Technical information: Using heat sinks for speaker units
Stage VD-X makes a number of speaker units using neodymium magnets. For tweeters this is a cost effective way of reaching the desired parameters, and the only way to obtain sufficient motor power and at the same time ensuring a compact and lightweight design. Neodymium tweeters are very well suited for AV applications, where the large magnetic stray field from a ferrite motor would prevent using it close to a traditional TV screen.
Today neodymium powered tweeters are almost 100%dominating the automotive market because of favorable size; Neodymium magnets are also applicable for woofers, where they offer smaller size and lower weight than ferrite magnets for the same performance in terms of efficiency and T/S parameters. Neodymium magnet woofers are for instance well suited for AV because magnetic shielding comes by design. Due to smaller size they are also preferred for automotive applications.
Using neodymium magnets for woofers and mid/woofers also offer some real benefits in terms of sound. As an example, the same woofer would have a larger voice coil inductance (Le) if fitted with a ferrite magnet structure than if using neodymium magnet. The lower Le and maybe more importantly, the lower absolute Le variation following cone movements, makes the neodymium motor powered woofer sound better.
However, there is a price to pay for using neodymium magnet!