So, I've received a few PM's about the BOSS. For everyone's benefit, wanted to include some additional build details and a drawing below about it to help anyone considering 1 or 2 of them for a test drive. Also, after the drawing, there's a few hyperlinks to some notable posts and pictures in this thread. These are provided to help those who want to learn more about BOSS technology and go directly to these golden nuggets to accelerate the learning curve and help with your own BOSS design.
, has put together a great summary of everything BOSS from this thread to date. He's also included some other goodies about power, DSP, wiring and Behringer fan mods us bass lovers can't get enough of in our constant pursuit of excellence in TR. That summary document is right here
. As always, after reading this and you have any questions, just post those in this thread accordingly.
1. The plywood is 3/4"....I wanted it to be stiff so the entire platform moves as one piece on command from the JBL's. It's also important to be thick because you don't want it flexing too much when walking on it or sitting on the couches and chairs. This low flexing also keeps the face of the drivers about 1/2" from the floor consistently for all drivers mounted to the platform even when everyone is sitting on it. Also, don't have the legs of one chair/or couch supported by different platforms, they should all be on one platform.....see the drawing below for examples of good and bad ideas for the BOSS platform.
2. Power needed is only about 80 watts per driver with the prescribed 12" JBL's (see the hyperlink below for the JBL model numbers and a list of other BOSS drivers used successfully) In an open baffle configuration like the BOSS (Baffle Open Sub Shaker), the drivers could get damaged easily by going beyond the mechanical limits of the drivers if too much power is applied. As far as amplifiers, if you need to buy a new amplifier for your BOSS, it's hard to beat the Behringer DSP amps based on dollars per watt. The DSP capability in the Behringers also allow the BOSS to be tuned once you get everything setup and want to experiment with different settings. There's also a hyperlink below in the "Notable Posts" section for Behringer DSP settings to deliver a flat power curve to your BOSS....basically boosting the frequencies below 10Hz.
3. The isolators can be any pieces of soft rubber that's 1" thick "after compression". The "after compression" is important because you want to give the drivers about 1/2" of breathing room between their faces and the floor. 1" tall rubber while everyone is sitting on the platform is best. This will give you 1" clearance between the bottom of the 3/4" plywood and the floor. With the foam face on the JBL's being 1/2" thick, this gives them 1/2" clearance between that foam face and the floor. You also want the rubber pieces to be no more than about 1-2" in diameter. The less contact with the floor the better. This is shown in a drawing below for visually oriented readers like me. A link to isolators is provided below as an example of something that has been tested and works great with a BOSS. The key is the durometer or softness of the isolator (20-40 durometer is good). Lastly, all the above guidelines are for the mini-riser BOSS shown in the picture below. For a BOSS in a traditional riser, the height of the isolators doesn't have to be 1" since the subs will be mounted normally and their faces won't be next to the floor as pictured below. If the rubber is only 1/2" high, that's OK for a full riser BOSS, as long as it's soft (20-40 durometer). Also, for those with thick carpet and padding, please note the carpet saver spacers linked below. These are highly recommended if placing your isolators directly on your thick carpeting
4. Placement of the isolators is important. They should be placed directly below the legs of the couch or chair pieces that are resting on it. This keeps the 3/4" plywood from flexing too much and not giving the drivers the breathing room they need below. Also, if there's more than 2 feet between any of the isolators after placing them relative to the chair/couch piece legs, place additional isolators between them. You don't want any more than 2' between isolators. This again is done to avoid flexing of the 3/4" plywood. An extra rubber grommet is shown in the drawing below right under the middle of the couch. This grommet is there to keep the platform from flexing.
5. Also, because the drivers need to be strategically placed on the plywood to clear structures underneath the chairs and couches, it seems most BOSS applications have the edge of the speakers visible once placing the seating pieces over them. This is easily remedied by covering the BOSS with carpet and simply cutting relief cuts in the carpet as it crests over that side of the driver. Below is a picture of what I'm talking about showing the carpet covering one of the drivers.
6. For the signal, I'm just using an LFE feed from the AVR going to the BOSS amp. The LPF for LFE setting in the AVR is set to 80Hz. I've found once you start going over 80Hz, the feeling isn't natural. Also, because the drivers are mounted upside down in some applications and right side up in other applications, try different phase settings for the BOSS (basically reverse positive and negative at the BOSS amplifier connection or at the BOSS itself). Try it both ways, in-phase and out of phase. One way will work best. You'll know it when you try reversing polarity. It's an obvious difference. So far, it seems those with drivers mounted magnet up (mini-riser BOSS) will be running in-phase and those with magnets down will be running out-of-phase (full size riser BOSS).
