Okay, let me try to put this into better perspective so everyone will understand how this works a little better.
Lets say you have a pair of small speakers (A/V-1's) and you set those speakers out on stands about 3 feet from the rear wall.
Sound is three dimensional and has a deep sound stage. Imaging is good.
Why? Differences in time arrival from what you hear on axis verses what you hear off axis (reflected) is part of it. No time delay shifts in the on axis response is a biggy too. Plus, arrival time of the left speaker verses the right speaker.
The stand mounted speaker will have an adjusted response that elevates the output below about 700Hz and down since it looses output level due to baffle step loss.
This is where the lower frequency waves begin to wrap around the enclosure and play three dimensionally instead of just from the speaker forward. When that happens it looses output.
Where this begins to take place is directly related to the width of the front baffle. The wider the baffle the lower in frequency the waves must be to wrap around it.
And technically to compensate for this the lower end is not boosted as it can not be passively boosted. All other frequencies ranges are simply brought down to the level of the lows to make a flat response. This is baffle step compensation.
Now I told you that story so I could tell you another story.
Back to those stand mounted A/V-1 that are three feet out from the rear walls and images so well.
Now let's slide them back against the wall.
Yea, the port is now firing right up against the wall and that would suck, but aside from that, the output that has wavelengths that are wider than the front baffle will wrap around the baffle and reflect off the wall and arrive to use along with the on axis response in the form of a slight time delay that just tends to smear the music just a little.
Imaging is now much more two dimensional and sounding as if it is coming from the wall forward.
Many of you guys have tried this before. I know you get it.
Lower frequencies are now also much stronger than they should be because there now is no baffle step loss or loss of output level in the bottom end. It all reflected forward.
Bass response is now much greater.
Mounting a speaker to a wall has the same effect.
This is not ideal for a rear surround speaker especially if you sit very close to it.
Ideally the rear surrounds should be stand mounted also and well away from side walls, plus about twice the distance away from you as the front speakers or at least no closer to you than that.
This set up can not be attained in most rooms.
So speakers are mounted in walls and on walls.
The dipole design tries to eliminate this pin point two dimensional sound by firing part of the output forward and part of it backward in a way that cancels some of the on axis output and allows you to hear reflected sound from the front of the room and reflected sound from the back of the room.
This does away with the point source sound and scatters the sound around a bit. This is just like flipping the polarity of one speaker opposite of the other speaker and sitting in the middle. You get no center focused sound but you do clearly hear reflected sound from the side walls. It's airy and adds space, but is artificial and not accurate.
Many do like it though.
The A/V-1RS fires a complete and accurate output up to the ceiling and out into the room.
With it 16" from the ceiling the response time of the output level reaching the ceiling and back again to speaker level is already a distance of 32".
It is kind of like having it 3' out from the wall. Depending on the room it can create a much greater sense of depth than other options.
Electrical time delays can be added from front to rear to delay the rear signal from the front signal but this does not add distance from the speaker to the ear to allow for a fuller propagation.
It is kind of like thinking that digitally delaying a signal to bookshelf mounted front speakers will create a three dimensional sound stage. It just won't happen. It will still sound two dimensional.
The sound of the A/V-1RS is big, airy, and sounds as if it is coming from a greater distance than the ceiling or walls.
Reflected energy is allowed for in the design and is part of the design.
See actual output if turned toward the mic from 39" away and measured with a gated time window (no reflections).
Now compare this with the measure reflected output that is un-gated. Un-gated means no time restricted view. So the response looks a little choppy and you have to consider the average.
The output level here has also been adjusted from the one above to allow for and adjust for the reflected energy from the wall it is mounter to, but the level in the bottom end and the top end is the same.
Note how the higher frequencies must be allowed to have more output to equal or be closer to an equal output level to the bottom end after the wall and ceiling reflection.
There is no adjustment to the upper levels to compensate for baffle step loss because there is none. There is still some gain in the bottom end due to the reflections.
Also note that the measured output level according to the lines on the chart do not represent any actual 1 watt/1 meter output level in the lower curve so disregard that. It was shoot from further away.
Actual output level when adjusting to a 1 watt/1 meter reference is 90.5 to 91db. This will equal the output level of a pair of A/V-3's playing up front without adjusting levels.
The sound is something that I am proud of. It's is a big step up from typical wall mounted surround speakers IMO.
Great Design Danny, How would ceiling height affect response, is there a limit? My ceiling height is 14 feet. Also hurry up and finish the sub can't wait to purchase.
Good question.
Yes, ceiling height will effect the response. Comb filtering effects and cancelations are time arrival effects.
The response is adjusted for as near flat as possible at the 16" distance.
Move it a little further away or closer up and any cancellations that occur will shift to a slightly lower or slightly higher frequency.
We're talking about a few db this way or that way in a given area.
If the ceiling is a long way away (like 6 feet away) then several waves will have propagated several times long before it reaches the ceiling and back. The response will be very much like it would be if it were on a stand behind you and it were 16 feet away.
Talk about your added delay time... This might be even better.
It might also take out a little bit of the bottom end strength and making it more balanced over all.
And those subs should be here by the 15th of July.
How do they sound as surrounds on a DVD movie with a dynamic surround track ?
These things sounded great and little different from a stand mounted A/V-1. Dynamic tracks are no problem.
Shouldn't tonality and dynamics be the ~same as the regular A/V1's?
Yes, very much so. A lot like an A/V-1 that is out in the middle of a room. Just with a higher output level.
Keep in mind that the added time delay from the sound reflecting off the ceiling and down to you is like moving a rear stand mounted speaker about 5 feet or more further back than your rear wall.
Now does the up-firing speaker improve the off axis response?
Reflected energy is more controlled rather than a more room dependant response that you might get from a stand mounted speaker. It will sound almost exactly the same mounted 16" from your ceiling as it does mounted 16" from my ceiling.
Steeper acoustic slopes also insure that off axis response is the same or more closely the same regardless of seating position. In other words less cancellation from woofer to tweeter as one is physically further away than the other when you move from one side of the room to the other.
Also the response is accurate or more accurately reflects the signal that was sent to it verses a dipole design.
Now that I have explained it in such detail I wonder how many other manufacturers will come out with something just like it in the near future?
