What the others have said is true. The 690 (reg and II) share the same beryllium tweeter with the 1000 series, but do not have the beryllium midrange. The sound quality is not quite as good, esp, in the midrange, but it is still excellent; the 690s are excellent speakers that would probably be better known and appreciated, if not for the fame of their "older sibling" speakers (the 1000s) overshadowing them. If you have a chance to get a pair, grab them. They should be cheaper than the NS-1000s, making them quite a good bargain in sonic value for money terms