Actually, according to the definition that you used (http://www.merriam-webster.com/dictionary/cabal), there are the following two pronunciations of "cabal":
1) \kə-ˈbäl\
2) \kə-ˈbal\
The "a" phoneme of the "ˈbal" syllable of pronunciation 2 is actually defined to be identical to the first syllable "ˈba" of "balance" (http://www.merriam-webster.com/dictionary/balance); viz.:
\ˈba-lən(t)s\