Vibration control experiments - tubes and bearings

[brucew268]

I've been trying various combinations of isolating my equipment with inner tubes and precision diy roller-blocks, with some surprising results.

Under my Calyx DAC, the roller bearings significantly increased detail but hyped up the grain. That was balanced back out when putting an MDF board and a barely sprung inner tube under the roller bearings.

Under my laptop (same shelf as DAC) the roller bearings did 90% of the job with no harmful artifacts or tone control. (Surprise.) Adding the inner tube helped the last 10%.

Having a full complement of roller-bearings, MDF, and inner tube under both DAC and laptop brought a little hardness back to the lower treble -- upper piano register & cymbals. (Surprise.)

It worked best to have the inner tube under the laptop OR the DAC, but not both. (Surprise.)

In the end the piano was most realistic with the bearings/MDF/tube under the DAC and just the bearings under the laptop.

I did get some benefit under my Classe preamp, also, though not as much as under the sources.

I can't explain why the full complement under both DAC and laptop was a step backward, or why the best combination had the inner tube under the DAC and not the laptop.

BTW: the laptop plays from memory buffer, but does have a fan and a hard drive that doesn't spin down immediately. The rack is steel but filled and fairly well damped.

These efforts separately or together had greater effect for me than squishy feet (ultra soft rubber, moongel, vibrapods). And they all worked definitely better than hard cones which I always found to acts as tone controls, messing up the balance and nuance of the sound as it accentuated detail in certain frequency ranges.

[brucew268]

It occurs to me why the air suspension under the laptop was not as effective. There was no mass load over the inner tube, just the laptop and a light, stiff MDF board. Total weight of 2.8kg over the laptop's,inner tube. The Calyx, though provides its own reasonable mass totaling 4.8kg over its inner tube.

I could use a heavier board under the laptop, raising it from 2.8kg to 4.2-5kg. Or if using some lead, could get it to 10kg.

Any experience with the effect of various mass loading over inner tubes (including Seismic Sink)?

[brucew268]

I ended up making an MDF laminate board filled with kiln dried sand. This brought the combined weight of platform and laptop over the inner tube to 5.5 kg... and this really gave a much more realistic sound to the piano treble and to cymbals... especially on digital recordings such as John Bunch or Ray Brown, Gene Harris & co.

So it turns out that going from a CD player/transport to a laptop source does not remove the vibration issues, whether because of the fan, spinning drives, or something else.

[synsei]

Interesting observations Bruce ;)

[AlfaGTV]

Resonance and vibration caused by acoustic feedback can never do any good, but the improvement mentioned must of small importance in relation to, say, a change of speaker cable or amplifier?

Please try and quantify! :)

Regards //Mike

[jandl100]

I'm halfway thru trying Vibrapods under my speakers.

See Abso!ute Sound review here (http://www.vibrapod.com/Reviews/tas.htm)

http://www.positive-feedback.com/ambackissues/images/vibrapod_copy.jpg

I ordered two sets of 4, but Analogue Seduction only sent 1 set :doh:, so I have 'pods under the rear of the speakers only at the moment (I have the speakers slightly tilted forward anyway). Hopefully the other set will arrive today.

To my surprise (I'm not a great believer in damping, in general, finding that it often sucks the life out of the sound) the results so far are very positive indeed. My wonderful speakers are a significant bit more wonderful!
Detail and imaging/focus are improved, and the top end is just a tad smoother (in a realistic kind of way). Very pleased, I am, and looking forward to trying the full Vibrapod treatment once the remaining 4 arrive.

[brucew268]

I would imagine that a change of speaker cable or amplifier could result in a more siginificant change. Yet two considerations might be had:

The inner tube, heavy platform, & roller bearing cost £51 for one component extended to only £81 total for isolating 3 components. That is FAR less than the cost of a cable change or amplifier change.


The problem with degrading sound would still exist, especially with the laptop. An amplifier or cable change might bring bigger change, but that would only compensate for the problem with the laptop vibration. Whereas the inner tube/roller bearing approach actually takes steps to resolve the problem rather than compensating at another point in the chain.

I've tried Vibrapods with some good effect but not so great as using the air/bearing isolation... certainly less fiddly.

In general I did not hear a huge change in a lot of my music, perhaps because I have a pretty solid equipment rack spiked to a concrete floor. Though when A/B listening I could sense more '3D' detail and 'there-ness' when I isolated some components, and 'Not' when isolating other components. The key difference was that in some recordings that have a lot of piano or cymbals, and when listening to digitally recorded material (DDD), the presentation before seemed a bit opaque and flat. The piano and cymbals were rendered a bit cold and glaring, and a soundstage with no depth. (This was not so much a problem on CDs of classic jazz groups from the 50's and 60's.) So rather than taking a 'tone control' approach, I looked for the source of the problem. Some was due to being too close to my Sky+ box (RFI or EMI), but much turned out to be due to vibration issues.

BTW: I've always found hard cones to increase perceived detail but to skew the frequency balance and mess up the overall realistic nuances and balance of the music. Roller bearings without vertical suspension (inner tubes) have a similar effect on my analog gear but not so much on the digital source.

Separately, I don't consider an isolation approach to be the same as a damping approach. And I agree that damping can easily suck the life out of the music. Previously I've used some Dynamat on the case of the preamp and the CD player, and found that moderation was called for. Too much and the life was taken out. A little Dynamat really helped the component cases... and I've kept those in the system for 15 years. On welded steel equipment racks I've also used sand (hollow legs) and Dynamat (cross bars) to keep them from ringing and transferring that to the components.

[jandl100]

Separately, I don't consider an isolation approach to be the same as a damping approach.

Well, not always. But it can be.

Inner tubes and other squishy items will damp as well as isolate, whether or not that is the intention.

[sq225917]

Bruce maybe the laptop doesn't need isolating maybe the HD vibrations need sinking...

[brucew268]

"Sinking HD vibrations" as in "synchronising High Definition vibrations," or as in "draining away Hard Drive vibrations?" If you mean the first, I would guess that is a joke. If draining away Hard Drive (and fan) vibrations, then I see it likely that the vibrations produced in the laptop need to be drained away or damped and also that they need to be isolated from the rest of the components in the rack which would be corrupted by the laptop vibrations. Either way, this seems to be doing the job.

(I first got onto this track by noticing that the sound improved somewhat when I temporarily moved the laptop off of the equip rack and onto a spare end table. Putting squishy absorptive feet onto the laptop and putting it back on the rack did not really help much.)