Please pitch the tune in a lower key.

请把调门儿定低点儿。

《新英汉大辞典》

I'm going to play this song in a lower key.

我将以低音调弹奏这首歌曲。

youdao

I'm going to play this song in a lower key.

我将以低音调弹奏这首歌曲。

youdao