Ah, so you mean that the definite article forms "des" ("du," and so on) remain unchanged when there is an adjective front of the noun. But the partitive changes to "de" in the same situation.
Is that what you're showing me?
Let me think.
POSSESSIVE "DE"
la crinière d'un cheval
"the mane of a horse"
la crinière [de + le >] du cheval
"the mane of the horse"
la crinière [de + les >] des chevaux
"the manes of the horses"
la crinière d'un nouveau cheval
"the mane of a new horse"
la crinière [de + le >] du nouveau cheval
"the mane of the new horse"
la crinière [de + les >] des nouveaux chevaux
"the manes of the new horses"
PARTITIVE "DE"
certains [de les >] des chevaux
"some of the horses"
certains [de les >] des nouveaux chevaux
"some of the new horses"
PREPOSITIONAL"DE"
Je parle [de Ø >] de cheval. / de chevaux.
"I'm talking (about) horse. / (about) horses.
Je parle [de un >] d'un cheval particulier.
"I'm talking of a particular horse."
Je parle [de un >]d'un nouveau cheval.
"I'm talking of a new horse."
Je parle [de les >] des chevaux en général.
"I'm talking about horses in general."
Je parle [de les >] des nouveaux chevaux.
"I'm talking about the new horses."
Je parle [de + Ø >] de nouveaux chevaux.
"I'm talking about new horses."
What strikes me when I say: "Je parle de chevaux."
or "Je parle de nouveaux chevaux." is the impossibility to find any underlying article, hence the symbol Ø I use in my analyses. This is all I mean.
In the sentences above, as you can see, the presence or the absence of a fronted adjective doesn't seem to change anything, does it?