|I have a large block (19" x 16" x 21/2") of high density polypropylene (PP), which I plan to use to make a base for a turntable I'm building. It must weigh 30-40 lbs based on feel. I found the following on the web regarding PP:|
Polypropylene's "natural harmonic" is at a very low frequency of 125 to 150 Hz. The normal "problem hearing range" is 1,000 to 3,000 Hz. Therefore, the material's natural harmonic is far below the "problem hearing range." The nature of sound is that the lower the frequency, the greater amount of energy is required for the sound to be heard. To quantify the difference, the amount of energy required for a 50-Hz noise to be noticed is 1 million times that required for a 3000-Hz noise.
Based on this information (from a manufacturer of boats who uses PP materials in construction), I think PP may be a very good material to use for a turntable base. It is a viscoelastic thermoplastic polymer, and should thus have good sound absorption properties. Has anyone here ever experimented with PP? I see a lot of acrylic turntable bases and platters, but none from PP. Why?