B1 buffer problem

Hi, i have made B1 buffer preamp and when powering it on or off i get maximum 2.3VDC reading to my right output channel. It makes a "blump" with one amp and some uglier noise with the other amp. I'm not so advanced on electronic repairs etc so maybe some smarter person can tell me what would cause such thing? Where to look for eliminating the problem?

PS Left channel measures ca 0.3V when powering on or off. Also tried batteries as power source no difference.
Here are pics of the amp


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It's not unusual for some units to make turn-on or turn-off pops. It's because the Plus & Minus DC supplies come up to voltage at different rates.

In pro audio the turn-on rule is:
source units first, then control units and finally the power amps.
the turn-off sequence is the opposite.
Hmm, the B1 design is odd, there's C2 which is 15mF and charged through a 10k:10k divider forming a time-constant of 75 seconds, which is clearly a mistake. I think C2 should be more like 15µF, not 15mF. This could account for large sustained turn on transients.

[ actually looking at NP's circuit description its clear he knows that C2 has a vast time constant, which is even odder, saying the circuit can take minutes to be working properly after switch on - I call that nutty design... (or at least straying pretty far from reason and common sense) ]
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