Haptic simulation systems allow human users to kinesthetically interact with virtual environment models through a robotic mechanism known as a haptic interface. The range of environment dynamics that can be stably rendered in a haptic simulation system is determined by a number of factors, including the method by which the virtual environment is implemented in discrete-time domain. Uncoupled stability, the stability of the system when it is not interfaced to any user, is regarded as one of the most stringent stability conditions for impedance-type interfaces. In this work, we analytically and experimentally investigate the system uncoupled stability conditions for various discrete implementation of damper-spring environments when position or velocity is sampled. The results point at different ranges of environment dynamics suitable for various applications.