We synthesize CdMn7O12 and SrMn7-xFexO12 (x = 0, 0.08, and 0.5) perovskites under high pressure (6 GPa) and high temperature (1373-1573 K) conditions and investigate their structural, magnetic, dielectric, and ferroelectric properties. CdMn7O12 and SrMn7O12 are isostructural with CaMn7O12: space group R (3) over bar. (No. 148), Z = 3, and lattice parameters a = 10.45508(2) angstrom and c = 6.33131(1) angstrom for CdMn7O12 and a = 10.49807(1) angstrom and c = 6.37985(1) angstrom for SrMn7O12 at 295 K. There is a structural phase transition at 493 K in CdMn7O12 and at 404 K in SrMn7O12 to a cubic structure (space group Im (3) over bar), associated with charge ordering as found by the structural analysis and Mossbauer spectroscopy. SrMn6.5Fe0.5O12 crystallizes in space group Im (3) over bar at 295 K with a = 7.40766(2) angstrom and exhibits spin-glass magnetic properties below 34 K. There are two magnetic transitions in CdMn7O12 with the Neel temperatures T-N2 = 33 K and T-N1 = 88 K, and in SrMn7O12 with T-N2 = 63 K and T-N1 = 87 K. A field-induced transition is found in CdMn7O12 from about 65 kOe, and T-N2 = 58 K at 90 kOe. No dielectric anomalies are found at T-N1 and T-N2 at 0 Oe in both compound, but CdMn7O12 exhibits small anomalies at T-N1 and T-N2 at 90 kOe. In pyroelectric current measurements, we observe large and broad peaks around magnetic phase transition temperatures in CdMn7O12, SrMn7O12, and SrMn6.5Fe0.5O12; we assign those peaks to extrinsic effects and compare our results with previously reported results on CaMn7O12. We also discuss general tendencies of the AMn(7)O(12) perovskite family (A = Cd, Ca, Sr, and Pb).