7. For those with mini-DSP's or Behringer amplifiers with DSP between your AVR and the BOSS platform, don't be afraid to experiment with different LPF's below 80Hz. When doing so, make sure to set your LPF for LFE in the AVR for 120Hz since you'll be using the external DSP to set the LPF below that. From my experiments, I've found your body position relative to the BOSS platform makes a big difference in what LPF to use. When sitting upright, there's a lot of pressure on our butts and it doesn't take much vibration of that pressure to become overwhelming. Some prefer a lower LPF when sitting upright for this reason. However, if you do most of your listening when reclined, running the BOSS full band using an LPF of 80Hz cradles your entire body in natural and commanding TR just like we feel in the real world without feeling overwhelming at the higher frequencies. Don't be afraid to experiment. I suggest giving each LPF setting about 30 minutes listening to your favorite bass demo material that you're familiar with before making a decision on what LPF you like best.
8. Also, for those with a mini-DSP, if you haven't checked out the BEQ thread, I highly recommend checking it out right here.
BEQ combined with your new BOSS is a match made in heaven. BEQ (Bass EQ) is basically manipulating the movie soundtrack signal to "restore" ULF that has been filtered when the movie was authored for home use. I guess they don't think our home setups can reproduce this ULF. But that's OK, us home theater enthusiasts now have the tools to restore that ULF with BEQ and also reproduce it with authority using the BOSS. The two technologies go hand-in-hand.
9. One recent BOSS add-on that's gaining popularity and for good reason is called the "tubes as hovercraft" add-on. Basically, this involves the placement of a 16" inflated bicycle tube around the perimeter of each 12" JBL. What this does is create a "flexible speaker cabinet" that compounds TR dramatically due to optimizing the "floating" element of BOSS plus the "shaker" element of BOSS. With this retrofit, the third element of BOSS "a rigid platform" needs to be optimized also. With "tubes as hovercraft", the shaker force of each JBL is multiplied exponentially. This additional force from each JBL wants to bend the BOSS platform even more. So, if planning a "tubes as hovercraft" BOSS design, follow the instructions above for isolator placement to keep the platform supported and minimize bending stresses. But, for any spans greater than 2 feet with just 1 layer of 3/4" plywood, there will also need to be physical stiffeners added at those mid-points in addition to the "1 isolator every 2 feet" rule in number 4 above. This stiffening can be accomplished by gluing and screwing double or triple layers of plywood together to make your BOSS platform more rigid. Or, actual support gussets or stringers (metal or wood) can be added to the platform to keep if from bending. Some members have accomplished this extra stiffening by simply adding more legs to their furniture pieces at those mid-spans greater than 2 feet. After adding the legs, just follow the isolator placement instructions above in number 4 (basically, place additional isolators below the extra legs). These additional legs with isolators below them will keep the platform from bending too much when using the "tubes as hovercraft" retrofit. To get an idea what the "tubes as hovercraft" add-on looks like, the last hyperlink below to Longeze's hovercouch has some pictures.
For a mini-riser BOSS, select the 2.5" hemisphere isolator (1.25" tall). For the the full size riser BOSS, select either the 1" or 1.25" hemisphere isolator depending how high you want your riser to stand above the floor. Either height will work for the full size riser BOSS, the key is to isolate the riser from the floor below. An alternative isolator has been reported as a good surrogate for the Hudson Hi Fi isolators for full size BOSS risers and also furniture BOSS applications. Please only use this alternate isolator for the full size BOSS risers or furniture BOSS applications where the height of the isolator when loaded isn't that critical. The link for those alternate isolators from Parts Express is below.
Alternate Isolator Link for full size BOSS risers and furniture BOSS applications
Carpet Saver Link for those placing your BOSS platform isolators directly on thick carpeting
BOSS Drawings and Guidelines
Notable posts for more information about BOSS technology
Below are a few hyper-links with some golden nuggets that may help with your own BOSS design.
's cantilevered BOSS and special guidelines for a cantilever design
- the BOSS commercial (a light-hearted take on what BOSS technology is all about)
- speaker parameters to focus on for BOSS driver selection....especially handy for those in Europe who don't have access to the $29 JBL 12" drivers or those who want a lower profile driver for underneath their chairs
's mini BOSS platform mounted directly to the bottom of the chair
's mini BOSS platform directly mounted to the chair backrest
- list of different BOSS configurations and benefits of each in rank order
- list of alternate BOSS drivers used to-date with great reports on BOSS performance
- Ideas and alternate designs for MEGA BOSS TR junkies who don't have to contend with WAF
's MEGA BOSS Experimental TR Sled (The Franken-BOSS)
's BOSS platform for a curved row of home theater recliners
's Behringer DSP settings for boosting frequencies below 20Hz to flatten the power curve
's Hovercouch BOSS build using the "tubes as hovercraft" add-on mentioned in number 9 above