DIY Bass Traps + Acoustic Foam?

[Protools Guy]

I have Markertek 2" egg shell foam all over my walls in my studio (control room and drum room). The drum room has a very live floor (vinyl), and the control room is carpeted. Both rooms have 4" acoustic ceiling tiles.

My control room is about 12x14 and my drum room is 12x22. My ceiling is 8' in both rooms.

I'm getting ready to make some bass traps. (4" Mineral Wool)

I have 2 questions:

Should I leave the foam on the walls and then put the traps on the walls on top of the foam? (I'm planning of putting them in as many corners as possible as well).

or

Would it be a good idea to put the 2" foam on top of the bass traps so the sound goes through the foam first, THEN through the trap?

Thanks for your help!!

[Glenn Kuras]

It would be better to put the foam on top of the traps IF the traps don't have any kind of FRK facing to them. If the bass trap has a FRK facing or any kind of limp membrane to the front then don't put the foam on top of it.

Hope that helps,

Glenn