Loudspeakers

Seasoned enthusiasts who remember Apogee’s iconic Scintilla ribbon loudspeaker [HFN Sep ’85] will ‘spot the difference’ between the former’s thin foil diaphragm, with horizontal slits and coplanar bar magnets, and Piega’s mid/treble ‘ribbons’. The former displayed all the properties of a true ribbon – a low moving mass driven uniformly across its surface but with a fragile, pure foil diaphragm that presented the partnering amplifier with a devastatingly low impedance to drive. And all, I might add, for an equally low sensitivity. In practice, pure ribbons are most suitable in tweeter applications, though they will still need a coupling transformer for the amplifier to ‘see’ a driveable load.

Piega’s new C112+ coaxial ribbon is, in fact, a planar magnetic or isodynamic driver, its lightweight polymer film supporting an aluminium foil ‘voice coil’ on the front surface with bar magnets distributed behind. This etched thin-film has a higher resistance than a pure ribbon, so is easier to drive, and the diaphragm is more tolerant of abuse despite still boasting a very low moving mass. However, the suspension and clamping of the planar magnetic film is always key in achieving a linear action while controlling myriad breakup modes across its surface [seePM's Lab Report]. However, Piega’s flat coaxial mid/treble driver does promise to best the off-axis response of a conventional, separate tweeter/midrange layout while also avoiding the horn loading anomalies faced by more traditional ‘dual concentric’ tweeter and cone bass/mid driver solutions. PM