gaze, moidy, if you would, upon your last posted circuit diagram. see! the emitter of that circuit connects to ground, or a capacitor, so will show 0V at all times. no, really, stay with me ..... also see the base connected to - no DC volts, cause of old mate "cap1" and the resistors to ground. and as for the collector, the 10nF connected to blocks DC from the opamp end, and that only leaves the input resistor/s, one of which pulls to old mate ground, and the other which connects to signal, which we all know carries no DC offset.
so. something isn't wired as your circuit shows, and is loading that transistor with all sorts of DC, turning it on and eating yer signal. switch power OFF, pull the transistor from the socket, meter with yer meter set to ohms from each socket pin to places like V+, ground, signal in resistors, the opamp pin 3, etc. then work out where the badness is. enjoy.
I think your layout has errors. the transistor appears to be one row low, the collector is connected hard-to the input, and not to the 10nF to the oppie. PERHAPS - cut that link at top of 5, and link it to D instead. I stopped looking then, there might be more.