1 DCBirdMan 5 months ago Well here's a GK amp I made .. it was never sold like this. The GK MB 200 head (4 ohms) into the GK MBX 112 cab (8 ohm) that was only intended to be a an extension cab for the GK MB 150.Put casters, should strap, and reverb on cause I use to for guitar sometimes also. Still weighs less than the MB 150. The grille is off right now, seen off to the side in one pix. Sounded good but not too loud because of impedance mismatch. So I got an Eminence 4 ohm bass speaker and the volume is back but it just doesn't sound all that great . Of course this is really too small for a single 12 bass cab and it's just a metal box. But aren't all bass cabs over a certain rating supposed to have a port somewhere to let air out? I have already drilled holes all over this for attaching casters, head, ac outlet. Would it sound any better if put a big port hole (like 2" dia) in the back?