Add an IF to an arrayformula in Google Sheets

I have a simple one that is driving me nuts. I have a long list of NPS scores and I need to create a new column and add the following formula. It works great if I drag to the bottom but I can't always do that and need to to be added using an arrayformula but I'm pulling out what hair I have left trying to make it work :(

=if(A3<=6,"Detractor",if(A3>=9,"Promoter","Neutral"))