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System building 101A
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| JanVigne |
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Dynomat is using a shotgun to kill a fly in this case. Dynomat is essentially bituminous glop which adds mass more than damping. Bituminous means it is not too different than the old style asphalt covered roofing paper early diy'ers used inside their speaker cabinets. Think back to the comments regarding mass as a damping system. There are distinct downsides to mass in some usages. Sorbothane would be my suggestion for damping from the inside of a component. Much more hi-tech and, therefore, much more effective per square inch than bituminous glop. You should be able to find sheets of Sorbothane which you can cut up and use inside a DAC's chassis and it can then be removed wthout leaving any trace of its use if you sell the DAC. And you don't have to give the big boxes a single sheckel in tribute with Sorbothane. Plus the Dynomat can't easily be removed if you don't like the result.
But, before I even explored the more exotic materials for damping, I'd just fill a baggy or two large enough to cover the unsupported center portion of the DAC's top cover and give a listen. Mass is certainly one of those techniques which can vary with a little being sufficient and a lot being too much or vice versa. You can, of course, obtain the same results with a baggy full of sand though lead is heavier per volume of baggy than sand. If you use sand, double bag.
And, what we have yet to discuss is how you should go about the process of damping. You can expect only minimal results by damping the top plate if the resonance is still allowed to enter the component from beneath.
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| JanVigne |
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From JV’s post 4/28/2012 9:44:51 AM
“You want something heavy which has a permeable core material. What diy products commonly available can you think of that might fit those two criteria? “
"I use wooden blocks from kitchen cutting knife sets atop both the Rogue Pre-amp transformer and the Jerry Ramsey Audio Magic Stealth Matrix Power Line Conditioner. They are heavy for their size, made of wood and have tiny rubber feet."
While MW is content with his knife blocks, they lack the "premeable core" material I said would emulate the VPI Magic Brick. The wood on the Brick was merely a visual component of the product which made it somewhat more acceptabe in a domestic setting. The wood itself was never claimed by VPI to have any effectiveness regarding how the product operated.
http://www.tnt-audio.com/accessories/shakti_e.html
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| N1ck |
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Interesting Points Jan. My DAC currently sits on a one inch cutting board with 4 small holes drilled 1/2 inch on the bottom where I screwed 4 height adjustable isolation cones into those holes. I than had rubber centered inch thick platforms that I set the spikes into. I will try bags of shot lead and/or sand as I have lots of each currently in and around the center of the DAC. If I find that to improve things then I will make a hollow platform that I will fill with one of the two that will sit on top.
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| JanVigne |
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For smaller components such as half sized DAC's, here's an easy way to go about isolating the component from beneath. Most office supply stores have letter holders for sale, some even have the old fashioned wooden pieces. Use one of these - or any other open top box you care to - and fill it with sand up to about 1/2 inch from its top. Head to the home improvement store and ask them to cut a piece of 3/4 inch MDF to dimensions just slightly smaller than the box's inner space. Set the MDF on top of the sand so no sides are touching the box and set your component on top of the MDF. Make sure you have no gaps in the bottom of th box that would allow sand leakage. If you find a leak, seal it with a bit of kitchen caulking compound which you can buy in small tubes for small projects such as this. Pier One, Hobby Lobby, Target, etc. have plenty of larger size, open topped boxes to choose from for larger components.
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| JanVigne |
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We sort of lost our discussion of how isolation devices operate but to give you another quick idea, use air. Air is one of the most effective isolation devices available, you just need a consistent method for containing the air you will place under pressure. It's when you compress air that you gain its isolation properties. A very cheap method to accomplish this is to use tennis or racquetballs under your equipment. You can buy a bag of either at Target or a sporting goods store for a few dollars. Tighten the drawstring on the bag and toss it under your component for a cheap and easy isolation device. Dress it up if you care to but for a few dollars and a few minutes time you can accomplish a very good isolation system. Some people use inflated inner tubes meant for small wheeled vehicles such as wheel barrows. A very cheap device that you can probably find no more than a few blocks from your home is a hemmorhoid ring. Any drugstore carries these for about $12. Blow it up and put it under the component. Obviously, if you use a rubber or poly material, make certain the heat from the device will not melt the material. A thin piece of MDF or plywood would be sufficient as a heat guard between the component and the material. Aluminum foil placed on top of the MDF/ply will further reduce the heat transfer from the component.
