DAC digital-to-analog conversion buffer low-pass filter circuit

　　The first stage low-pass buffer uses an OPA627 single op amp integrated circuit, with a maximum frequency of 16MHZ and a conversion rate of 55V/us. All parameters are quite good. The second stage uses a dual op amp OPA2134, which is very bold. This circuit is relatively simple and convenient for beginners to make. As long as the components used are well selected, your CD player can be reborn. The negative input terminal (i.e., pin 2) of U1 can be connected to the output terminal of the DAC digital-analog decoding. These two ICs are a bit expensive. Friends with average economic conditions can choose other op amp ICs with input composed of field effect tubes, such as the mid-range OP275. For low-cost ones, you can choose LF353 or single op amp LF356 (Note: Only the NS National Semiconductor has a decent sound in the LF series, and the others are not considered). TL082 or TL072 also belong to this category, but there is no need to modify the machine here. Personally, I think at least the National Semiconductor LF353 should be used.

　　Friends who have high requirements and economic conditions can switch to AD827 or AD712. It is better to choose a higher frequency for the first stage op amp.

　　NE5532 or other op amps that do not use field effect transistors as input cannot be used in the first buffer, because high impedance input is required here, otherwise it will cause signal loss. (Also: Now I feel that the sound of 5532 is jittery and harsh, so I basically don't use it anymore)