A compact speaker is enabled to mount into panels made with either of two different sized standard mounting cutout patterns, e.g. Japanese JIS or the larger European DIN, providing the small JIS overall basket diameter along with an unusually large effective cone "air piston" diameter with full excursion for enhanced low frequency response. For mounting to a JIS-configured panel, an annular adaptor ring is configured with an array of four mounting screw clearance holes in a JIS pattern by which the ring is attached to the panel, and four threaded holes on a larger circle by which the basket is then attached to the ring by relatively small sized machine screws. For mounting to a DIN-configured panel, the adaptor ring is not used: the plastic basket is configured with four extending ears providing clearance mounting holes at DIN mounting locations for self-tapping screws by which the speaker is mounted to the DIN-type panel. The ears are made such that for JIS mounting, where they are not used, they can be snapped off and removed to avoid interference with close surroundings.