I heard a pair of ADS L1290 speakers this summer. I think they were the top of the line for ADS and were highly regarded in
this 1984 review.
They are 3-way speakers with two 8" woofers, a 2" dome midrange, and a ¾" dome tweeter. Crossover points said to be 500 Hz and 5,000 Hz. I think a number ADS models shared the same dome midrange and tweeter, it may have been their "claim to fame".
The owner wanted to compare them to Salk HT2-TL speakers, so he hauled them to Dennis Murphy's house. Dennis measured their frequency response, and they had a big dip in their response, more than 5 dB, at around 5,000 Hz where the mid crossed to the tweeter. I wonder if other ADS models that have the same midrange and tweeter have the same problem?
Other than that, they were pretty good.