Vandersteen 3A Sig listening window

The owners manual states that the "6 inch high optimum listening window is centered at 35 inches when the speaker is vertical". Now is that 35 inches off the ground or 35 inches off the bottom front of the speaker cabinet? The reason I ask is because the tip toes add an additional 1.5 inches to the height of the speakers when installed. What I'm looking at can I measure 13 inches off the top of the cabinet and use a laser pointer to mark the exact point of my listening postion?
Measure from the floor. I have 5A's and you use the same measurements
Thank you for the responce. I used your advise and measured from the ground up then put a square on top of the 3A's and attached a laser pointer to the square to get an exact height for my listening postion. Wow was that a lot of adjustment to get it that exact. But the time was well worth the effort, now I have a sound stage as large as the recording will permit. I Love These Speakers
Vandys are funny that way. I always had the tilt-back correct on my 1Cs (with a pair of 2Wqs), but I read somewhere that one should also level the speaker out from side-to-side. Since my basement floor is uneven, the speakers were leaning to one side a bit. After I leveled them out, while still retaining the correct angle of tilt-back, the sound stage expanded noticeably in both hieght and width. The 1Cs now do a better dissappearing act than before, and the improvement was quick and free to accomplish.
You should love those speakers, try adding a sub in time and you will be a super happy camper.
I added a pair of Vandersteen 2WQ subs to mine and was ASTONISHED at the difference it made. Not because of the deep bass it added, but because the 3A Sigs themselves sounded SO MUCH BETTER since they (and my Quicksilver V4 tube monoblocks) no longer had to worry about making deep bass. Borrow one or two 2WQ from your dealer and give it a try. You'll be amazed and he'll make a sale.

PS Even my tone deaf wife heard a big improvement over the already excellent 3A Signatures.
I would say 2 subs is best but go one at a time if money is an issue, I know 1 is not ideal.