It is noted that the normalized output voltage in the case of zero head gap and zero head-to-medium spacing depends solely on the ratio of recording depth and wavelength. This property is used to estimate the actual spacing loss from a set of experimental frequency responses with varying recording current. In the experiments, a spacing of approximately 0.05 mu m is found. The ultimate response (corrected for gap, spacing, and efficiency losses) of chromium-dioxide, barium-ferrite, and metal-particle (MP) media has been determined. The scaling model also describes the dependence of the frequency response on the recording current. The Hi8 MP tape shows the best response, followed by the normal MP, the barium-ferrite media, and the CrO/sub 2/ medium. The optimal recording depth is large for the unoriented barium-ferrite media.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>