In this paper, we present a new method to decompose musical spectrograms. This method transposes shift-invariant probabilistic latent component analysis (PLCA) which permits to decompose constant-Q spectrograms (with a logarithmic frequency resolution) to standard short-time Fourier transform spectrograms (with a linear frequency resolution). This makes it possible to easily use the method to reconstruct the latent signals (which can be useful for source separation).