The Korf Blog

The inside story: our research, development and opinions

9 May 2017
Armtube with Constrained Layer Damping
Ten years ago, "Constrained Layer Damping" (CLD) was the thing in high-end audio. We saw CLD turntable plinths, CLD shelves, CLD racks, CLD aftermarket feet, CLD audio cables… I am sure if I looked hard enough I would have found CLD remote controls and power cables.

Let's see what CLD really is.
Wikipedia is unusually curt on the subject, so I will link to an explanation by the acoustic treatments supplier Vibratec. Basically, it says that efficiency of a viscous damping layer can be increased by "sandwiching" it between 2 solid layers. These layers constrain the movement of a damping layer in such a way that unwanted energy is disposed through shear rather than bending.

Illustration from Vibratec site

The advantages of CLD include low weight and high efficiency in damping of bending modes. Theoretically, this is exactly what we need in an armtube! As far as I know, no-one used it before, probably because it wasn't technologically feasible.
A well-known silicone specialist company in the Far East was kind enough to make us a set of armtube samples with a viscous silicone layer constrained between inner and outer thin-wall aluminium tubes. They have supplied us with 2 different types of viscous layer, with 5 Shore A (softer) and 30 Shore A (harder) silicones.
Can't wait to measure and hear these CLD armtubes! Would be very interesting to see how exactly they are different from the normal solid ones, and how CLD effect is different from using an armtube made of well-dampened material like wood.
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