  We propose a novel mechanism for enhancing the primordial gravitational waves
without significantly affecting the curvature perturbations produced during
inflation. This is achieved due to non-linear sourcing of resonantly amplified
scalar field fluctuations. Our result is an explicit scale-dependent
counter-example of the famous Lyth bound, which opens up a promising
perspective of producing detectable inflationary tensor modes with low-scale
inflation and a sub-Planckian field excursion. We explicitly demonstrate the
testability of our mechanism with upcoming Cosmic Microwave Background B-mode
observations.
