Several weeks ago I conducted tests on grades two and three Azo printing a Stouffer 21 step tablet and reading the resulting reflection densities using a 310 Xrite TR densitometer. The tests indicated that grade two Azo has a density range of 1.60 and that grade three Azo has a density range of 1.10.
I then conducted tests on FP4 (PhotoWarehouse ISO 125 film) using Pyrocat HD 2-2-100 to arrive at development times that would provide a negative of that density range. I did this by once again exposing a Stouffer 21 step tablet and the resulting transmission densities were read using the blue channel of the same densitometer.
My times for net negative density of 1.60 are as follows:
N-2 Development (9 Zones contracted to 1.60) -- 6 minutes: 15 seconds
N-1 Development (8 Zones contracted to 1.60) -- 7 minutes: 45 seconds
N Development (7 Zones to 1.60) 11 minutes: 45 seconds
N+1 Development (6 Zones to 1.60) 16 minutes: 45 seconds
N+1 1/2 Development (5.5 zones to 1.60) 27 minutes: 30 seconds
Development temperatures were 70 degrees. Film was exposed at EI 125 using incident metering. I have found that my corresponding reflective meter readings using a Zone VI modified Pentax digital meter were EI 64. The negatives were brush developed in trays.
I have just finished printing 6 negatives that had been developed with varying contrast ranges (N to N+2) and they have printed with greater ease then what I had accomplished by relying solely on DBI.
These results were accomplished using my equipment in my system and your results may vary.