I dont know yet, all I can say is I got a lot of recommendations for one. I ordered one but it's not here yet. Its popular with double bass and 5 string players. Supposed to clean up those farty, flabby, rattling notes.Interesting. I noticed that the worst problem I seem to have with my Rumble is my open E and a few of the other lower notes, until I hit the A. The HPF could be a great cure for that?
High Pass Filter (HPF) and Low Pass Filter (LPF) Mega Thread