High quality preamplifier

The circuit is shown in Figure 3-10. This is a preamplifier with multi-function inputs , including tuner input, tape
playback input, ∞ phono input and electromagnetic phono equalization input. The entire input amplifier uses an integrated dual
op amp LT1057 as the input amplification function. 1/21C is dedicated to the electromagnetic phono input equalization circuit, and the remaining 1/21C is used as
a multi-function input circuit. The selection switch SAt is used to select different inputs. Includes equalized and amplified record input
. The key is used to select tape playback and recording monitoring.
    LT1057 dual operational amplifier is a high-speed precision operational amplifier with junction field effect transistor as differential input stage . Its conversion rate is
13V/,ls, and the input noise voltage is 2.lpLVn,o. It can use LT1058, LT1037, LT1028, or NE5532
etc.,