Vibrations, audio components, and sound

PeterA

Active Member
Dec 7, 2011
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North Shore of Boston
#1
I would like to learn more about the different types of vibrations and the deleterious effects they have on our audio components. I have observed the effectiveness of my attempts to address certain vibrations in my own system, but I am sure I have only just begun to scratch the surface of this topic. Here are six questions that can get the discussion started and perhaps begin to clarify the issues involved:

1. What are the different types of vibrations?
2. What causes these vibrations?
3. What components are most susceptible to these vibrations?
4. What is the best way to manage these vibrations?
5. Can we measure the distortions caused by these vibrations?
6. Can we determine through science how effective our solutions to these vibrations really are?
 

BlueFox

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Nov 8, 2013
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Silicon Valley
#2
This is a good topic and question. My experience appears to support the idea that vibration control results in better audio, and between the 500 pound solid maple rack, along with brass footers, I have spent a few dollars trying to eliminate vibration distortion. So it would be interesting to see data supporting that experience.

I would guess everything is susceptible to vibrations to some degree or another, but I would guess a turntable would be the most susceptible, with tubes coming in second.
 
Jul 25, 2012
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NY
#3
Someone could place a solid state component on top of a subwoofer and you would never know it unless you looked.

Turntables are another story.
 
Jul 1, 2010
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#4
Active studio monitors, even some very expensive ones, are built with amps, and sometimes even preamps and DACs, inside the speaker cabinets, with no obvious problems resulting. So I too, would like to see data supporting this common audiophile belief.

Tim
 

PeterA

Active Member
Dec 7, 2011
4,881
12
38
North Shore of Boston
#5
Active studio monitors, even some very expensive ones, are built with amps, and sometimes even preamps and DACs, inside the speaker cabinets, with no obvious problems resulting. So I too, would like to see data supporting this common audiophile belief.

Tim
Yes, that's a good example, Tim, and makes one wonder just how important the vibration issues are. Crossovers, with sensitive connections and electronics are also inside most speakers. Some manufacturers make the effort to try to isolate these electronic components from the air borne and structural vibrations that surely occur inside these speaker cabinets. Some of the pressures must be enormous, especially with sealed cabinets. I think that often the amps, crossovers, etc. are separated in their own enclosures and/or mounted on shock absorbers.
 
Jul 1, 2010
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#6
Yes, that's a good example, Tim, and makes one wonder just how important the vibration issues are. Crossovers, with sensitive connections and electronics are also inside most speakers. Some manufacturers make the effort to try to isolate these electronic components from the air borne and structural vibrations that surely occur inside these speaker cabinets. Some of the pressures must be enormous, especially with sealed cabinets. I think that often the amps, crossovers, etc. are separated in their own enclosures and/or mounted on shock absorbers.
I'm sure the manufacturers of actives take steps to isolate anything that...well, no, I'm not really sure of that at all. Most of the manufacturers of active speakers are in the pro audio world and don't share many common audiophile beliefs. But most actives are built with amps on a steel backplate, screwed to the cabinets that are designed to be inert, so I can't imagine there's much to worry about.

Tim
 

DaveC

[Industry Expert]
Nov 16, 2014
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#7
I incorporate mechanical damping in the components I build. Silicon, felt and viscoelastic damping material are used to control vibration in PCBs and the parts mounted to them, transformers are placed on a thick pad of felt, and capacitors that are secured with cap clamps have felt or cotton cloth between the cap and the clamp. A combination of hardwood and metal is used for both aesthetics and resonance control.

Even large manufacturers like Sony have put a lot of thought into their chassis and footer designs. From Steven Stone's TAS Article:

"Unlike many digital products, where the chassis is merely a big metal box, the HPS-Z1Es uses “Frame Beam Chassis” construction, which Sony has used on all its ES-level products in the past. The HP-Z1ES’s base is composed of two metal plates of different thicknesses that support the main chassis. There are two additional base plates under each power transformer. Along with these metal plates, Sony employs structural beams than run crosswise to reinforce the overall rigidity and improve resonance control."

http://www.theabsolutesound.com/articles/sony-hap-z1es-hdd-audio-player/

While it's true many good sounding systems and components don't pay much attention to this issue that doesn't mean there are no improvements to be had if they did. And for many that's part of the hobby, improving everything possible.
 

PeterA

Active Member
Dec 7, 2011
4,881
12
38
North Shore of Boston
#8
1. What are the different types of vibrations?
2. What causes these vibrations?
3. What components are most susceptible to these vibrations?
4. What is the best way to manage these vibrations?
5. Can we measure the distortions caused by these vibrations?
6. Can we determine through science how effective our solutions to these vibrations really are?
I don't have much of a technical background, but I will try to answer some of these questions. Please correct any mistaken or incorrect information.

