DIY equalizer based on Studer 169 (standard and mastering)

[soulsonic]

Also somebody please help me understand the function of U1 In this circuit. Since the possitive power is connected to 7 instead of 8

U1 is a single channel opamp, that's why power connects to 7 instead of 8. That's the standard pinout for single opamps. Pins 1 & 8 are typically for connecting a compensation cap, such as is done here. All the opamps in this design are singles.

Functionally, U1 is wired as a balanced line receiver.

 

[soulsonic]

U1 is a single channel opamp, that's why power connects to 7 instead of 8. That's the standard pinout for single opamps. Pins 1 & 8 are typically for connecting a compensation cap, such as is done here. All the opamps in this design are singles.

Functionally, U1 is wired as a balanced line receiver.

I mean to say... the opamps in the most recently posted schematic, which seems to be for the 500 series version, uses all single opamps, with U1 being the line in receiver. But if you're talking about the older original schematic, it uses a 5532 dual opamp, but U1 is still a 5534 single - and its function is the tone control amp thing whatever I don't know the right term.