Two things to be aware of; most inflatables do not hold a consistent pressure and any pliable rubber container will allow horizontal movement if the component vibrates in that plane. First, just watch the pressure in the inner tube/ring if you use one. The component will begin to sag at the point of the power transformer. The fix for this should be evident. But buy an inner tube with a reasonable size and thickness if you're intent is to use this under a relatively heavy component such as a 100 watt integrated amp. Bright Star marketed an isolation device a while back that placed the inflatable inner tube inside a bed of sand contained within a box. By combining the inflatable ring with the sand, the ring's expansion under weight was contained which rasied the resonant frequency of the isolation system and resisted the compression from more massive items placed on top of the plate separating the component from the ring. To compensate for the air loss over time in the inner tube, an extension had to be added to added to the air valve of the inner tube and run through the side of the box. This allowed the user to monitor and refill the inner tube to a desired pressure without first removing the component. That may be more effort than some of you are inertested in, but you can try the inner tube/ring device first and then decide how much effort is required based upon your observations of effectiveness.
A component which wobbles side to side is, in most cases, not that much of a concern if the wobble is actually draining energy from within the component. Placed under a pre amp or DAC, side to side wobble wouldn't really matter in most cases if the component's energy is being put into the larger surface of a support shelf rather than being contained within the component. However, the ideal is to drain the resonance away from the component and into some object that will convert the power transformer's energy into another form of energy. Here density and mass are the most easily accomplished alternatives to multi-thousand dollar isolation devices created for the medical or military fields. The plate which sits under the component should have a reasonable amount of density and mass and the OEM hard rubber or plastic component feet should be replaced with something a bit more high tech. The small Sorbothane footers sold by Audio Advisor would be an alternative as would the Vibrapods. Spikes and cones are always a choice. Low tech alternatives would be a wooden/plastic drawer pull which forms a ball or half circle where you would take advantage of the tangent of the curve.
I've settled on a simple combination of items available for a few dollars. I went to the plumbing supplies section of Home Depot and purchased Neoprene pipe caps - at HD they are called "QuikCaps". They have a small depression in the center of the top cover into which I place a racquetball or a halved racquetball with the cut side facing the component's chassis. Now I have a compliant footer which allows only minimal motion in either the horizontal or vertical plane, uses air as the main isolation device, will not leak, uses the tangent of the ball and cup concept, has dissimilar materials to break up resonant modes, can be adjusted for weight by buying larger or more QuikCaps and costs about five dollars apiece. Three of these go under my light weight pre amp while six go under the 65 lb Mac tubes.
I suggested these to MW also and in both systems these footers sit on top of a "plate" with some mass to it. In my system that would typically be three pieces of 3/4" MDF separated by the thinnest rubber shelf liner I could find at the dollar store. This forms a constrained layer damping system which resists movement in both the vertical and horizontal plane from beneath and from above and adds mass and density to the system to act as a final drain of energy. This system is adjusted for each component as not all need the same amount of mass under the component. The turntable is treated separately as any random motion of the support system will result in lower quality performance from a table. The CD player uses three Vibrapods with downward facing spikes draining transformer vibration into the MDF layering. I also use the VPI bricks on top of or above all transformers.
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| MW3 |
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Other than esthetics, which clearly is lost upon me in my set up, what difference does it make if one uses a simple brick used in construction sitting atop a small piece of wood so as not to damage a component's surface, versus getting a VPI brick?
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| JanVigne |
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You're misunderstanding the use of the word "brick" in the VPI product. The name of product was really just chosen for the appearance of the product as a passive, heavy, rectangular object with no moving parts. The mass of the brick was useful as a damping device but could actually collapse thinner top plates found on many CD players of the '80's. Placed under a component the density of the product provided a high level of damping to any structure borne resonances. However, both of those benefits can be had with a simple 5 lb lead diving weight available for a few dollars at any diving supplies shop.
The purported benefit of the Brick was its permeable core. The core was merely dressed up in a more aesthetically pleasing oak cover which had no claims of being anything more than a dressing material. The benefit of the core was to soak up - act as a drain for - any stray electro-magnetic fields originating in the component, most typically coming from the power transformer. It's well understood the power transformer will have a radiated field, as will all permeable coils, whether they are called coils, transformers or inductors. Looking at a crossover board you would see the individual inductors arranged in a way which places each coil's magnetic field at a 90 degree angle to the nearest adjacent coil to minimize interaction between the two devices. Your cables have a magnetic field which radiates 360 degrees around the cable. This is why it's suggested to either elevate the cable to avoid reflections back into the field or to, at least, keep your cables away from carpets made from synthetic materials which will create additional fields and then radiate the disrupted field back into the cable. This carpet effect is akin to tossing a stone into a pool of water and then a second later tossing another stone into the same spot except the effect is occurring in smaller, overlapping pools all along the length of the cable. It's also why some cable supports are reported to have a higher efficacy than others. In any location where the radiated fields exist, they will have a tendency to interfere with each other and with circuits in proximity to the field. In a system with sufficient transparency this may cause an audible smearing of time and phase elements which would affect the attack and decay of a signal along with the timbre of instruments and the nuances of performance. The usual "ABC's" of how to have a more realistic system sound.