1. Types of Vibrations:
A. Air borne vibrations.
B. Floor borne vibrations.
C. Internal mechanical vibrations.

2. Causes of Vibrations:
A. Air borne vibrations - primarily speaker output, sound wave pressure
B. Floor borne vibrations - earth/ground structural movement, foot falls, movement over springy floors.
C. Internal mechanical vibrations - speaker drivers, current running through wires, transformer hum, tube filament movement

3. Components, in order, most susceptible to vibrations:
Turntables, speakers, tube electronics, SS electronics, cables

4. Vibrations management solutions:
A. Air borne - isolation in a different room, lower profile/surface area, mass loading
B. Floor borne - isolation from source: rubber, air bladder, active servo, different room location
C. Internal mechanical - damping, isolation, mass loading, mechanical energy drainage path

5. Can we measure the distortions? Probably, though I have no idea how.

6. Can science help us? Certainly, but I don't see much discussion about specific solutions.

One solution that I use is a multi-tiered approach. My turntable has a thin profile to address airborne vibrations. It has a mechanical separation between the motor and platter/armboard. It has a soft, scrolled platter surface for better contact and vibration dissipation with the vinyl. It has a mass loaded and energy drainage path for mechanical vibrations to exit the armboard and the entire system via steel ball bearing footers. These rest on a floating 280 lbs steel mass above isolation air bladder footers. So, energy entering the system is addressed, and energy created within the system is routed out through mechanical means.

The rest of my electronics are isolated on air bladder supports and I am considering ways to drain internal mechanical vibrations from these components. My speakers are highly engineered to address vibrations and I have added supports to my wooden suspended floor to reduce its movement.
 

rbbert

Active Member
Dec 12, 2010
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Reno, NV
#9
Wood, regardless of type and weight, is inherently resonant, never dead, so in most (or all) cases wood alone will not isolate or damp vibrations. Many speakers designers use this to "voiice" their products; others, notably Rockport and Magico, either avoid wood or supplement it with a variety of materials in an attempt to avoid resonance totally.
 

rbbert

Active Member
Dec 12, 2010
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#11
Everything resonates you just need to find the frequency.
Keith.
True. I should have added that wood always resonates at frequencies well within the audible range.
 
May 30, 2010
13,964
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Portugal
#12
Connect your power amplifier to a power 4 ohm resistor and play some music at high level. In many amplifiers you will hear very low distorted music coming from the amplifier. You can do this experiment yourself with your equipment, I did it more than once. T03 power transistors are excellent transducers!
 

DaveC

[Industry Expert]
Nov 16, 2014
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#14
Whether it's just ironic or confounding, playing music through our stereos causes the equipment that reproduces it to distort the thing we love. Everything vibrates. I'm not sure how to think about the issues other than starting at some high level, like you did, then breaking them down.

Wrt your #4, vibration management, it seems one has at least two choices that are not equally available or mutually exclusive:
a) before the fact: prevent vibrations from arriving at their target and/or
b) after the fact: attempt to mitigate/reduce vibrations from further impacting the things they are acting upon.

Examples of the first case are using acoustic treatment at reflection points to prevent time lagged vibrations from arriving at our ears later than direct sound, or putting equipment in another room where it is less impacted by air born vibration.

For the second case (b) it seems there are (at least) two non-mutually-exclusive options:
i) direct vibrations away from or out of the thing they affect without providing a pathway for their return, this is the 'draining diode' approach claimed for such things as spikes and cones. Or,
ii) convert the vibration from mechanical energy to some other form of energy that does less or no damage, such as converting movement into heat, typically through friction as done by Stillpoints or various rollerthingies, as well as by use of viscoelastic material, where mechanical energy pushes the viscoelastic out of shape until it returns to shape.

Some racks use both approaches.

I'd be interested if you have examples that fall outside this simplistic analysis and whether it can be modified to incorporate them? I don't know if this sort of categorizing will help, in addition to your analysis.



Side note: I thought it interesting that you mentioned "current running through wires" as a cause of vibration. I had been wondering if we could consider the distortion caused by skin-effect as a product of vibration - the "change" of energy through dielectric absorption and relaxation introducing "music from the past", as it were, onto the current signal. (Maybe it is more an issue of semantics.) Running a circuit parallel to the signal wire with the same signal on it and in sync, reduces the skin effect (as elegantly executed in Shunyata's Zi-tron technology, or less elegantly in the LessLoss tunnel bridge.) The point being to wonder if this is also a type of approach different from i) or ii) above that can be used to fight vibration's distortion.

