Abstract: Portable Musical Instrument Amplifier with A shallow main enclosure which is shaped to house the electronics, a battery supply, and only the diaphram section of a dynamic loudspeaker, A speaker mounted normal to the two largest sides of the shallow cabinet, this side to be used as the conventional baffle, A speaker magnet which lies outside of this main enclosure due to the shallow form of the cabinet, An extension to this main enclosure cabinet which allows cabinet's internal volume to be be extended just sufficiently to surround the speaker magnet, An air passage created by the difference in cross-sectional area of the extension and the magnet it surrounds.