Power transformers obviously have a much higher level of radiated energy than do cables and that field is in closer proximity to delicate electronic parts. Various transformer winding patterns have been developed to minimize the field or to direct the field's radiation in more controllable patterns than the generalized stone in the pool of water effect. Rather than using a simple and cheap E core transformer some manufacturers have gone to torroidal transformers characterized by a radiated field which tends to collapse inward on itself. A torroid also minimizes the common problem of core saturation seen in most coils when they reach their flux limits. However, while having some space saving qualities, a good torroidal power transformer is more expensive per Volt/Amp that would be a standard E core type. http://www.tabtronics.com/TECHNOLOGY/ElectromagneticBasics/ToroidalTransformerBasics/tabid/112/Default.aspx
Particularly where the surrounding circuits are of the very low level type - think phono pre amps in particular - the absorption of any stray fields by those circuits will affect sound quality by the addition of noise and time and phase shifts similar to those which occur in the cabling. A designer may opt for a Farady shield; http://www.wisegeek.com/what-is-a-faraday-shield.htm which is a relatively inexpensive to build solution or an external power supply which will also minimize circuit interactions. Trade offs naturally occur with each solution so whatever the designer selects will bring along its own set of disadvantages.
The permeable core of the VPI Brick is/was intended to act as a soak for the stray fields thereby keeping them away from the sensitive low level circuits found in many audio components. How effective the brick will be in any system depends on the level of the problem in any specific component and the transparency of the system overall to show improvements. With heavily potted transformers surrounded by a large metalic shield as you will find on the Mac tube amps, the benefits of the brick would be slight at best and unnoticeable in most systems. With a high powered solid state power amp the benefits are more likely to be noticed and with a pre amp containing a phono circuit, the highest expectations would be assumed. With a tube type phono section the additional benefits of mass damping from the brick might have some additional benefits in reducing microphonics. The trade off here is the additional mass of the brick may be too much for many footer type isolation systems.
The Brick hasn't been manufactured in years though there are common substitutes for the permeable core of the original Brick. The question I asked earlier was, can you think of any common devices - at reasonabe prices and easily found - which contain a permeable material? Lead diving weights would not count as a "permeable" material. Wood is clearly not a permeable material. By permeable I am not referring to any material which will absorb liquids or gasses.
The Shakti Stone has become the modern replacement for the Brick with further advancements made in the ability of a benign substance to affect the performance of a component. I linked to The Stone in a previous post. It too has become a somewhat controversial "tweak" along with Belt devices and magic clocks in that those objectivists who rely solely on numbers seem to have the ability to divorce from their purvey any numbers which do not relate directly to the component's circuitry as they see fit. A conventional THD measurement will not show the effect of the Brick or the Stone. Shakti does provide on their web site, however, some fairly convincing independent test results which would seem to confirm the effectiveness of their product on electronic cirucits.
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| N1ck |
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I played around with bags of Sand Box Sand, Shot Lead, and Compound Patch (A dense Cat Litter basically) and didn't a big difference between three substances. I tried bags on my DAC first. Sort of made the sound a bit dull. Tried it on my Media Center and I actually think I hear a slight benefit in clarity (jitter?). I thought at first it was just me tricking myself but after listening for a good few hours back and forth I left the Compound Patch on the top of the Media Center. I am not sure if this actually works but instead of using Wood I used a Plastic Utility box from Parts Express. Filled it right full, then screwed on the top. This is the box I used :
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=320-496
Not sure if this was a bad thing to use, but the dead weight on top of the Media Center seems to be helping.
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| dmitchell |
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I put weight on all of my components. I started this habit when Nuck was over one day, and while a CD was spinning, walked over to the rack, put his hand on the CDP, and pushed down.
The sound improvement was immediate and noticeable.
Ever since then I (carefully) place barbells on top of all my gear. Except for stuff with tubes sticking out, for obvious reasons.
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