In mtmconvol and wavelet an angle of 0 of any fourier-coefficient means a peak of an oscillation in the data, and an angle of pi/-pi will always mean the trough of an oscillation (wavelet wise angle = 0 is implemented as cosine at peak, and sine in up-going flank)

In mtmfft each Fourier-coefficient is phase-shifted such that the angle is from the perspective of the oscillation in the data being at its peak at time = 0. This means that when computing Fourier-coefficients, the (possibly variable) onset of each trial is taken into account.