I've implemented the circuit on page 2 of
with the addition of 1K resistors across the 100uF capacitors to define ground as being midway between the power rails.
Most of the time, it works fine, but occasionally when it starts, it pulls the ground down to 1.8 volts or so above the negative power rail, and holds it there. I have multiple incarnations of this amplifier on the same power rails, and sharing a ground (by virtue of a MiniDSP board driving them), so all of them end up sharing this skewed ground. They don't work in that state.
I have not yet determined whether it's a specific amplifier that's doing this, or whether any of them can spontaneously start up in this state - it's a time consuming process, since I cannot create this fault state at will - I have to wait for it to happen.
Meanwhile, I would welcome any insights - is the design flawed? Have I got a dodgy LM1875 IC?