Conventional wisdom dictates the top end limit for human hearing is no greater than 20kHz. Real instruments have been shown to produce leading edge transient information demanding a frequency response extended well beyond this, which is why most of our tweeters offer an enhanced frequency response, and we produce add-on SuperTweeters as an accessory. There are two mechanisms at work here. Firstly, it has been shown we can perceive frequencies well beyond the accepted 20 kHz limit, thought to be through bone conduction to a small inner ear organ called the saccule. Secondly, limiting the response to 20 kHz makes the loudspeaker behave strongly as a low pass filter, causing phase shift even in the midrange, which destroys the complex harmonic structure of instruments. This is, remember, something we are carefully trying to preserve with the Dual Concentric drive unit in the first place. So, the benefits of this technology will still be felt even if the source material is limited to 20kHz. For further information, please refer to our white paper, which you can request by getting in touch with us.