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Machina Dynamica's Promethean Base
Theory of Operation




Mass-on-Spring System & Low-frequency Vibration
Promethean Base isolates moderate to heavy loads from sesimic type vibration - especially the 0 -10 Hz variety produced by Earth's crust movement, traffic, subways, tides, etc. Promethean is a "mass-on-spring" type device that isolates the component in 4 directions of motion (vertical direction and all 3 rotational directions) and exhibits resonant frequencies around 2 Hz. The advantage of a spring-based isolation system is that attentuation of low frequency vibration is provided, whereas rigid support structures, even heroically designed racks and stands, afford little or no isolation against very low (seismic type) frequencies. Those rigid structures allow very low frequency vibrations to be transmitted - and even amplified - to the component. Since sesimic vibration is shaking the entire building, the rigid rack structure is actually moving in concert with the building's motion. The mass-on-spring system, by contrast, does not allow trasmission of very low frequencies, according to the attenuation characteristics of the isolating system. Unlike most other mass-on-spring devices - such as air spring systems and air bladder/inner tube systems - Promethean employs specially fabricated mechanical springs with viscoelastic damping. These independent mechanical springs are arranged in a wide pattern for stability and effectiveness and can be easily moved by hand to obtain precise level of the component. The Promethean is (preferrably) mounted on special, super-hard NASA-grade ceramic DH Cones.

Stability and Center of Gravity
Promethean provides stability for moderate to high loads by employing at least 3 Special Helical Springs in a wide pattern between two plates. Maximum load for the 3-spring configuration (triangle) is 60 lb. However, very high loads are possible with the following caveates: due to center of gravity issues, the plates must be larger for heavier loads - and additional springs are required. For loads under 60 lb, 19x16 plates are sufficient, but for loads greater than 60 lb, both plates should be at least 20x24. For a 100 lb load, for example, 5 springs are required. Each spring is designed to support about 15-20 lb.

Seismic Vibration, a Brief Recap
Seismic vibration is a general term for very low frequency vibration produced by the constant movement of the Earth's crust, but can include vibration produced by traffic, subways, wind, tides, etc. Seismic vibration affects all electronic and mechanical elements of audio components and is quite deleterious to the sound quality. Most of the energy of seismic vibration is in the frequency range 0-10 Hz. Unfortunately, most isolation devices, pneumatic and otherwise, are relatively ineffective for the very lowest frequencies of seismic vibration because the resonant frequencies of those devcies are too high.

Rotational Forces
What are the "Directions of Motion" and why are they important? The Earth's crust movement (and other low frequency vibration generators like subways, buses, tides, wind, etc.) produces powerful mechanical waves that travel horizontally over the Earth's surface, a lot like shaking out a rug or waves traveling on the surface of the ocean. The vertical, horizontal and rotational forces acting on the building structure are illustrated below.



Seismic Type Forces Producing Structural Vibration with Rotational Components

Special Helical Springs
The Promethean employs specially fabricated steel compression springs designed by Machina Dynamica. These helical springs are available in two types - one type with very low spring rate for lighter loads (up to about 20 lb for 3 springs) and a stiffer type for heavier loads (up to 60 lb for 3 springs).

Material for Plates
The plates can be wood (maple, walnut or black MDF plates can be supplied by Machina Dynamica) or marble or granite of sufficient thickness (minimum 1.25 inch). Machina Dynamica does NOT provide granite or marble plates, however customers should have no difficulty obtaining such plates in their area. Machina Dynamica will provide springs and NASA grade ceramic cones in cases where customer wishes to construct Promethean(s) using marble or granite. Flagstone/bluestone is an inexpensive and effective substitute for granite/marble in constructing Promethean.


Promethean Base Isolation Stand (Solid Maple)



Promethean Base in solid 1.25 inch thick high grade maple 19x16
with 3 Super DH (Diamond Hardness) Cones and 3 Special Helical Springs.
Promethean with 3 springs isolates component up to 60 lb. $399 complete.

Promethean with birch ply plates is a less expensive version of the solid maple Promethean and incorporates 3 Special Helical Springs, 2 birch ply plates (19x16) and 3 Large DH Cones (in lieu of Super DH Cones) for mounting. Price $279 complete.


Promethean DIY Kit



DIY Promethean with Bluestone Plates & Special Helical Springs

NEW!! Promethean DIY Kit - Customer procures hardwood, Granite or Flagstone/Bluestone plates, then purchases Large or Super DH Cones and required number of Special Helical Springs to complete the DIY Promethean project. Example: Promethean with two 40-lb granite slabs 18x18 and 40 lb component requires 4 springs and set of 3 Large or Super DH Cones. Special Helical Springs $25 each ($100 total), Large DH Cones $60/set of 3 or Super DH Cones $120/set of 3. So, price of Granite DIY Promethean Kit w/ set of Super DH Cones and 4 springs is only $220; or with set of Large DH Cones and 4 springs only $160.

Promethean is an advanced, low-profile, "soft spring" technology isolation stand for tube & SS amps, preamps, DACs and CD/SACD/DVD players/transports. Promethean employs specially fabricated helical compression springs and two 19x16 maple or birch ply plates to achieve very low resonant frequencies in 4 directions. Promethean now incorporates Viscoelastic damping for the Special Helical Springs, improving dynamics and reducing distortion. The standard 19x16 Promethean with 3 Special Helical Springs capable of isolating components weighing up to 60 lb. Promethean is capable of isolating very heavy components - including very heavy amps and turntables - by employing sufficient number of helical springs and sufficiently large plates (see below).

Extra Large Prometheans can be constructed for very heavy components such as VPI, Verdier and Maplenoll turntables as well as very large amps. The customer should procure the plates for the Promethean locally, Machina Dynamica will provide the Springs and DH Cones. Extra Large Prometheans employ large dimension plates around 36x24 inches (about 1.25 inch thick) and sufficient number of Special Helical Springs to support the total load (component + top plate of Promethean). For example, a 140-lb Verdier turntable + motor are isolated on Promethean using two hardwood 36x24 plates and 8 helical springs; the lower plate of this extra-large Promethean is mounted on 3 Super DH Cones. This Extra-Large Promethean provides the best possible isolation for the heavy component - and at a reasonable cost. The plates for the X-Large Promethean should be granite, solid maple or birch ply (less expensive alternative).




Custom Extra Large Promethean Base with Granite Top Plate, Side View
Extra Large Promethean Base (dimensions 44x22) w/ granite top plate,
6 Super DH Cones & 10 Special Helical Springs. Turntable: TW Acustic Raven AC.
Tonearms: Schroder SQ & Ikeda IT 407. Cartridges: Koetsu Jade Platinum & ZYX Universe.




Custom Extra Large Promethean Base, Top View