  We analyze the scaling of the X-ray power density spectra with the mass of
the black hole on the example of Cyg X-1 and Seyfert 1 galaxy NGC 5548. We show
that the high frequency tail of the power density spectrum can be successfully
used for determination of the black hole mass. We determine the masses of the
black holes in 6 Broad Line Seyfert 1 galaxies, 5 Narrow Line Seyfert 1
galaxies and two QSOs using available power density spectra. The proposed
scaling is clearly appropriate for other Seyfert galaxies and QSOs. In all but
1 normal Seyferts the resulting luminosity to the Eddington luminosity ratio is
smaller than 0.15, with a source MCG -6-15-30 being an exception. The
applicability of the same scaling to Narrow Line Seyfert 1 is less clear and
there may be a systematic shift between the power spectra of NLS1 and S1
galaxies of the same mass, leading to underestimation of the black hole mass.
However, both the method based on variability and the method based on spectral
fitting show that those galaxies have relatively low masses and high luminosity
to the Eddington luminosity ratio, supporting the view of those objects as
analogs of galactic sources in their high/soft or very high state based on the
overall spectral shape. Bulge masses of their host galaxies are similar to
normal Seyfert galaxies so they do not follow the black hole mass-bulge mass
relation for Seyfert galaxies, being evolutionary less advanced, as suggested
by Mathur (2000). The bulge mass-black hole mass relation in our sample is
consistent with being linear, with black hole to bulge ratio $\sim$ 0.03 %,
similar to Wandel (1999) and Laor (1998, 2001) for low mass objects but
significantly shifted from the relation of Magorrian et al. (1998) and McLure &
Dunlop (2000).
