box is merrily vibrating in sympathy to the cone movement, adding a nice little chorus to the playback sound.

And yes, I have heard many setups like how you describe, and they sound bloody awful when you up the volume a bit ...

Frank

 

[NorthStar]

I also like big & heavy marble slabs on top of my subwoofers. ...Stabilize too.

Frank, you're right, you don't want to put heavy magnetic metal (iron, steel, ...) slabs there;
it will affect the Subwoofer's magnet(s), which ain't good at all.
The same is true for your loudspeakers (midrange driver or tweeter).

Cheers,
Bob

 

[fas42]

Frank, you're right, you don't want to put heavy magnetic metal (iron, steel, ...) slabs there;
it will affect the Subwoofer's magnet(s), which ain't good at all.
The same is true for your loudspeakers (midrange driver or tweeter).

Cheers,
Bob

Yes, there is something interesting going on with large pieces of iron based metals being near audio gear. My friend's CD player was sounding really dead and flat, and it didn't make sense because the earlier time it had been quite musical. All the usual suspects were OK, but finally noticed big lumps of steel, barbell weights, on top of its case (player was low down inside a cabinet). "What's this?" I said. His reply was that he thought it should help stabilise the player. "Let's get rid of them!" and lo and behold, the CD sound came back on song!!

Now, all sort of explanations can be put forward as to what was going on, but it certainly had a huge impact, in a negative way ...

Frank

 

[NorthStar]

It is simply the interaction between various metals and electronic circuits.
Chemistry! ...Biophysical properties...

That's why marbles, rocks, wood, rubber, are all safe materials with electrical stuff.

* I play guitars, electric among several, and I use plastic picks, even some wood ones and marble ones.
But no metal picks in my arsenal.
...And I don't wear watches or metal bracelets, or cheap rings (only fine gold or silver or diamonds) when I play the electric guitar.

 

[fas42]

Biophysical properties...

????

Hmmmmmm, he says, scratching his messy beard ...

Frank

 

[NorthStar]

I got the intended reaction!

See what I mean by the type of interaction that won't work good...
Metals and electricity (electronics) is the same; some combinations work best, others simply don't.

 

[Phelonious Ponk]

So you're saying you have actually tried Blu-Tack'ng to a very solid surface at some stage?

By the way, suspending the cabinet like that is most certainly vibrating something other than just the air. The energy transferred to the speaker carcase when the cones are working hard has to go somewhere, so the whole box is merrily vibrating in sympathy to the cone movement, adding a nice little chorus to the playback sound.

And yes, I have heard many setups like how you describe, and they sound bloody awful when you up the volume a bit ...

Frank

Blu tack in particular, no. rubber mats, concrete slabs, top weight, big rubber feet, little bitty spikes, shot-filled stands, unfilled stands, solid concrete column stands, wall mounts, huge, heavy wall shelves (made from doorway footers).......the list goes on. I went through a period in which I believed in speaker loading the way you believe in magic soldering irons. I tried many, many things. I concluded that I got the best results from good, rigid cabinet construction (even went into one set of cabinets and added bracing) and isolating the speakers from the surfaces they were sitting on rather than glueing them to them. YMMV. But really, Frank, everything you're suggesting, except for top-weighting the cabinets, will aim at the same result as isolation. It just won't be as effective.

Tim

 

[microstrip]

It sounds like you don't appreciate what Blu-Tack really is (...)
Frank

Frank,

I prefer UHU yellow tac, it does not stain, looks nicer and sounds much better!

http://www.shamrockcraft.com.au/UHU3952/UHU-YELLOW-TAC-80-PC_or_PKT/pd.php

 

[NorthStar]

I use Pink-Tack meself; between my shelves, behind my posters, my pictures, and everywhere...

Stops all type of room's vibrations, and gives a touch of 'Pink' to my highs.

But Blue is also a good 'mood', in particular with Blues.

