Switching field distribution and A.C. bias recording parameters

A set of tapes has been prepared for audio recording measurements by mixing cobalt modified iron oxides for equal coercivity and remanence but varying switching field distribution (SFD). At low level recording the optimum high frequency bias current but not the maximum signal level was found to decrease with increasing SFD. The long wavelength output at 5% third harmonic distortion remains unchanged. The decrease of short wavelength saturated signal with increasing SFD was separated into demagnetization and bias current losses.