LA-light compressor power supply query

[slacker]

I'm thinking of building the LA-light compressor but I can't figure out whether the newest version uses a bipolar or single supply.
Here's the schematic http://aronnelson.com/gallery/johan/LA_Light_last_one_001.
I'm a bit confused because the 2 10k resistors and the opamp look like a buffered vref like you'd get with a single supply. However there's also a ground connection on the schematic just below the "compensation" cap, which if it was a single supply would be shorting the vref to ground.
Is this connection a mistake or have I misunderstood the schematic?

[Thomas P.]

you could create a vref with an opamp like this since the opamp tries to make the voltage between the inverting and the non-inverting input zero. If you would hook it up with a single supply (9V e.g) you get 4.5V at the inverting input (=> output). In this case the voltage at the non-inverting input is 0V you get the sam at the output => bipolar supply

[slacker]

yeah I thought that but if it was bipolar you wouldn't need the 1/2 supply vref you'd just have + volts and - volts and ground.

[Thomas P.]

yeah I thought that but if it was bipolar you wouldn't need the 1/2 supply vref you'd just have + volts and - volts and ground.

just because vref = 0V doesn't mean creating it this way isn't rewarding, just think of it as "some voltage" who happens to be 0V

or in another sense why would you create 4.5V this way while you could do it with just two resistors...

[slacker]

I appreciate what you're saying but why would you bother to create a nice buffered 0volts and then connect it to real ground, thats the bit I don't understand.