A pair of similar, although slightly different high-pitched ringing noises, two new crucibles arrived in the mail for me, the nickel-plated ones I think and they are of very slightly different sizes, nominally the same, but different enough to give off two different tones, like a pair of tuning forks.
Still haven't got my solid nickel one thats meant to be on its way though, and still waiting for my carbon electrodes.