Thanks! But how about the woofer side of the sub, can it be close to a cabinet, with a distance of like 3-4cm for instance?
The side of the cabinet with the side driver is designed to be optimally placed 2-4" from the wall, preferably in a good solid corner of the room. For most rooms, I usually recommend first locating the DXD in the closest solid corner to your primary listening position. So, if the closest solid corner (no nearby openings like an open door) is in the back of the room, try it there first.
Every room is different and needs some experimentation with subwoofer placement. But, after measuring literally hundreds of studios and rooms with very sophisticated TIME DOMAIN measurement equipment with the world's best laboratory measurement microphones, and my own proprietary analysis technique (which measures and computes very much like our ear/brain mechanism interprets the spectrum of sound energy over time including and especially transients), the closest solid corner has the best chance of giving you the best and most accurate "out-of-the-box" results, in my humble opinion and experience.
The DXD's are specifically designed for corner placement which normally will give you the least room mode problems, especially if you are using the stacked DUO configuration which is technically a whole new subwoofer for a host of technical reasons.
Here is what I just wrote in another Home Theater Shack thread about this:
"Yes, a DUO will be AUDIOPHILE BASS NIRVANA for you, I guarantee it! As good as single DXD-808's and DXD-12012's are, it is a whole new experience in the DUO configuration because they are technically a whole new type of subwoofer from the single cabinets, I designed it that way.
Once you stack at least one pair, you have my full BALANCED 3D HIGH VELOCITY PUSH-PULL-PULSAR DEEP BASS PRESSURE WAVEFRONT LINE ARRAY NEARFIELD technology operating in all its glory!!!"
The DXD's can be placed anywhere in a room, but optimum performance in most rooms will be achieved in a corner placement, again, I designed it that way for all the good reasons.
Also worth noting, the DXD's performance secret (please don't tell my competition this secret) is they are very specifically and deliberately and scientifically designed to give optimum bass performance in a real room or studio with real walls, not in a parking lot outdoors where a lot of review measurements are made for subwoofer comparisons. The same holds true for close-up type measurements where only part of a DXD's output is actually measured.
The DXD's put out a sound pressure wave in multiple directions and cannot be properly measured outdoors or close-up, this is a big mistake some reviewers are making. It is somewhat analogous to trying to measure the horsepower on the ground of an ALL WHEEL DRIVE vehicle with a dynamometer, but only measuring the horsepower at one wheel.
I actually get a big kick at the outdoor and close-up review measurements which show the DXD's appearing to have unusual output levels and response, and then when a reviewer listens and measures in a room they usually comment they cannot believe how much pants flappy energy and impact is heard and felt in their real listening room with real walls and how low the DXD's measure in the room. Remember (another top secret not to tell my competitors), I don't use high pass protection filters in my subs (they ruin the bass impact) so they will go all the way down in a real room with real walls.
My mentor, Dr. Lester M. Field, used to say "the device is the perfect analog of itself!"
GOOD SOUND AND GOOD BASS TO YOU...ALWAYS...KEN