I am designing a small audio amp and am experiencing some weird oscillations in the first OPamp (NE5532), wich is setup as a noninverting amp. The amp is supplied with +-20V and has 100nf bypass capacitors directly at the supply-pins.
Only the inverting input pins are oscillating at 250kHz with an amplitude of 2V.
The supply is linear regulated (LM317,LM337) and has no measureable noise/ripple.
What could be the reason?
Thanks in advance
EDIT: I noticed, that the oscillation is quite intermittent. Then the smallest amount of signal on any pin will retrigger it.