Using A1"s preamp and volume control original circuit, it has the inherent advantages of easy assembly, good impedance matching and smooth sound quality. In terms of sound performance, it can broaden the sound field, increase dynamics, and enhance resolution. You can also change different dual op amps to adjust the sound trend according to your own preferences.

Most dual op amps can be used directly and can be directly exchanged for AD827N, OPA2604AP, OPA2132PA.

This circuit is divided into two stages, the first stage is responsible for buffering, and the second stage is used as feedback volume control

(Each op amp is responsible for one channel). Its characteristic is that the input impedance does not occur when the volume is adjusted

Variety.

The music fax A1 front-end line is very simple and good sound. The good sound lies in the negative feedback adjustment, but the potentiometer of the original A1 line to adjust the volume is in the feedback loop and acts as a feedback amplifier resistor, adjusting the gain to adjust the volume, but there is a feature The volume can"t be turned off, but the volume is still adjusted to the minimum.

Note: The coupling capacitor uses 100V1UF/105.

Working voltage: dual AC AC12V~18V, dual 12V transformer is recommended

Finished board size: 70*40*25=length*width*height (unit MM)

Net weight: 40g (within 5g error)

1 x NE5532 Version Tone Board