Rather than putting equipment in another room, it is possible to treat it to be less susceptible to vibration through mass loading, possibly combined with damping. One example is a weight sitting on a component with a viscoelastic material between the mass and the component. For vibration transmitted by the floor, footers that incorporate damping can help, as can CLD platforms... and this is where cones or other methods of direct coupling fail, they allow vibrations in the floor to enter the component or speakers where it will cause problems.

As far as cones go, they are often misunderstood. I've regularly heard the line that cones work through minimizing contact area with what they are sitting on, which reduces friction, thus minimizing vibration entering the coned device. The issue is the cone will mate with the surface it's sitting on, greatly increasing friction and coupling the coned device to whatever it's sitting on and doing the exact opposite of what is intended. Those that see the floor as a "sink" instead of a source of vibration believe coupling to the floor is a good idea but even if it's a concrete pad it's still a source of vibration. This is why spiking speakers to the floor is always a bad idea.

On your side note, this is the concept litz wire works on and has been around for a long time. The issue is it takes more than parallel conductors. If you bundle a bunch of individually insulated conductors in parallel you will still get skin effect as if the wires were not individually insulated. It also takes braiding and/or twisting the wires in such a way that they all share the same position in the bundle, i.e. there are no inner or outer wires. This is a separate issue from the effects of the dielectric although both are related to the frequency of the signal so it could be thought of as an issue caused by vibration, although it's not exactly the same... the frequency of an electrical signal is not a mechanical vibration. Although it can cause them in certain circumstances, i.e. transformers... In any case myself and many others find value in damping electrical components to prevent the electric signal from causing mechanical vibrations, potting trafos and applying damping materials to capacitors, coils, and lengths of wire.

Viscoelastic material also converts mechanical vibration into heat via the hysteresis properties of the material, or internal friction.

One interesting aspect of damping audio components is sometimes it can produce poor results, as in it is possible to overdamp components, especially wrt AC power. It seems that using too much or too soft of a viscoelastic material can suck the life out of the music, making it sound dull, dark and closed in. I wonder if anyone has any theories on what's going on there? Most people have figured this out and go with damping material of fairly hard durometer for it's intended purpose in an attempt to tune for this effect. Furutech, in their top of the line connectors, feature stainless steel combined with carbon fiber to control vibration. The mating of the two dissimilar materials, both of which are relatively hard, damps the vibration in a way that is extremely effective for audio use. Many of their connectors are offered with brass or stainless/carbon bodies, having the exact same internal parts. These connectors sound VERY different from one another, especially the FI-50/FI-52 line of AC plugs, to the point it's hard to believe they are essentially the same connector! And all because of the damping properties of the connector body!
 

tima

[Industry Expert]
Mar 4, 2014
259
15
18
#15
Rather than putting equipment in another room, it is possible to treat it to be less susceptible to vibration through mass loading, possibly combined with damping. One example is a weight sitting on a component with a viscoelastic material between the mass and the component. For vibration transmitted by the floor, footers that incorporate damping can help, as can CLD platforms... and this is where cones or other methods of direct coupling fail, they allow vibrations in the floor to enter the component or speakers where it will cause problems. ...
Sure, and thanks for your comments. I was not advocating any particular method or weighing its pros or cons but thinking about a way to categorize vibration management in order to organize (my) thought about the subject.

At a high level: One can take the component away from the vibration (EG putting it in another room) or take the vibration away from the component.

On your side note, this is the concept litz wire works on and has been around for a long time. The issue is it takes more than parallel conductors. If you bundle a bunch of individually insulated conductors in parallel you will still get skin effect as if the wires were not individually insulated. It also takes braiding and/or twisting the wires in such a way that they all share the same position in the bundle, i.e. there are no inner or outer wires. This is a separate issue from the effects of the dielectric although both are related to the frequency of the signal so it could be thought of as an issue caused by vibration, although it's not exactly the same... the frequency of an electrical signal is not a mechanical vibration. Although it can cause them in certain circumstances, i.e. transformers... In any case myself and many others find value in damping electrical components to prevent the electric signal from causing mechanical vibrations, potting trafos and applying damping materials to capacitors, coils, and lengths of wire. ...
I acknowledge what you point out about Litz wire but I was not trying to describe Litz wire or the way that it works. The principles used by, for example, Shunyata and Lessloss to address eddy currents and eliminate or mitigate skin effect are different. (Although Shunyata's earlier Helix series of cables did tackle this through sophisticated braiding.) Without meaning to be a tout, take a look here for a description of the Lessloss effort. (Shunyata's patented Zi-Tron solution uses the same principle but is more elegant (no external power required) and yields better sonics.) Whether to regard eddy currents as an example of "vibration" is probably open to debate, but that's what I was lead to think about from Peter's mention of current passing through wire. It was this 'canceling' technique about which I wondered if it is another way to address vibrations and if there might be ways to apply the idea more broadly and not necessarily with electro-magnetism.

