| 摘要 |
PURPOSE:To reduce the variance of frequency characteristics and to suppress the deterioration of response of a high band, by setting the resonance frequency within a reproducing band when a preamplifier is connected and at the same time setting the same at a level higher than an FM carrier frequency corresponding to the white peak. CONSTITUTION:A signal source 19 is provided with a voltage source 9 showing a reproduced signal of a magnetic head, an inductance 10 of a signal source, and a series resistance 11 of the inductance 10. The source 19 is fed to a preamplifier 21 consisting of an amplifier 23 converted into an IC, a feedback resistance 24 and an external capacity 20 connected between an input terminal and an earth via a shielding line 12 which connects a rotary transformer (not shown in the diagram) and the preamplifier. The capacity which decides the resonance frequency f2 when the amplifier 21 is connected is equal to the sum of a capacity Cs, an external capacity Cp and an input capacity Cl of the amplifier 21. Thus it is possible to set the resonance frequency f1 at a level lower than the conventional value. While, the frequency f2 is set at a level higher than the frequency corresponding to the white peak. |
