Originally Posted by SteveCallas
I stop checking in on this thread for a while and i miss using an air tube as a hovercraft! Wtf? Guess i’ll be buying some air tubes now!
I have 15” drivers so a 16” tube won’t work - I’m not up to date on all the details, will this one be fine?
Steve....Thanks for stopping by. The tubes are still pretty new to the BOSS world as we know it. There's only been a few of us so far that have tried them and there's still a lot of learning going on.
Having said that, the idea is to create a small sealed volume for the BOSS driver that can be pressurized easily as the cone is moving up and down. This pressure does 2 things, 1) it creates a tremendous amount of shaker force both up and down....i.e.; the area inside the ID of the inner tube times whatever pressure/vacuum is being generated and 2) that pressure/vacuum makes the cavity expand and contract easily because of the very pliable rubber side walls of the inner tube.
The combination of both of these result in tremendously more TR than the normal open baffle drivers do by themselves.
So, it depends on the ID of those 21" tubes when inflated....just make sure the ID is larger than the OD of your 15" BOSS drivers. Also, those tubes linked are for 2.75-3" wide tires. What most of us have tried so far are bicycle tires ranging from 1.5-2.125" wide. You only want the tube to raise your platform about 3/4" of an inch or so when loaded down. This makes the rubber isolators not compress as much and makes the platform more "floaty". I've found once this pressure is reached, the tubes deliver about 100% more displacement than the baseline open baffle arrangement using the baseline JBL's with 80 watts.
With those tubes linked being for wider tires, that means they will be squished even more to get to the 3/4" height. This will make them even fatter which will make its ID smaller. Just wanted to mention that as you're measuring the OD of your 15" drivers and comparing to the ID of the tubes....just make sure to account for this added squishing.
Also, since the baffle is no longer open, the BOSS drivers can be pushed with even more power providing even more displacement and TR as a result. I haven't measured just how much more displacement with higher JBL power because the displacement becomes very high, very fast and messes up the scaling on the instrumentation.
It's also worth noting, this amount of TR can be lots of fun, but can also be a bit much depending on the movie. It basically makes the BOSS platform a lot more sensitive and capable of delivering excursions which can sometime be distracting and, quite frankly, mildly painful especially when the frequencies are around 10Hz or so.
The beauty of the tubes are 1) They can be slipped under any mini-riser BOSS platform for easy experimenting 2) The pressure can be changed easily which affects how much bounce you like 3) The feeling is still very natural staying true to the BOSS roots 4) Surprisingly, no additional SPL has been noticed but I haven't measured either and 5) If you don't like the extra TR, simply remove and don't use them anymore
Personally, I've been using mine for about a month now and am still undecided. Sometimes, I love what they bring to the table, especially for action films and kick drums. But, because of the added sensitivity, they sometimes can be overpowering when the source material doesn't call for it and becomes a distraction at that point. Still trying to find a balance.
With your setup, this may be the perfect addition to your theater.
The last 4 or 5 pages of this thread have some videos that members have shared showing the "tubes as hovecraft" retrofits to their existing platforms if interested.