 Also in the product line @-@ up were NS @-@ <unk> , NS @-@ 10M X , NS @-@ <unk> , NS @-@ <unk> . The NS @-@ 10M X is a " Studio " with magnetic shielding and a different tweeter . In the 1990s Yamaha introduced the NS @-@ <unk> , a bass @-@ <unk> version of the 10M X with a different tweeter and grille . Designed for home cinema , it has bass response down to 43 Hz , nominal <unk> of 6 <unk> and maximum power handling rated at 180 W. A miniature version named Natural Sound <unk> Speaker <unk> was launched in 1997 or 1998 . 
