Turntable and Rack vibration control


Hi,
I moved from a Nouvelle Platine Verdier to a Loricraft Garrard 301. The big change with this move was that the Verdier comes with a terrific implementation of pneumatic suspension feet which kept the TT almost floating and hence great isolation from vibration. The result was always a noise/grain free playback and super clean backgrounds. With the Garrard, the plinth is typical custom made stacked birch ply with standard steel cones as footers. When placed directly on the rack the background is noisy, the images muddle up and overall music is not well sorted.

I do not expect the Garrard to be as quiet as the Verdier but I know it should not be this noisy either. In fact the Verdier also sounded noisy when I placed it directly on cones bypassing the pneumatic suspension feet. 

I use a Hutter Racktime rack which is not like an overbuilt audiophile rack. It is more like an open frame rack with lightweight supports. It is a bit like a Rega TT, not very damped or controlled. The rack has pointy steel feet which rests on brass spike plates (mine is an wooden floor). I guess this implementation is not sophisticated enough to keep away vibrations and let the TT play quietly. 

I am looking at two levels of solutions:
1. Replace the existing steel feet and brass plate with a quality vibration control footer below the rack
2. Replace the stock steel cone below the TT plinth with a better footer/platform.

I have tried Sorbothane, Squash balls kind of tweaks, while they reduce noise they slow down the music too.
I have also tried Stillpoints and Finite Elemente footers under the rack. They make the sound thin and metallic IMO. Platforms like Minus-K are too expensive so I have not considered them yet.

I am looking suggestions here, probably footers and vibration control devices that are more musically oriented yet well engineered like Shun Mook, Harmonix, SSC or something like an HRS platform ?
pani

Showing 16 responses by geoffkait

Everything should be isolated. Not only audio components and speakers but all the heavy items in the room, chest of drawers, bookcase, couch, big overstuffed chairs. The most cost effective way to isolate furniture is with Small DH Cones but any cones will suffice. Super DH Cones are probably not (rpt not) cost effective but would be the best sounding. Maybe check the tweak closet for any cones you might have tossed in there.

Wet playing LPs probably reduces stylus drag, assuming it’s an issue, but it obviously reduces noise and distortion. The audiophile’s favorite, including mine, wet playing combo was a mixture of distilled wate and ArmorAll and one of those cute little Audio Technica red velvet roller brushes. Lubricant, coolant and just plain surfing fun for the stylus. 🏄🏻

As I just posted on another thread about vibration the usual damping techniques, especially those employing soft rubbery materials, often fail to accomplish the mission. What is really needed for these stubborn cases is a method that allows the mechanical energy to exit the system rapidly, rather than stick around and reverberate inside the system. So, instead of attempting to muffle the vibration or control it with rubbery materials like Sorbothane it’s usually much more effective to employ either constrained layer damping or relatively simple devices like audio cones especially DH Cones, very hard materials, even crystals can be very effected in this regard. Or even, as suggested by the OP, Shun Mook Mpingo discs. Those devices provide a *path of least resistance," a mechanical diode, for the energy to exit stage right, as it were. 💃

You’re close, very close. You actually want to target the resonant frequencies of the platter, tonearm and cartridge, which are designed to exhibit resonant frequencies well below the lowest frequency of speakers, around 10 Hz to 15 Hz. So all you have to do is reduce or eliminate any vibration in the range 10 to 15 Hz. Vibration isolation would be a good place to start. 


jollygreenaudiophile2
The only problem with using any app. is the fact that no matter how fine the code is written, at the end of the day your still at the mercy of whatever your using collect data. In this case, conduct the vibrations to your device. All vibratometers I know of come with a dedicated "probe" just for vibrations. So what your doing is basically trusting the 23 cent microphone in your phone. Would you trust a frequency analyzer app to do room correction? If you do your probably going to have a dead spot below 40 Hertze. Why? Because your phones mic cannot read at that level.

>>>>>Huh? Whoa! A microphone? I’m afraid the microphone does not (rpt not) have anything to do with it. The microphone is for acoustic waves, you know, like voice, not (rpt not) seismic or mechanical vibration. The accelerometer in the phone is the device that detects and measures mechanical and seismic type motion, for example when you turn your phone on its side, the phone’s accelerometer detects the motion and corrects the screen display orientation accordingly. So the accelerometer(s) measures acceleration and by calculation velocity and direction are obtained. There are several reasons why some or most of these vibration apps won’t work for seismic vibrations, including but not (rpt not) limited to the fact that speakers do not (rpt not) produce any mechanical feedback below say 25 or 30 Hz.

Two turntables and a microphone....where it’s at?

cheerios




haroon
Proof is in the Pudding!

Download free App, "iSeismometer" (three axis sensitivity), put your smartphone on turntable platter and check out different turntables, racks and isolation schemes. Play loud music, use subwoofer, bang around with your foot to simulate footfalls; see the results for yourself. You’ll be surprised to find out what really works and what is just a myth.

One problem I can think of for most if not all "seismometer" apps downloadable to mobile devices is that they rely on the accelerometer inherent in mobile devices to determine accelerations, thus determine "seismic energy" as presented on the Richter Scale which as fate would have it is energy based but not frequency based. Therefore results using sesimometer apps can be misleading, or not helpful, especially in light of the fact that almost all isolation devices have resonant frequencies of around 2.5 or 3 Hz - if they’re lucky. So, actual isolation doesn’t kick in at all until frequency gets up around say 5 or 6 Hz and doesn’t become significant until around 20 Hz, obeying a low pass filter characteristic. Which is the usual range of "seismic vibrations."  0 Hz to 20 Hz - I.e., microseismic vibration. So, in fact, you might not be able to determine the effectiveness of a given isolation device - even though it is audibly effective.

Thus, the proof may or may not be in the pudding.
Here’s a little trick with marbles. You need three large size glass marbles and three glass or ceramic shallow bowls. The ones that are used as bases for those small incense candles are perfect. Then all you need is a glass or ceramic top plate which is placed directly onto the three marbles. Then balance everything with the component sitting on the top plate so the marbles are centered in their bowls/cups but free to move in any horizontal direction. For this to work correctly there can be no cables pulling on the top plate, etc. so the top plate and component are free to move very easily.

I also disagree about the EAR stuff. Very "weird" sounding. It looks like such good material, too. Oh, well, at least I tried. C’est la vie.
Actually granite won’t resonate or ring if it’s thick enough under normal conditions unless struck with a hammer or wrench. So my advice is don’t strike it with a hammer or wrench while music is playing and you’ll be alright. And if the granite slab is up on springs so much the better since the granite will then be isolated 99.99% from anything from the floor that could possibly make it ring. Besides the resistance to bending forces outweigh any risk of ringing. That's why the big boys like Newport and TMC use granite slabs on their uber expensive isolation platforms. 

Granite and cones is a little bit different story than a rigid rack. In the case of granite or say bluestone, it’s less expensive sibling, it’s really all about stiffness and harness, which are more desirable attributes than rigidity for isolation. You know, hardness for speed of dissipating energy from the system and the (stiff) granite slab to isolate against bending forces. There is also inertia benefit due to sheer mass of granite slab. Never take anything for granite. To improve upon the granite and cones place another slab of granite on top of springs on top of the first slab of granite, completing the Trifecta!

Racks per se can and do exacerbate structureborne vibration thus it makes more sense to skip the rack entirely and place the component of turntable whatever direction on a competent isolation stand on the floor, of course paying attention to how the component or TT is interfaced to the isolation stand and how the isolation stand is interfaced to the floor, preferably with extreme hardness cones. On the grand scale of things even tempered steel is not nearly as hard as say the special ceramic ones.