what i want to do is play test tones from 20-70hz and eq out any bumps dips? whats a reasonably cost effctive product that will enable me to do this?? whats it called where do i get one? new or used
Unless you go for a 31-band EQ, you aren't going to find anything that gives you a whole lot of control over the bottom octaves. Most will only have 1 band.
So, you need to decide if that 1 band is worth the expense and your time installing/tuning.