Reference: Fataawa Noor ‘alad-Darb – Vol.13, Page 371, No.16328
Question: Regarding [pronouncing] the takbeer in the masaajid, should one of the people make the takbeer and [the rest of] the people [follow by] making the takbeer after him?
Response: Everyone should make the takbeer by themselves, [because] there is no [such thing as a] congregational takbeer; [rather] this one should make the takbeer [by himself], and [likewise] this one should [also] make the takbeer [by himself]. [Note], the congregational takbeer has not been legislated, [rather] everyone should make the takbeer [individually] by themselves. And if his voice [unintentionally] coincides with that of his brother, then there is no harm in that. As for organising the [congregational] takbeer from the beginning through to the end – where they start and finish together, then there is no [legislated] basis for this.