Damping transports to kill vibrations sounds and improve signal (jitter)?

[halcyon]

I pledge my case to the wise people of the DIY Audio forum.

I have used the search and read the available threads on damping (quite a few of them, varying from loudspeaker to transport to shelf to amp implementations).

However, I believe I have somewhat specific needs.

I'm building a test system to measure audio & data cds (burned and original) using computer equipment. Just off-the shelf drives and readily available software.

The same system also works as my audio source (using my RME DIGI 96/8 sound card) when I work on my computer.

I'm come to realize that I need to control vibrations due to at least the following reasons:

1) Our building is near underground construction with frequent blasts that shake the whole building. These cannot be good for the equipment and for my tests.

2) Most cd-rom and dvd-rom drives, when hooked up to the computer chassis, vibrate a lot, causing vibration related rattling and additional sounds that I would like to damp.

3) I would like to improve on the readability of the drives by helping them stay more stable even under high speed rotations (cd-roms and dvd-roms are some times tested at quite high speeds for certain purposes)

4) In addition, I'd like to help my poor sound card and it's crystal to become less prone to microphonics from the floor and hopefully from inside the computer (the moving components inside my computer).

I have already looked at the wide variety of materials available. Trade names like sorbothane, deflex, microsorb, norsorex, vibrapods, tenderfeet, etc.

Often I don't even get the actual material that is being used, just a trade name. Many of the data available is purely anecdotal, because it's based on listening observations for transports and loudspeakers.

While I think this is the good way to analyze vibration damping materials for audio equipment, I also have the other needs as described above.

So, I'm calling on the collective wisdom of this forum to find out information on vibration measurements (energy damping / frequency distributions), contributions from what is done in other fields (say electromicroscopy) and just general comments on what kind of approaches I should test out. Like materials, sandwiching types, densities, equations and such. To narrow down my search for a good solution.

I hope not to spend huge amounts on the materials (up to €100 EUR or less) and hopfully be able to test only 2-3 different options.

I need both material to dampen the drives (to decouple or stabilize them from the computer chassis) and for the computer case itself (total weight c. 10-15 kg, not measured yet as it's under construction).

All comments, links, do's and don'ts are welcome.

Thanks!

[fastcat95]

Hello:

I think there is indeed value to damping
the CD drive system. Try the following:

1. Add mass to the unsprung (unisolated) part
of the drive system where possible, and/or the
base where the drive attaches, and add
suitable extensional damping sheets where
possible. Sheet thickness may be dictated by
the thickness of where the material will be
adhered to. Its good for the damping material
to be equal or greater thickness.

2. Look for places to add sheet damping material
or putty to the isolated structure part of the drive.

3. A surface sheet damping material applied around
the surface of the CD spindle motor may reduce
vibration from the motor.

4. Adding damping material to the disk clamp
mechanism might be helpful.

4. Plumbers putty might be useful to fill in nooks
& crannies around the drive mechanism.

Anything that reduces vibration getting into the
electronics, laser system, or the spinning CD in a
drive is worthwhile, and moving in the right
direction for better sonics.

Fastcat

[tobio]

HI
ONE OF THE BEST DAMPING I HAVE USED IS A PLATFORM HOLD BY CABLES FROM THE CELLING (IF YOUR WIFE AGREE TO IT)

UNDERNEATH THE PLAYER YOU CAN USE DAMPING OF YOUR CHOICE EITHER CONE PAD ETC.. ALSO MAKE DAMPING USING
ASPHALT PAD ON THE CASING AND INSIDE THE MACHINE

GOOD LUCK

TOBIO

[Rotellian]

Air bladder suspension. A DIY seismic sink. Using 2 slabs of marble and a slightly (important) inflated inner tube between the 2 (or 2 innertubes if necessary).

[EDUM]

Hello halcyon,

What are you exactly measuring? Error flags? radial noise? analog audio?
Did you already see vibrations influencing your measuring results?
If you have a decent cd drive you will be surprised to see how much it can handle.
If the drive is build in a PC, you are actualy building it in a quite hostile environment for clean measurements.

Please inform us a bit more

If you are on a thight budget and can not afford the massive marmor blocks used in electromicroscopy the sand filled wooden box is a (transportable!) alternative.

I am afraid the mini earthquakes generated by the blasting is a bit harder to tackle if(!) it influences your measuring results.

Ward

[Jocko Homo]

A guy that I once knew made a plastic disc for Phiips based CDPs, that went on top of the actual CD. (Yeah, it involved a bearing modification.)

Anyway.......the sonic results were exactly the same as reducing clock jitter: tighter bass, cleaner highs, less "digital sounding".

Bottom line: reduce all jitter.

Jocko

[pburke]

combine air bladder, heavy platform, damping and roller bearings and you will be amazed at how well your player can sound.

take a look at this page:

http://didnt.doit.wisc.edu/audio/CDP/cdp.html

quick picture to what I suggest

http://didnt.doit.wisc.edu/audio/CDP..._inch_base.jpg

low cost, works well even without underground blasts nearby