A minor AR-18/18s information supplement/correction! The tweeter placement change, from offset to centred, was seen in the transition from the AR-18 to the AR-18s. Also, the capacitor value changed: 6 uF for the 18, 5 uF for the 18s. The 18s used the 200038-0 tweeter (featuring S-shaped leadouts for "added protection during peak power surges"), the 18 had the 200014-3 (also seen in the AR-7x). Incidentally, having both UK and USA assembled models of the AR-18s, I was surprised to see a difference in the cabinet width: USA made are 255 mm wide, UK are 244 mm. The AR-18s remains a 'cult classic', here in the UK, and is still much sought-after for use as a near-field studio monitor, by those 'in the know'. Robert_S