And I do agree, one can over-damp. Put too many damping rings on a tube and music can sound a bit closed-in and less vivacious.
 

DaveC

[Industry Expert]
Nov 16, 2014
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#16
Thanks for the link tima, I am guessing you are the author? If so good job writing your review!

I think there is a lot of merit to the ideas discussed although I prefer simpler solutions. I think, like quantum mechanics, that physical phenomenon can be seen from different points of view as they all share similar operating principles at the core of it all. Heat transfer, beam bending, and much more can all be described in very similar if not identical mathematical terms. Of course the example that comes to mind most of all is Thiele-Small where physical phenomena is converted into equivalent electric circuits. So I do agree that electric phenomenon have a vibrational aspect to them and can be studied in terms of vibrational phenomenon which, like Thiele-Small, could open the door to unique ways of perception which could be very useful. Eddy currents are induced by changing magnetic fields, so they can be thought of as a form of vibration or an effect of electrical vibration, possibly in terms of a resonance... with skin effect being a primary effect. Very interesting and good food for thought...
 

PeterA

Active Member
Dec 7, 2011
4,881
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38
North Shore of Boston
#17
Can someone address the notion that when isolating a component, say an amplifier or turntable, with a product like an air bladder (Vibraplane), springs (Minus K) or active servo devices (Herzan), that it helps one problem but may cause another? Does isolation also trap internally generated vibrations within the component by eliminating an exit path for the vibrations to follow. So while addressing one type of vibration, one might exasperate another type of vibration.

This is why it might be useful to determine which type of vibration is most harmful to which type of component and then to try to deal with the problem in a systematic and ordered way.

There are distinct methods of dealing with certain types of vibrations: isolation, damping, mass loading, drainage paths, conversions to heat, etc. Are there ways to combine these methods to achieve a more holistic solution? Say draining vibrations from components into a mass loaded rack and then isolating the rack from floor borne vibrations? Or using something like a spike or Stillpoint under a component but on top of an isolation platform?

There also seem to be distinctly different approaches to certain problems. Some people advocate coupling speakers to the floor, while others advocate decoupling them. Are we left to simply try the options and then decide which works best for us?
 
May 30, 2010
13,964
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Portugal
#18
(...) There also seem to be distinctly different approaches to certain problems. Some people advocate coupling speakers to the floor, while others advocate decoupling them. Are we left to simply try the options and then decide which works best for us?
IMHO yes. If you can have the opinion of the equipment designer or manufacturer and describe him extensively your conditions you can probably have a starting point.

The effect of vibrations on electronic equipment have been exhaustively studied for many purposes. However as far as I know no one one tried to correlate them with stereo sound quality in absolute. Even in speakers opinions and choices are changing fast. The best articles I read on the subject came from Goldmund ( they used several metals to mutually damp their metal speaker enclosures and created the concept of the mechanical diode) but it was long ago in french audio magazines and I do not have references on it any more.

As far as I have read and remember Nelson Pass never addressed such subject in the DIY audio forum where he often participates.
 

jfrech

VIP/Donor
Sep 3, 2012
1,536
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Austin
#19
Someone could place a solid state component on top of a subwoofer and you would never know it unless you looked.

Turntables are another story.
Maybe the subs frequencies aren't exciting the solid state components? I can absolutely hear what type of support my Ayre MX-R's are on...
 

jfrech

VIP/Donor
Sep 3, 2012
1,536
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Austin
#20
With all due respect to you, I don't think you can, have you tried comparing supports unsighted?
Gary is absolutely correct, with solid state equipment ,internal or external vibration is simply not transmitted to the devices output,
there are some interesting measuremtnts of vibration in equipment in this thread.
http://www.pinkfishmedia.net/forum/showthread.php?t=174095&highlight=microphony

Keith.
Keith, stop by sometime. I'll move the amps off my rack and put em on the floor or a few books or find a friend with a sub to put them on...it's not subtle. So I'm not arguing your point of "Gary is absolutely correct, with solid state equipment ,internal or external vibration is simply not transmitted to the devices output" I am arguing vibration and support are effecting something in my solid state amps. It's easily heard.

Peter, the OP, has his solid state amps on Vibraplanes for a reason...something is effecting solid state components and effecting how it sounds.
 

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