Dual Ported ISO CABIso Cab History. For years guitarists, especially church musicians, who want to have great cranked guitar amp tone on stage have had two options. 1) Either mic your speaker cabinet behind the stage or 2) Use an iso cabinet. The problem is that until now the available iso cabinets have been nothing more than a speaker in a sealed box with fiberglass insulation to damped the sound pressure levels. All that changes with the introduction of the Jackson