The project was to create a compact line array using small full range drivers. The goal is to have great sound dispersion while maintaining a flat response curve that would dip into the low end spectrum while maintain a respectable high end, with no accompanying HF drivers.
I chose the AN2775 due to it having the flattest low end response of the 3 models. With the high Fs I plan on using the multiple drivers accompanied with the enclosure to gain a good low end response.
In my design the biggest obstacle to overcome was the low end response as the driver has a Fs 150Hz. To overcome this I designed a slightly curved bass reflex enclosure. Using the multiple driver setup, in a slightly curved enclosure, helped direct the back wave toward the four 2-inch ports while limiting the internal wave reflection.
In addition to the curves I added 1-inch acoustical foam on the interior to help aid in reflection and help smooth out the peaks in the lower frequency range. With all this in the rear of the speakers I have accomplished a lower frequency roll off of 61.8Hz. With the rear enclosure designed I turned to the front of speakers.
Since I had accomplished a great low end response I wanted to keep a great mid range response too. As this is a compact array I wanted to assist in wave direction to obtain a great wave dispersion. I could only come to the conclusion of using a front horn. I designed a short horn with a wide mouth to help disperse the sound.
This design gave a great flat response in the mid frequency range with a great wide dispersion pattern. I will be relying on the small drivers to produce the high frequencies. Since the enclosures are only 37 1/2-inch tall they are a little short for towers. So I will be building a 12-inch tall stand to bring the center of the speaker to around 31-inch which should be perfect for a sitting listening position.
The crossover design is a 4th Order Linear Phase HP filter. Using a 60Hz crossover point allowing the speakers to play low enough for a LF speaker to take over. I also decided to add an Impedance EQ since they are a full range driver. This, accompanied with the bass reflex enclosure, helped smooth out the low end response even more.
Click here to find out more about the AN2775.
The full design including measurements and dimensions is shown in the attached PDF.