12" FRFR speaker for my regular guitar cab + Helix Stomp in Helix Posted August 22 I think it would be a lot simpler to just get a decent powered speaker. I'm not sure what you're trying to accomplish by putting a full range speaker in a guitar cab. I mean, it will extend the high frequency range of the cab but it certainly will not have a flat response. As a guitar cabinet, it is designed to accentuate certain portions of the frequency band. This approach is anathema to the requirements of Full Range, Flat Response.