 

[fas42]

Blu tack in particular, no. rubber mats, concrete slabs, top weight, big rubber feet, little bitty spikes, shot-filled stands, unfilled stands, solid concrete column stands, wall mounts, huge, heavy wall shelves (made from doorway footers).......the list goes on. I went through a period in which I believed in speaker loading the way you believe in magic soldering irons. I tried many, many things. I concluded that I got the best results from good, rigid cabinet construction (even went into one set of cabinets and added bracing) and isolating the speakers from the surfaces they were sitting on rather than glueing them to them. YMMV. But really, Frank, everything you're suggesting, except for top-weighting the cabinets, will aim at the same result as isolation. It just won't be as effective.

Tim

I'm pleased that you went through the heavy tweaking phase, but I feel you missed a key step: all the rubbery things are just that: springy, and minimal damping. That's why car suspensions use BOTH springs and shock absorbers, we've all driven past cars with shot shockers; the wheel is doing a merry dance bearing little relationship to the road, and giving a passengers a nervous time. That's what happens if you only use springy material, it MUST also include a damping mechanism somewhere for there to be a proper solution. Proper viscoelastics are "magical" materials that do both ...

But, and a very big but, if you get the speaker stabilised properly you can open a Pandora's box. All of a sudden you hear exactly where the system is going wrong, all sorts of nasty distortion become very obvious, so now you can go two ways: fix up the now apparent further problems, or go back to sloppy speaker mounting, which disguises the problems ...

Frank

 

[fas42]

Frank,

I prefer UHU yellow tac, it does not stain, looks nicer and sounds much better!

http://www.shamrockcraft.com.au/UHU3952/UHU-YELLOW-TAC-80-PC_or_PKT/pd.php

Now that's interesting! When you say better sounding, in what way precisely may I ask?

We won't worry about all the colours of the rainbow yet, Bob, unless you're after full spectrum sound ...

Frank

 

[Phelonious Ponk]

I'm pleased that you went through the heavy tweaking phase, but I feel you missed a key step:

And I think you missed a key point; everything you've talked about since the beginning of this thread, except for the dubious - at least for decently constructed cabinets - habit of placing heavy objects on top of your speakers, is about isolation. Blu Tack, concrete, rubber baby buggy bumpers...the entire OCD exercise is about isolation, ie; stopping the vibration of the speaker cabinet from radiating into the floor, the stand, the desk or table top, etc. A noble goal, the effect of which is subtle beyond description for all but someone like me who literally has has his speakers sitting up on top of a big resonating wooden platform, but purposeful nonetheless. Isolation, Frank. Can we say it together? I-so-la-ion. And yet, when I tell you that what I have done is literally float the speakers over the desk, completely uncoupling them from that surface, completely isolating them, you keep arguing. You ask if I wouldn't like to blu tack them directly to the surface of said raised and resonating wooden platform. Do you think that, somehow, four globs of blu tak might actually isolate more effectively than not touching the damn desk at all?

You puzzle me, Frank. I can't tell if you're deliberately being annoying, to amuse yourself, or if you don't even understand your own arguments. But it pretty much has to be one of the two.

Tim

 

[fas42]

Do you think that, somehow, four globs of blu tak might actually isolate more effectively than not touching the damn desk at all?

You puzzle me, Frank. I can't tell if you're deliberately being annoying, to amuse yourself, or if you don't even understand your own arguments. But it pretty much has to be one of the two.

Tim

We are at cross purposes here, Tim. If you don't understand, or don't want to, the usefulness of concepts like constrained layer damping -- one of the important ways that innovative speaker manufacturers like JBL use the phenomenon of viscoelasticity to kill vibration -- in terms of not simply isolating, but actually getting rid of vibration, by turning it into heat, then we can't proceed further ...

Frank

 

[Phelonious Ponk]

I understand very well the difference between what JBL is doing with damping in speaker design and what you're doing with concrete blocks and gobs of blu goo, Frank, and yes, we are done here.

