Long:
Passive radiators are mainly interesting if you want to have a small chamber with a low tuning (in other words long ports). That's a typical problem for HT where you want small enclosures in your living room, that dive into (or under) the low 20's. However in PA and especially PA reflex cabinets, the chambers are large and the tuning isn't that low either.
If you factor in that a single 18" driver likes one or two 18" passive radiators, you're not only complicating the design (where to place those radiators ?), you're also increasing cost to a new level.
Over heating isn't as large as a problem apparently, as there are plenty PA cabinets that seal the driver in a small closed volume (Punisher, Lab-horn, HD15, 1850 horn, etc.) However there have been tests (Wayne Parham) that showed benefits of some additional cooling in one of these designs. I believe that when you're pushing drivers to their limit, venting can have it's benefits.
I've seen some PA designs utilising passive radiators but they always struck me as novelty items.
Short:
Passive radiators solve a problem that's not common in PA, they can complicate things, cost more and cool less.
Best regards Johan
Passive radiators are mainly interesting if you want to have a small chamber with a low tuning (in other words long ports). That's a typical problem for HT where you want small enclosures in your living room, that dive into (or under) the low 20's. However in PA and especially PA reflex cabinets, the chambers are large and the tuning isn't that low either.
If you factor in that a single 18" driver likes one or two 18" passive radiators, you're not only complicating the design (where to place those radiators ?), you're also increasing cost to a new level.
Over heating isn't as large as a problem apparently, as there are plenty PA cabinets that seal the driver in a small closed volume (Punisher, Lab-horn, HD15, 1850 horn, etc.) However there have been tests (Wayne Parham) that showed benefits of some additional cooling in one of these designs. I believe that when you're pushing drivers to their limit, venting can have it's benefits.
I've seen some PA designs utilising passive radiators but they always struck me as novelty items.
Short:
Passive radiators solve a problem that's not common in PA, they can complicate things, cost more and cool less.
Best regards Johan