Help! Tweaking My Lovan Rack for new Big A**ed Transrotor Turntable!

Actually the word plane is correct since isolation occurs for ALL DIRECTIONS in the horizontal plane. Whereas the vertical direction is not a plane. Nor are twist, rock, roll. They are directions. Lets twist again like we did last summer!

Reporting in for a moment:

I just finished some more vibration testing with some of the materials I’ve ordered.

First: I am ordering a 2 1/2" thick maple base for the turntable to sit on.

So it goes: Lovan rack, 3/4" MDF blue-tacked to top metal brace of the Lovan rack, then the thinner original Lovan MDF shelf blue-tacked to that, for some stability. Then some sort of isolation feet between that and the maple block base/turntable above.

So I’ve wanted some isolation/vibration control to go between the lovan shelf and the new maple base on which the turntable will sit.

I’ve finally figured out what I want to do, based on tonight’s experiments.

The various isolation/absorbtion items I now have to play with:

1. Townshend Seismic Pods
2. Soundamped Steel Isofeet:
https://www.ebay.co.uk/itm/Isofeet-by-SoundDampedSteel-Set-of-4-in-black-ROUND-80mm-diameter-/201230...
3. sorbathane pads (1/2" thick)
4. Vibrapods - the classic - newly arrived.

So I’ve been wanting to isolate the turntable/base both in a way that reduces vibration getting to the turntable (e.g. from the ground the stand is sitting on) and also minimize any vibrations associated that the turntable/motor may be making.

To this end I’ve been experimenting again with the siesmic vibration ipad app in various ways: placing the ipad on a surface and then knocking around the surface to see the measured spikes in vibration, the putting the ipad either directly on a set of one of the above devices and knocking around the surface again to see if there’s any reduction in sound transfer. I’d also rap the ipad itself, to see if the device it’s sitting on reduced any of that vibration. Also, I’d do the same placing the ipad both on a butcher block I have, with various isolation devices under the butcher block, as well as putting the ipad on the platter of my older micro seiki turntable, and doing various experiments with the isolation devices.

My previous results showed the Townshend Seismic Pods were easily the best at stopping vibrations getting to the base. However, there was little reduction in the vibration when rapping the block or ipad sitting on the Pods. In other words, little vibration absorbtion that I could see in terms of absorbing from the turntable/ipad itself.

After watching some of the sounddamped steel demo videos on youtube (they looked impressive) I tried to re-create some of them. Today I used my kid’s fairly low tech powered toothbrush, which creates a rattly buzz.

I used it to measure the transfer of vibration from a surface that the ipad sat on, and also directly vibrating the ipad itself (pressing the running toothbrush on the ipad, and observing the measured vibration).

At first this wasn’t yield really significant results either way. But then, I tried holding each of the above isolation devices and pressing the vibrating toothbrush on to the device in my palm. The one that really stuck out as the worst in this test, by far, was the Vibrapods! Pressing the buzzing end of the toothbrush into my palm I felt a very strong buzzing and vibration. Putting a Vibrapod into my palm them pressing the toothbrush on to it created just as much, if not more buzzing. The whole vibrapod really buzzed badly.

Now...previous to this, if I placed the ipad on a wood surface and then pressed the vibrating toothbrush beside it, and then placed the ipad on the vibrapods, I could see a definite reduction in vibration. So they certainly do something there. But in terms of stopping direct vibrations, it felt like the toobrush vibration went right through the Vibrapods. Not too confidence-inspiring.

The sounddamped steel Isofeet, however, were quite impressive in this test. Placing one on my palm really reduced the sensation of vibration from the toothbrush! They work!

Same with the Townsend Pods.

Then I finally hit on the magic combination. I put an Isofeet disc on top of a Townsend Pod in my palm, did the toothbrush test and wow...amazing reduction in vibration getting through!

Then I tried this combination in various ways - the ipad sitting on it, or that combo holding up the turntable/butcher block, etc. Testing both knocking a nearby surface, tapping the turntable itself, and pressing the toobrush against the ipad/turntable.

In every case, the Townsend/Sounddampted combo excelled in reducing vibration, be it reducing transfer from the surface to whatever was sitting on the combo, AND reducing vibration of the turntable/ipad when they were tapped directly or the toothbrush was pressed against them.

This is exactly the results I was looking for. And got even better when I created a sandwhich: The Townsend Pod sitting on the sounddamped steel disc, and one on top of the Townsend Pod. The difference in how much I could measure, and feel the reduction in vibration was very impressive.

So....I plan to use a sandwhich of the Soundamped steel discs and the Townsend Pods holding up my Maple Block turntable base.

I also plan to order a few more Sounddamped steel discs to sit under the feet of the turntable. I’m even looking at the Sounddamped steel Soundeck turntable matt, which uses the same soundamped steel:

http://soundeck.bigcartel.com/product/sundeck-aluminium-black

That may be over-kill for an already high-mass platter like the Fat Bob, though.

I submit that rapping or knocking the stand or the iPad seismic app is actually ineffective for determining whether a particular stand design is effective or whether seismic vibration is getting into the component, especially a turntable.

First, as far as I could tell, the seismic apps are insensitive to the very lowest frequencies - the ones that are the biggest problem. These are the ones in the range of 0 to 20 Hz. Second, rapping or tapping a surface doesn’t generate the seismic vibrations of concern 0-20 Hz, only higher ones, ones that the turntable is relatively immune to, including acoustic waves. For turntables, the resonant frequencies of the tonearm, cartridge and platter are usually around 10-14 Hz, so the isolation stand resonant frequency should be much lower than 10 Hz to be able to significantly attenuate those frequencies 10-14 Hz, assuming a mass-on-spring device, since it’s a low pass mechanical filter. For example, if your isolation stand has a resonant frequency of around 4 Hz, attenuation at 10-14 Hz will be only around 50%. But if you can get the resonant frequency of the stand down to 2 Hz the attenuation will be up around 80%.

Of course the analysis is more complicated, since there are six count em directions of motion that should ideally be isolated. Holiday Hint: The effectiveness of isolation in a particular direction is proportional to how easily the component is able to move in that direction. This is why one should be wary of overdamping. Thus, undamped springs can be more effective than rubbery type materials or rubber air bladders or air springs.

@prof

I’ve had excellent results with the Funk Firm Achromat (5mm). As you are experiencing...there’s research, there are opinions, then the most important thing is action. In your system, they may not all align. Good luck!



@bdp24

When I first saw Lucinda refer to her song list/lyrics at a show, I was kind of taken aback. Then I realized, it’s a good thing for all.

When members say " I would" or "think about it" in the context of them never actually trying their proposed method, should be of taken in the context of the effort on their part in which it is mentioned...in their own systems.

Not saying this info is invalid, just that "action" speaks louder than words even in audio terms. In the end, your action is all that matters.