The Korf Blog

The inside story: our research,
development and opinions

2 November 2017
Prototype 8, Constrained Layer Damping II
Prototype number 8 has a ⅜ inch CLD armtube that consists of an outer 0.25mm-walled aluminium tube, a 1 mm layer of Shore A 5 silicone, and an inner tube, also with 0.25mm wall. The only difference with Prototype 7 is the silicone's hardness: A 30 for the previous one, and A 5 (a lot softer) for this one

Below is the vibrometry chart. I've left the Prototype 1 (same ⅜ inch aluminium armtube with 0.25mm walls, but with no damping applied) and Prototype 7 on the chart for comparison.
Hardness makes some difference. The main mode is more effectively dampened. The counterweight and bearing resonances are slightly higher, but it's all within the measurement tolerance. The headshell resonances are much lower, but they weren't that high to begin with.

Subjective evaluation
Surprisingly, it's a little bit better than a Shore A 30 dampened arm. Sonically, we're close to Prototype 1, but with less HF content.

Still, not likely to win any prizes. And one side of an LP is about as much as I can stand it.

Result: ★☆☆☆☆

Next week, next arm tube!
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