Thanks again to all of the knowledgeable people who unselfishly share their knowledge and experience. I am looking at buying subs for my classic rock band PA. "Back in the day" all of the high end subs were in folded horn or other type of enclosures "tuned" to amplify lower frequencies. Now it seems that half of the high end subs are in direct radiator cabinets. The direct radiator subs would certainly be easier to transport and store, but I would not want to sacrifice a significant amount of sound quality. What are the pros and cons of sub enclosures?
You are right that (in most cases) a folded horn has a larger footprint than a typical direct radiating subwoofer. In cases where a folded horn is not larger (or is not much larger) than say a dual 18" DR sub, the folded horn is likely to be compromised and does not behave fully as a bass horn.
Back in the day (which you refer to) "we" often preferred folded horns because they provided more acoustic outut (within their passband) and (just as likely) the DR subwoofer drivers simply ran out of steam. Sometime during the late 1980's, cone drivers began to become available with greater power handling and slightly higher sensitivity. At the same time, power amps were developed with significantly greater output. So we began to introduce (or observe others who began to use) direct radiating subwoofer systems that could get as loud (or loud enough) as our folded horns had and they took up less truck, van and stage space *and* went lower. We began to experience and appreciate life below 50Hz
One of the sonic characteristics which almost all folded horns exhibited was compression. Which makes sense when you consider that sound is being squeezed into a small throat and then allowed to expand as the flare travels (expands) through the enclosure and exits via the mouth. Horn Theory 101.
When we tranistioned to DR subs, I was in love with the extended LF response (this was also when 5-string basses became a significant trend, thus response went down to 32Hz) and smaller size plus the lower load impedance to the amplifiers. But I also missed the very nice, acoustic/mechanical compression which tightened up the kick drum and bass (slapped or plucked/walking).
Over time I guess I got used to DR subs and relied more on electronic compression to get what we wanted. Alot of people did this.
There are folded horns available now which, for all intents and purposes, go as low as DR subs ....... or low enough. Tom Danley's tapped horns come immediatley to my mind. But they still have to follow the rules (laws of physics) and are larger than most dual 18" DR enclosures will be. The LAB Sub is an iteration of Danley's design philosphy and seems to work in much the same way as their tapped horns do.
It would be intersting to calculate and compare the footprint of a DR subwoofer system versus (say) one with Danley tapped horns (or other folded horn systems) where each provide the same acoustic output and low frequency limit. And also compare cost.
I believe that DR sub systems are still used more widely at all levels of the industry (including installed systems) than folded horns. But perhaps not by a huge margin. And I, for one, strongly believe that the new breeds of well-designed bass horns have their place.
In your own search for an appropriate subwoofer it is likely that a DR will suit you best. There are a lot of very good devices out there. And there's a good amount of crap. In my experience, cost is a huge factor. There simply are no (comparative) "bargains" when it comes to moving lots of air while being reliable and sounding good.
Try before you buy.
Hopefully this somewhat helps to answer your query.
