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  • Vibration isolationtwork devices

    Discussion in 'The main mechanical design forum' started by Blackmorec, Dec 23, 2018.

    1. Blackmorec

      Blackmorec Member

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      You’re no doubt all familiar with typical network devices that plug into the wall. When used in music and video streaming it turns out that major improvement in sound and picture quality can be had by swapping the cheap built-in switched mode power supply for a highly stable, far less noisy external linear power supply. This involves modifying the device to remove the SMPS and the built-in wall plug. This of course creates the first challenge of how to attach the device to the wall (the wall orientation is important). Secondly, in the presence of significant sound pressure the large surface area of the wall vibrates in time to the music. This vibration exites resonant frequencies within the network device, which suprisingly has major detremental effects on digital signals (I know it shouldn’t, but it does and its not subtle).
      so my challenge is to design an anti-vibration wall mount for small network devices. My current approach is as follows:
      Remove the internal power supply and associated wall plug prongs and mount the network device onto a rectangular piece of Perspex slightly larger than the device using a special plastic cement. At each corner of the perspex attach an o-ring . Form a slightly larger rectangle on the wall with 4 cup hooks to which i attach the O-rings. The o-rings are tight but the only tension applied is from the weight of the network device (ca 600grams) . I thus have a rectangle within a rectangle with the device suspended a few mm off the wall within the rectangle defined by the 4 cup hooks.
      A picture is certainly worth a thousand words but i’m wondering if you folk can picture what I’m talking about and come up with a few suggestions for improving the design? For example, do the O-rings need damping of some sort to convert the vibrational energy to work/heat?
      Thanks in advance for any insights you can provide
       
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    3. john12

      john12 Well-Known Member EngineeringClicks Expert

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      So, just so I'm getting this straight in my head - you're saying that the physical vibrations caused by the sound of the music causes electrical interference which interferes with the operation of the unit. Interesting!

      Could you mount the entire unit into some kind of dense material, like they use in high-end speakers? Or would that just actually amplify the vibrations?
       
    4. Blackmorec

      Blackmorec Member

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      Yes. For example, vibrating an integrated circuit or circuit board will interfere with its output in terms of the musical qualities it produces. When isolated from vibration the music gains in detail and loses that typical digital hardness and harshness.
      The loudspeaker approach does 2 things....it mounts the drivers in very stiff, well braced material and it mounts that material on spikes, which locks the housing into the floor and ensure that all the energy produced is acoustic
       
    5. GoodCat

      GoodCat Well-Known Member EngineeringClicks Expert

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      Сuriousidea but if my memory serves me, now there is a simple and effective design for this. It is a vibration reducing spike. The essence of the device is to make the contact of surfaces as minimal as possible and to minimize the transfer of vibration. I do not think that a continuous piece of perspex will work better. Ultimately, this solution will have more direct contact surfaces. Regarding the power sources I do not think that there are no solutions, I think that the line of professional acoustic systems uses components with significantly less electrical noise.
      More cheap devices simply use noisier and cheaper components. Also, in sound-sensitive technology, power supply sources with minimal electrical noise are used, I think from the point of view of cost, this is simply not applicable to low-cost speakers.
       
    6. Blackmorec

      Blackmorec Member

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      Dear GoodCat, thanks for the suggestions. Spikes are often used under loudspeakers and racks. They isolate from incoming vibration and drain any vibration generated by the component, so should be a good solution if I can figure out how to use them while maintaining the ‘on-wall’ orientation.

      Essentially what I’m doing here is using an internet + LAN based data stream to drive a high-end stereo system. The hi-fi electronics all use very quiet, stable, highly specified power supplies, but the data streaming is all based on cheap-as-chips consumer networking products that use the cheapest possible switch mode power supplies which produce lots of HF noise and residual ripple from the original 115/230V AC supply. This can be partially isolated by separating the mains supplies, using a dedicated consumer unit and radial to power the hi-fi and the regular house supply for the network but this is really only a partial fix as a lot of the noise is transmitted along the interconnecting cables and into components like the DAC. Best is to remove the SMPSs and use proper hi-fi grade ultra-low-noise linear power supplies plugged into the hi-Fi’s dedicated supply in order to avoid the problem completely
       
    7. john12

      john12 Well-Known Member EngineeringClicks Expert

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    8. tmark938

      tmark938 Moderator EngineeringClicks Expert

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      I dont know if this will help but years ago I invested in a company called NXT which was able to convert any object, a wall, door, etc, into a speaker system. The company was eventually taken over but I guess they would have had similar issues to the ones you are describing:-

      https://hifiwigwam.com/forum/topic/126093-nxt-panel-speakers/
       
    9. john12

      john12 Well-Known Member EngineeringClicks Expert

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      That's an interesting idea to use phone screens as speakers. It makes sense in a way (the screen makes up such a large part of the phone) but I wonder how well (or if at all) it works in practice. I wonder if it also stresses the screen material.

      I remember about 15-20 years ago loads of those 'speaker bug' devices came out that allowed you to turn glass windows into speakers... but they didn't really work that well.
       
    10. tmark938

      tmark938 Moderator EngineeringClicks Expert

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      In a previous career I saw a presentation of the NXT system which literally converted a picture frame hanging on a wall, complete with picture, into a speaker. You could not tell where the sound was coming from. Why did these technologies never take off?

      There was also talk of using this on mobile phones as you mentioned. This would surely cut the weight of phones dramatically?

      This thread is starting to turn into a version of "Tomorrows World" only we are looking back at a great technology which seemed to work but never hit the mass market.
       
    11. john12

      john12 Well-Known Member EngineeringClicks Expert

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      Tomorrow's World! Ah, that was a cracking show! I always remember that one where they had a car in South Africa with a flamethrower built in under the sides, in case you get car-jacked at traffic lights. Only people of a very specific age seem to remember it!

      I'm not sure why the flat speakers didn't take off - in my experience of them (only low-end consumer versions, not professional ones) the sound quality was really lacking and they didn't live up to the hype of working that well.
       

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