Loudspeakers

The vast majority of loudspeakers are equipped with a dome tweeter of 25mm diameter or thereabouts for reproducing treble frequencies. The dome profile offers good directivity and, particularly when fashioned from the lightest, stiffest materials, enjoys low distortion with breakup resonances pushed out to ultrasonic frequencies. Old-school ribbon drivers, where the diaphragm was also the electrical conductor, have fallen out of favour because they are typically very fragile and require a matching transformer to isolate the amplifier from its vanishing low electrical impedance. Few amplifiers relish driving a near-shorted load...

A more realistic alternative to pure foil ribbons are 'pseudo-ribbon' drivers like Raidho's tweeter. This is an isodynamic driver with a thin polymer diaphragm carrying a flat, zig-zag shaped 'voice coil' etched from a conductive coating on one surface [see inset pic]. Raidho claims to have reduced the membrane's mass to just 20mg while enhancing the unit's waveguide, the rear panel and magnets that form the encompassing field. There's no suggestion of tantalum being employed in this latest generation of Raidho's tweeter but sensitivity is improved by a claimed 3dB and distortion reduced by a massive 35dB.