The SM57 and SM58 microphones are based on the same cartridge design. The main difference is in the grille design. The SM58 was designed for vocal application and it uses a ball grille that acts as an effective pop filter. The SM57 was designed as an instrument microphone where a smaller grille size is preferred. In this application, pop and wind are not usually a concern. The SM57 uses an integral resonator/grille assembly, where grille is actually a part of the cartridge. These two grille designs place the diaphragm of each microphone in a different acoustical environment. The distance from the top of the grille to the diaphragm is shorter on the SM57 compared to that of the SM58. This allows for a closer miking position with a more pronounced proximity effect. The different resonator/grille assembly design of the SM57 is also responsible for its slightly higher output above 5 kHz.