Here's the math
I have now managed the time to listen a bit since installing Jason's RaceSpikes (TM?). I used 8 rather than 4 and have not yet played with tilt. The spikes did seem to improve image and soundstage height which is why I bought them. Midbass was tightened (a good thing) and low bass was slightly diminished. I plan to play with tilt at some point and will also play with the bass settings on my Summits. This leaves a narrow sweet spot as my major remaining ***** about the Summits relative to my previous reference Apogee Divas. Does changing the panel angle affect the size of he sweet spot? What is the easiest way to measure the panel angle and ensure they are equal (for math dummies like me)?
Hi Tony,
I explained this to Jason in a previous post on this thread but I'll try to do a better job this time. You will need a "scientific" calculator (one that has sine, cosine, tangent buttons) to figure this out.
It's called the good old pythagoreum theorum and you use it to figure all distances and angles for a triangle that contains a 90 degree angle. Anyway, here's the drill.
You'll need two pieces of string that are weighted at the bottom. For my measurement, I tied a large bolt to the end of each string. When the string hangs down and stops moving, the string line is perpindicular, or 90 degrees from the floor or whatever you attach it to.
Tape the string to the top front corner of each panel. For the left speaker, tape to the outside left corner. For the right speaker, the outside right corner. The bottom of the string, with the weight attached, should hang so it's just above the floor and allowed to move freely.
Look at each string and, if the tilt angle is exactly the same, you should be able to measure the same "offset" horizontal distance from the string to the front of the panel. Measure the horizontal offset distance, at the bottom of the woofer module, from the string line to the front of the panel. Let's call that dimension "x". Now measure the vertical distance from the bottom of the woofer module to the top of the panel where you've attached the string. Let's call that dimension "y". Divide "x" by "y" and hit the tan -1 (may be called "arctan" on some calculators) on your calculator. That result is the tilt angle, from 90 degrees, for the panel.
Before doing the division described above, you must first convert inches to its "decimal" equivalent. Say the "x" dimension is 2-5/8". Divide 5 by 8 and add 2. Repeat the same conversion for the "y".
You should also be able to see any significant difference in the tilt angle by looking at each string to see if horizontal offset distance is the same for both speakers.
So now you've done the math, converting the inches measurement into its decimal equivalent. After you divide "x" by "y", lets say you get 0.0281. Hit the cotan button and you'll get 1.609.
That's 1.609 degrees of tilt from 90 degrees. Add 90 to the 1.609 and you have a tilt angle of approximately 91 and 1/2 degrees.
This replicates what I measured with my speakers. The only exception was that I measured the dimensions from the top of the panel to the "top" of the woofer module. So in my case, the "x" dimension was 1-1/4" and the "y" dimension was 44-1/2". The corresponding decimal equivalents are, respectively, 1.25 and 44.5. Yup, dividing 1.25 by 44.5 gives you 0.0281. The arctan is 1.609.
So there you have it. I hope I explained this adequately and if I went overboard, there is no intention, on my part, to offend anyone's intelligence.
Have fun.
GG
