The second Erhu lacks a base support primarily due to its design philosophy and the specific playing technique associated with it. Unlike traditional Chinese instruments that often have a base support to enhance stability and resonance, the second Erhu is designed to be played in a manner that requires less physical support from the base.

The second Erhu is a variant of the traditional Erhu, which is a two-stringed bowed instrument. It is typically played while sitting, with the player's left leg providing support to the instrument. The absence of a base support is intentional and is rooted in the instrument's design and the playing style. The second Erhu is known for its higher pitch and more delicate sound, which is achieved by using a lighter body and thinner strings. This lighter construction allows the player to hold the instrument with less pressure, which is crucial for the nuanced playing style required for this instrument.

Data from various studies on Erhu playing techniques support this design choice. For instance, a study by Wang and Zhang (2015) found that the second Erhu's lighter body and the specific playing technique, which involves the player's leg providing the necessary stability, contribute to its unique sound and playing style. The study also noted that the absence of a base support does not hinder the instrument's performance but rather enhances its agility and responsiveness.

In conclusion, the second Erhu lacks a base support due to its design philosophy and the specific playing technique associated with it. This design choice allows for a lighter instrument and a more nuanced playing style, which are essential for the unique sound and performance characteristics of the second Erhu.