Nude Turntable Project

Hi Dover,

"A tripod is inherently more stable than 4 legs." I've read variations on your statement many times. But I wonder under which conditions it is true?

Is a tricycle more stable than a (4 wheel) wagon? Think about which one would be easier to tip over if making a sharp turn. But if that is an unfair example for a stationary object, then which one would be easier to tip with a shift in loaded mass while otherwise stationary.

As for camera tri-pods, I believe there are two reasons for their design. First, they are lighter and more portable than quad-pods, all else being equal.

But it is their second design feature that really gives the advantage. The three legs are splayed well outside the center point of the mass they support by angles. And I think it is the angles of the legs which provide the stability, rather than the number three.

Said another way (sorry, I'm trying to find the best way to express my sense of this issue and my question), if we have two small tables of the same weight and height, one has three vertical legs, the other four vertical legs, which will be more stable? If you push on the edge of the top surface, midway between any two legs of both tables, which one is more likely to tip?

Thanks Halcro, you beat me to it. .^)

Hi.

The Gyro testing table had 6 cast iron legs. Five of them were height adjustable with wooden decoupling pads. The sixth leg had no adjustment and it directly coupled with the concrete floor.

The Gyro testing table had 6 cast iron legs. Five of them were height adjustable with wooden decoupling pads. The sixth leg had no adjustment and it directly coupled with the concrete floor.

Interesting

gave this more thought. My current version Sp10/Armpod testing TT is different from the Gyro as it is a rigid structure bolted into the base/plinth. No provisions for height or level adjustments. All height and leveling adjustments are done by the three adjustable AT-616 pneumatic footers under the base/plinth. In this case the actual TT system feet are these footers and I use three.

As noted earlier the ET2 tonearm has its own leveling system independent of these feet for final leveling. I level the platter as best as possible then the tonearm. My SS legs are acting as supports and are not the actual TT system feet. I would want to keep all four for stability and rigidity. Sounds to me like trying this out means changing out one of the AT-616's for an alpha leg ? The one under the tonearm in the pic ?

Halcro/Pryso
We are in agreement on the "stability" of 3 feet.
My comments on stability are in the context of draining unwanted energy using single point mechanical grounding. I also assume the tripod is correctly designed for weight distribution to give stability and deal with rotational energy around the central axis. I also assume we are not driving the TT down to the grocery store and we are not in the habit of sitting on it.
Very few surfaces that the gear is mounted on are truly level, and in that context 3 feet will naturally load predictably, whereas with 4 or more feet they will have to be adjusted precisely to provide predictable loads through each foot. This is almost impossible unless you have pressure pads under each foot. The Mana stand manufacturers' recommended set up procedure for their 4 legged stands were to adjust the 4 feet with a stethoscope and tapping technique. Imagine doing this on each shelf as well as the feet ! And if you have a wooden floor that moves, you'll need to retune them each season.
In my 30+ years of audio I have applied the Goldmund mechanical grounding principles on all my components ( and many others ) and in all circumstances converting equipment ( TT's, amps, speakers ), speaker stands etc to 3 feet, single point mechanical grounding has yielded significant improvements in clarity, focus and the removal of resonances and tonal distortions.
In the Goldmund amplifiers, the mains transformers are grounded directly by bolting the transformers to the Goldmund footer, and the transformer is attached to the chassis by lossy connectors. The electronic circuitry is directly coupled to another of the 3 feet for optimum grounding and that foot has a lossy connection to the chassis. The net outcome is that each of these sources of resonance are single point mechanically grounded, and separate from each other, even though they exist in the same chassis. The chassis is decoupled from the others and grounded through the third leg. With non Goldmund amps the "alpha" leg is best placed under the mains transformer which is usually the largest source of resonance.