Zorch's build progress

So this is measured from the copper side, with a ±9 V supply? If so, the voltages look ok, except for the negative supply to the 3340 which is wrong – it’s connected to the negative rail via a resistor and should be held near −7.2 by a zener in the 3340. See:

What resistor are you using between pin 3 and the negative rail? For 9 V, the ideal value would be 200-220 ohm, so if you’re using 620 ohm you might simply be starving the circuit. Try soldering in a 330 ohm in parallel with the 620 ohm, or simply replace it with a 220 ohm resistor. (And don’t forget to remove/replace it if you decide to use 12 V instead).

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