Abstract: An arrangement for continuously determining the density of an elongated strip-shaped web of fiber sliver in the course of a spinning process in order to generate control signals for use in controlling the operation of machine elements operative for equalizing the distribution of the fiber sliver includes two of stepped rollers which together delimit, at a their nip region, a confining space for the passage of the fiber sliver web therethrough. One of the rollers is mounted on a support for rotation about a stationary axis and is driven in rotation, while the other roller is mounted on the support for free rotation about another axis which is parallel to the stationary axis and defines an imaginary plane therewith, as well as for movement along the imaginary plane against a spring force away from the one roller, so that the fiber sliver is compressed and moves the other roller to a greater or lesser degree away from the one roller as it passes through the confining space, depending on its density.