Loudspeakers

While soft dome tweeters are still popular in some quarters [HFN Nov '23] most loudspeaker engineers are typically working with very light and stiff treble drivers in an effort to extend the ultrasonic response of their designs. After all, why use 'hi-res' 96kHz/DSD128 media if the speaker's response dips above 20kHz? B&W certainly pushes at the boundaries of response with its custom tweeter diaphragms. Nevertheless these 'light and stiff' domes usually have a pronounced primary breakup mode – not the case with most self-damping soft domes – that must be deferred to as high an ultrasonic frequency as possible [see inset Graph].

The choice of materials impacts directly on the achievable performance, so the costly 'Diamond' dome employed in the 801 D4 [HFN Nov '21] has a well-suppressed double resonance at 46kHz and 69kHz [black trace], while the 25mm decoupled 'Carbon' dome used in the 703 S3 [HFN Mar '23] breaks up at a slightly lower (but still very high) 49kHz, albeit at an amplitude some +12dB above the speaker's mean output [blue trace]. With less budget to play with in the 603 S3, but with a titanium ring strengthening the 25µm-thick dome, B&W's engineers have still achieved a high 35kHz primary resonance even if this is now a vigorous +15dB above the midband level [red trace]. PM