I have an experimental cabinet I had a friend build who is a cabinetmaker/contractor by profession. I did not have any particular design/woofers in mind when we did it a year ago. We just whacked together what looked proportional and what a 4x8 sheet would make per. I ended up with about a 4 cubic foot enclosure (internal). 16"x 20"x 32". I had him make up a series of front plates that could cover the 15" hole, so I could mount other size woofers for experimentation flexibilities. I recently put a Co-AX 15" speaker (Not JBL, sorry guy's) And at first had no stuffing or batting to put in. Sounded super horrible, tubby, and resonant, and the reflected echo came right out through the paper cone. I have not yet put any vents or holes or ports into the box, it is sealed. I don't know what size/type to do? Since I have not chosen a specific woofer/woofers, and it is still a "work in progress" and a test horse. I am not an experienced cabinet maker/designer. Nor do I intend to become one.
I do enjoy however, playing with speakers though, and learning...and listening for the changes brought by the different properties of design.
I have a another speaker (Infinity "Monitor" from the mid 70's, given to me free a month ago, with bad surrounds) which has impressive low bass performance, and when I took it apart, it was super-stuffed with batting material, up to the frame of the woofer and filling the entire space. So with that in mind, I obtained a free roll of fiberglass from a friend who was clearing his garage, and overstuffed my cabinet like the other was. What I heard was now a tight sound in the bass, perhaps too restricted? Not much output level in the lows and that is dissapointing, but the tone is fine. no echo blasting out the cone. But can one have too much filler? Should I take some out again? It is up to the speaker frame, filling all space
Last nite I removed the terminal bracket from the back and now the hole of about 3"x3" seems to relieve the pressure inside and the low output is seemingly greater, now quite nice and balanced. Maybe the stuffing is good all filled up. What might I expect if I were to cut into the front and either put a "slot" or perhaps one or two "tuned" tubular reflex ports? What type of ports are typically most succesful? From the looks of it, JBL finds paired tubes the best most of the time. How close to the woofer frame is advised, what is the theory on placement? What about rear venting? Pros and cons? I can't say what the resonance of the woofer/s are or will be due to not knowing the final Brand or model, I am just asking about average or typical for "most" woofers? I may just copy some typical JBL types, as they seem to know something about the subject. This is a "test horse" cabinet pair, so I don't want to make final conclusions about the design, it is a learning tool.. Thanks for any feedback, You guy's are great. By the way, since you are probably wondering what the CO-AX unit is, I purchased a set of new "on sale" Selenium 15CO1P-SLF 15 inch with 2 inch titanium compression driver blowing through a center dome of acoustically transparent mesh. They were going for $99/each, so I bit. Not up to JBL build quality, but at the price, pretty good, and now with the cabs getting tuned up, starting to sound pretty good...The Fs is 50 Hz. These may not find a final home in these cabs but is fun to play with. Later RE.