This speaker was installed in my Mackie srm450 v1. It wasn't an exact fit but the screws aligned nicely. It has a small gap around it which can be modified. A good eq can cut some of the low to low mid frequency muddiness. It's basically the same speaker with more punch. I like it for a cheaper alternative. I still have the original. This Celestion 12 inch speaker can replace my monitors which I haven't replaced yet. I'm glad this speaker can be used in the Mackie srm450 v1 since it's one of the best speakers around. It's just heavy.