Tim

 

[NorthStar]

Now that's interesting! When you say better sounding, in what way precisely may I ask?

We won't worry about all the colours of the rainbow yet, Bob, unless you're after full spectrum sound ...

Frank

Touche Frank!

 

[NorthStar]

By the way, can someone splain to me what coupling is good for, and also de-coupling,
and isolation as well?

Where and when one becomes critical?

And is there any weight to stabilization? I mean is weight help to stabilize your speakers?
...Of course it does.

Thank you.

 

[fas42]

By the way, can someone splain to me what coupling is good for, and also de-coupling,
and isolation as well?

Where and when one becomes critical?

And is there any weight to stabilization? I mean is weight help to stabilize your speakers?
...Of course it does.

Thank you.

A few points to get us going. First of all, vibration in anything but the driver cone or equivalent is bad, because you can guarantee that that vibration of the flat surfaces of the speaker or frame is not going to be beneficial to the sound. If you're very lucky they may harmonise with the sound, but you would have to be fortunate.

Now I mentioned in an earlier post that the speaker box is going to be shaken by the cone doing its thing; it has to because of old Newton's laws, for every action there is a reaction and all that sort of thing. The manufacturer may help if he's really nice by putting viscoelastic materials in the construction, the CLD, constrained layer damping I just mentioned. Typically in the sides, two layers of hard material with viscoelastic inbetween: the inner surface wants to rattle, so it pushes and pulls on the viscoelastic which works exactly like the shockers on the car, turns the energy into heat. So, inner surface rattles, next layer damps by getting warm, and the outside hopefully has minimal rattling.

Isolation works on the vain hope that if you don't have the vibrating surfaces or edges touching anything then the rattling will go away all by itself. Well, unfortunately there is no way to have a speaker not touching anything unless you have some magic anti-gravity device available, because it has to remain in place in the room. Even if you use ropes suspending the speaker in midair, the ropes have to hang from somewhere, and guess what: the vibrations of the speaker go up the rope and pull the mounting bolts in the ceiling up and down: your ceiling area becomes a panel speaker. Of course, if you want to go extremes, you could punch a hole in the ceiling and roof, build a gantry structure on the ground in the garden, and dangle a rope down through the hole. You're getting pretty close to isolation now!

So isolation in a typical situation is a myth: the speaker has to touch something to stop from falling down to the centre of the earth, and whatever it touches will vibrate, and on it goes. If you try putting it on a very rubbery thing of some sort that will stop what's underneath from rattling too much but what will happen then is the rubbery thing combined with the speaker will happily bounce ferociously and heat up the air around the speaker by its movement: this dissipates the energy but doesn't do much for the sound.

There is a whole science about handling vibration, it becomes quite messy and mathematical, companies make a lot of money trying to sort it out for customers, and a key technique is to turn the rattling into heat. Sometimes a solution may be found by a type of isolation, but the downside is that the thing that is moving could have little means to get rid of the vibrational energy and the device may end up shaking itself to bits.

Weight is good because it slows down the rate of vibration, the speaker box, not the drivers, goes from being a tweeter to a woofer! It's still vibrating, but the frequency is now nice and low, far less irritating and the energy has a better chance of transferring to what the box is touching. Again, there is a whole complicated science about all this.

And so endeth the lesson for the day ...

Frank

 

[NorthStar]

Good stuff Frankie, easy enough to understand in common mortal language.

 

[garylkoh]

I've been avoiding this thread because I'm just way too busy right now, but there is just way too much misinformation here for me not to weigh in, lest readers get led astray. We have to examine everything in the context of the loudspeaker and cannot just take vibration on its own.

Viscoelastics are materials that exhibit both viscous and elastic properties when undergoing deformation. The viscous property gives the material a strain rate that is time dependent. Different viscoelastic materials have a different strain rates. Blu-tack has a very LOW strain rate, which means that the viscosity is very high - it takes a long time before it departs its viscous properties and absorbs extremely low frequencies (with a "blob" far, far less than 1Hz). Sorbothane (the usual "audiophile" example, though) has a high strain rate, and hence loses viscosity very quickly - which is why is it good at absorbing higher frequencies.

