A limiting factor in the reproduction of disk recordings with a modern reproducer is the tracing distortion arising from the finite size of the reproducing stylus. The sharpest groove modulation which can be reproduced is that having a radius of curvature slightly larger than the tip radius of the reproducing stylus. It is, therefore, desirable to monitor the cutting of disk records with a meter whose indication is based upon this curvature limitation, rather than with a conventional volume indicator. When using a volume indicator alone, overmodulation by as much as 20 db is possible. The theory and construction of such a curvature meter are discussed in this paper.