About the Yamaha 400 series recorders
Just this Spring Yamaha unveiled their new 400 series recorders. It is their first new plastic recorder in more than twenty years. The design is very much like their 300 series. I did not notice any major structural changes upon first inspection. If not for the difference in color, I would not be able to see the difference between it and the 300 series instruments. So this raises the question, what makes the 400 series different? The answer is its material. The 400 series are made from Ecodear plastic. Yamaha states that the material is a plant based plastic made from corn starch. The starch is converted into lactic acid by means of bacterial fermentation. The acid is used as a monomer in creating polylactic acid (PLA). Such processes typically involve ring-opening polymerization using a metal catalyst such as tin octoate, or direct condenstation of the lactic acid monomer. The PLA is combined with ABS resin through an original polymer alloy process developed by Toray. Specifically Yamaha states that Ecodear is 3 parts polylactic acid and 7 parts ABS resin.
I will post an audio comparison of the 302 and 402 soprano recorders soon. My initial impression is that the 402 is very slightly quieter than the 302. Its tone is a bit more rounded and less ringing. Both of these differences make the upper register of the 402 much more usable than that of the 302. The body of the 402b does not resonate as much as the body of the 302b. I suspect that this may be caused by the density of Ecodear. With wooden instruments I have found that the resonance of the body is desirable. With the 300 series recorders it may play a role in the ringing sound that the recorders produce.
This photograph is slightly misleading. Both instruments are exactly the same length. The photo was taken at an angle with the 400 series instrument closer to the camera, and thus the 402 instrument seems to be longer than the 302 instrument.