I would like to add to my previous information.
In the formulas I have Brovira is an ammonia digest emulsion and Portriga is not. In addition, they were coated on different supports.
They are both AgCl/Br/I although Portriga appears to be a 'converted' emulsion. This would serve somewhat to substitute for the ammonia digest in Brovira in changing crystal habit.
In my work, both ammonia digest and straight emulsions with no ammonia give rather similar tone in the developed silver, but the curve shape is different and the speeds are different.