An interesting demonstration of turntable vibration and damping

rothwellaudio

rothwellaudio

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I just happened to stumble across this video:
I was impressed by use of a small motor as a consistent vibration source and the use of a simple aluminium tray with lightweight balls (not exactly sure what they are) to show clearly how much vibration there is.
The damping platter does seem to be very effective, but I thought the test procedure is simple enough for anyone to adopt to test their own tweaks and modifications.
Incidentally, it also shows how ineffective non-suspended turntables are at isolating vibration.
Btw, I have no affiliation with the company selling the product.
 
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Good demo.

I think a lot of people underestimate the importance of isolating the TT from seismic vibration. I live in the country with ZERO traffic, I moved the TT out of the lounge room into my spare bedroom and made an isolation station, the difference in spacial information was enormous.

IMG_20210817_162532151.jpg
 
The Plinth material is a large part of reducing vibration to the stylus. I went to a guys house and he had the volume cranked up on his enormous system with a Vpi TT and suddenly there as a huge feedback that tripped his breakers. I tried telling him it was because of his TT design, but since it was the highly rated, high dollar Vpi, he didn't believe me,, saying something about
'It's not coming from my 38 pound TT" . The plinth needed to be a slab of granite or marble weighing 200 pounds.
 
I would be curious to see what damping effect the stock rubber mat had, the comparison in the video was between no mat and their mat. I never run any table without a mat so this demo doesn't really convince me that their product is superior to a rubber/leather/cork mat :dunno:.
 
Interesting. Good demo for showing what is transferred through to the platter. I wonder about the analogy to the arm mount.

Silence in the background is rarely fully appreciated until it is experienced. IOW, TT background noise is only recognized once it is removed.
 
Hobie1dog said:
The Plinth material is a large part of reducing vibration to the stylus. I went to a guys house and he had the volume cranked up on his enormous system with a Vpi TT and suddenly there as a huge feedback that tripped his breakers. I tried telling him it was because of his TT design, but since it was the highly rated, high dollar Vpi, he didn't believe me,, saying something about
'It's not coming from my 38 pound TT" . The plinth needed to be a slab of granite or marble weighing 200 pounds.
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Personally, I'm not a fan of the "just make it massive" school of thought. A proper suspension system makes a lot more sense to me. One thing the "massive plinth" designs don't address is vibration from the motor, whereas a suspended design breaks the transmission path from the motor to the platter.

Of course, the flimsy plastic plinth in the video is just asking for trouble.
 
rothwellaudio said:
Personally, I'm not a fan of the "just make it massive" school of thought. A proper suspension system makes a lot more sense to me. One thing the "massive plinth" designs don't address is vibration from the motor, whereas a suspended design breaks the transmission path from the motor to the platter.

Of course, the flimsy plastic plinth in the video is just asking for trouble.
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I'm a fan of it because of the vibrations in the air and their ability to cause the TT to pick them up and transfer them to the tonearm and stylus. In a proper system capable of a full 20-20K in -room response at 110db (real life reproduction of the actual event), there is lots of air moving that can induce things of low density to vibrate. That's why 90% of the 100K dollar tables all have massive platters. And the motor is in a separate unit with only the belt connecting the two. The tables job is just to maintain exact speed and isolate from vibration.
Years ago I had a guy who was going to give me a pool table, i think the slate was 1 1/2" thick. I wanted to cut it and make a 3 layer sandwich of it with cork in between the layers of slate for the plinth, then have the platter mat with the same thick layer of cork. Should have been a good design when hung from the ceiling on cables.:)
 
Hobie1dog said:
I'm a fan of it because of the vibrations in the air and their ability to cause the TT to pick them up and transfer them to the tonearm and stylus. In a proper system capable of a full 20-20K in -room response at 110db (real life reproduction of the actual event), there is lots of air moving that can induce things of low density to vibrate. That's why 90% of the 100K dollar tables all have massive platters.
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There's absolutely no reason why a suspended design can't has a lot of mass too. A lot of suspended designs from yesteryear such as the Linn Sondek and those from Acoustic Research were too light (in my opinion) and the sub-chassis bounced with too high a resonant frequency. There's no reason why issues can't be addressed, and they have been in some modern turntables.
SME_Model_3012_Turntable.jpg

Hobie1dog said:
And the motor is in a separate unit with only the belt connecting the two. The tables job is just to maintain exact speed and isolate from vibration.
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Unfortunately, it isn't only the belt making a connection between the motor and the platter - it's just a visual impression. The motor and the main plinth both sit on the same surface and vibrations travel between the two via the surface they sit on.
 
so basically you're suggesting both mass loading and suspension decoupling. Turn it into a Rolls Royce basically.
 
As mentioned above, what does the aluminum pan sound like with the stock mat?
Quite likely not as theatrically entertaining other wise he would have continued the demonstration.

Just pointing out the obvious.
 
rothwellaudio said:
Yep :thumbsup:
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Well the suspended table I have is a SOTA Cosmos Eclipse. Weight is 44 pounds with the platter being a composite formula weighing 9 pounds and a sub chassis made from aluminum alloy. Looks like it meets that requirement of high mass and suspended design. Also uses a vacuum clamping system with a thin material covering the platter that allows for air flow yet protects the record.

cosmos-dark.jpg


But I also have a Scheu Audio table that weighs 65 pounds and is a non suspended design. It is not possible to make direct comparisons because I cannot easily move arms and cartridges. However, these tables sound very very similar despite their differences. in design.

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That looks interesting. I have a Thorens TD166MKII that I’d like to connect to my other rig, but has been in a bit of limbo as I thought there was still a tiny bit of motor noise my stylus/cart was picking up.
 
Coolhandjjl said:
That looks interesting. I have a Thorens TD166MKII that I’d like to connect to my other rig, but has been in a bit of limbo as I thought there was still a tiny bit of motor noise my stylus/cart was picking up.
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I have the same table and got an improvement in noise reduction by changing to a rubber mat. The original Thorens mat on mine was almost feeling like plastic. A very hard rubber. I tossed on a mat from a Sony donor table and found it much better.
 
Hobie1dog said:
I'm a fan of it because of the vibrations in the air and their ability to cause the TT to pick them up and transfer them to the tonearm and stylus. In a proper system capable of a full 20-20K in -room response at 110db (real life reproduction of the actual event), there is lots of air moving that can induce things of low density to vibrate. That's why 90% of the 100K dollar tables all have massive platters. And the motor is in a separate unit with only the belt connecting the two. The tables job is just to maintain exact speed and isolate from vibration.
Years ago I had a guy who was going to give me a pool table, i think the slate was 1 1/2" thick. I wanted to cut it and make a 3 layer sandwich of it with cork in between the layers of slate for the plinth, then have the platter mat with the same thick layer of cork. Should have been a good design when hung from the ceiling on cables.:)
Click to expand...

The problem with mass alone is the potential energy storage. If the resonant f of the mass is at some frequency that is excited by local environment then the whole mass will build resonance albeit slowly but this resonance will also decay slowly. Now put that mass on a spring with a lower fr than the plinth mass and you have very well decoupled system. This is principle behind the isolation stand I posted in #2.
 
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