We opened a can of worms on this one eh?

Best of all...you are learning, and optimum results will be achieved eventually. It helps to have the speakers where you use them....but, most of this form of testing is usually done in an environment that is boundary free. Outdoors with the speakers on their back usually provides the cheapest anechoic type environment. You can hear what you are doing to the speaker..not what the speaker is doing to the room...It does take time.....

When I did some work with JBL..I remember ports having 1/16th cut from them......it simply takes experimentation...treat it like focusing a lens...if you are looking through fog...you may never achieve the desired results. In order to minimize false readings and observances...if outdoors is totally impractical...you can move the speaker to the center of the room...on it's back...(the most naturally minimized boundary area) and be able to hear better the results.

I envision a loudspeaker designer out of you yet!!!!

I ended up with a simple slot, 11.25" long, 0.75" wide, with a 4.5" shelf. Not perfect, a resonance or two, but it sounds musical, well balanced with impact, and it goes deep. I can live with it for a loooong time this way.

Probably the most fun was working on it with my 4-year-old daughter. You would think she would play with the mountain of toys in her room, but no, she decided daddy's lengths of 4" PVC sewer pipe were more fun. With the different lengths, we had daddy sewer pipe, mommy sewer pipe, baby sewer pipe, grandma, grandpa..... sewer pipe dress-up, sewer pipe tea party, and finally sewer pipe Bozo Buckets.

Thanks for the help, RBP. I'll give it a go again this summer.