I have owned a pair of amt monitors for 24 years and have just recently had the 12 inch bass and 12 inch passives serviced because of rot. I cetainly cant say mine have ever been short of base..My model has the passive beneath the bass driver..I am looking where to buy a spare of diaphrams in case the original fail..ESS just ignore my requests for info and they never answer the phonesteve
Wellington
New Zealand