This work is based on the model published in viXra:1310.0189. Because the CMBR follows the PLANCK's radiation rule more or less exactly, it should, because of the indistinguishability of individual photons, apply to a whatever black emitter. Therefrom arises the guess, that the existence of an upper cut-off frequency of the vacuum could be the cause for the decrease in the upper frequency range. Since the lower-frequent share of the curve correlates with the frequency response of an oscillating circuit with the Q-factor 1/2, it is examined, whether it succeeds to approximate the Planck curve by multiplication of the initial curve with the dynamic, time-dependent frequency response of the above mentioned model. Reason of the time-dependence is the expansion of the universe. This version considers the correction of a calculating error in viXra:1310.0189, effecting the frequency- and phase-response as well as the phase- and group delay. Furthermore, an updated value of H0 is used, based on the electron mass specified in viXra:2201.0122. Deutsche Version verfügbar in viXra:2008.0139.