However, you have to understand that the mechanical-to-heat conversion happens INSIDE the material. Sitting a loudspeaker on a viscoelastic material transfers some of the vibrations from the loudspeaker to the material depending on how well the loudspeaker is coupled to the viscoelastic material and those vibrations that are transmitted to the material are absorbed (or dissipated as heat). This protects the surface on which the viscoelastic material sits - which is why you use these materials as a vibration shield.

With ANY viscoelastic material, there is a pass-band beyond which it will couple. For example, a 20lb loudspeaker on three 2-inch sorbothane pucks may decouple at say 60Hz and above. On four pucks may decouple at say 30Hz and above. But de-coupling the speaker also makes it free to vibrate at those frequencies. Until you couple the vibration to the sorbothane, the sorbothane does not dissipate the energy of the vibration as heat. (Then, to solve all these vibrations, you have various vibration-controlling devices that you stick on or place on top of loudspeakers.)

At the frequencies we are talking about in damping a loudspeaker, blu-tack is a coupler, and sorbothane is a de-coupler. Even though both materials are viscoelastics. Although, if you use sufficient amounts of blu-tac, (I don't know how much, but much much more blu-tac than Tim's speakers cost) it could be a decoupler at audio frequencies.

Studying the technology (and there is a lot of good engineering in vibration control) of mounting diesel engines, jet engines, etc. will help, but cannot be relied on for audio. We are concerned with chaotic vibrations (there is no fixed period and magnitude) and not a constant vibration.

If you blu-tac a tiny monitor loudspeaker to a safe as Frank has suggested, you have mass-loaded the loudspeaker, and then it would depend on the design of the loudspeaker. I guarantee you that it will sound different. Whether it will sound better will depend on the loudspeaker. There is no universal solution.

If you blu-tac Tim's speaker to his desk (no matter how much blu-tac you use) you will add the sound of his desk to the loudspeaker. If you put a concrete slab between the blu-tack and the desk, then you are mass-loading the loudspeaker. Tim's way is much better if the speakers are well-designed and he likes the sound of his loudspeaker and not his desk.

I won't go into loudspeaker design because the thread topic asked about how loudspeakers should be stabilized (I still don't get how Frank can put spikes under a lot of weight and blu-tack between the speaker enclosure and what's under it - where does the blu-tack go, between the speaker and the spike?)

It will ALWAYS depend on the design of the loudspeaker. If Tim isolates his monitors with bricks and a rubber wedge (sort of a partial decoupling) and it sound best to him, that's probably best for his speaker. If your speaker sounds best spiked or blu-tacked to the floor, then that's probably the best for your floor and your speaker.

For floor-standing speakers, I generally find some de-coupling necessary in the US because of resonant floorboards. Most of the time, carpets are insufficient to dampen all vibrations in the floorboard unless the carpet has a foam or sorbothane backing. Blu-tac-ing your carpet to the floorboards will not help here. Coupling helps most of the time if the floor is non-resonant and solid.

For monitor loudspeakers, if you blu-tac the speaker to the stand, you will couple to the stand, which then mass-loads the speaker, and adds the sound of the stand to the loudspeaker. Which is why there are so many different designs of loudspeaker stands. If you spike the speaker to the stand, you also couple the speaker to the stand, but if you don't couple the speaker to the spike with blu-tac, then you have an interface between the bottom of the loudspeaker to the top of the stand that is coupled at some frequencies and decoupled at other frequencies depending on the material of the spike, and the material of the bottom of the speaker..... unless you blu-tac the spike to the loudspeaker.

If the speaker is really well-designed, I would de-couple the speaker and use a light-weight but rigid stand.

There are lots of coupling and de-coupling tweaks, and they all sound different. There is no universal solution like there is no universal loudspeaker or environment.