First, a warning, it's long.
Here's my review for the two T24s I led a team to build for my Eagle Project. But first, a little background:
This T24 build was my Eagle Project. For those who don't know, the Eagle Project is one of the last few requirements towards earning the prestigious Eagle Scout rank of the Boy Scouts of America, a youth program that focuses on the leadership and character development of young men. Other requirements include an intensive board of review, 6-month troop leadership stent, and leader conference, among many others. The Eagle Scout rank is the highest award in the Boy Scouting program. It represents a culmination of the work of an entire childhood (Cub Scouting--> Boy Scouting which starts in early childhood) and the growth and maturity of a young boy that grows into a man and learns to be independent, prepared, resourceful, and a good leader, citizen, and person overall.
The Eagle Project is a big service project that is supposed to be planned and led entirely by the Eagle Scout candidate himself (me). The candidate leads a group of other youth and adults to participate in the service project. The project itself can be many things, including school supply drives, canned food drives, woodworking projects (like this one), and circumstance awareness projects, among many others. The main requirement is that the project needs to require full and intensive leadership from the Eagle Scout candidate.
My Eagle Project started with an idea. I liked building speakers, in particular Bill Fitzmaurice horn subwoofers. I was confident that I could lead a group of people to build one, because I had just finished my dual TT and had some experience in building the horn design. Summer would be the only time I could afford to spend a lot of time on my Eagle Project because of my school's rigorous International Baccalaureate program I am participating in for the last two years of high school. I was looking for non-commercial, community-centered organizations in need of new audio equipment.
As it just so happens, this opportunity sort of fell into my hands. The church that I had just joined, The Orchard Fellowship, was growing and was moving into a new borrowed venue for the Sunday service because their current venue was getting overcrowded. In the recent services they had just started a giving campaign, wanting to raise money for equipment (stage, lights, sound, etc.) that could handle the larger crowd. I asked them if they would entertain the idea of me building some speakers for them. Originally I had wanted to build a pair of dual loaded T48's or T39's for the main service. This was to be in a gymnasium, and the stage was to be set up on the longest wall. Read: massive reverberation problems. They declined the idea of me building their main subwoofers. Now that I look back, that was a wise choice, a pair of doublewide Titans would have taken a while and I probably wouldn't have been able to finish them on time for the move to the new venue. Instead, they went with 3 double eighteen loaded DAS cabinets. The double eighteens were placed in the center of the room in front of the stage in a cardioid array, with a cabinet in the center being fired backwards to cancel out reflections off the back wall.
They proposed that I could build a pair of subwoofers for the teen hangout/worship room. I proposed both T39 and T24, but T39 was too big, so they wanted a pair of T24. They wanted them to have a pole mount socket, and they wanted to split them with a TV in the middle. Mounted on top of the T24s were to be some active loudspeakers. They were 12" loaded active DAS mains, fairly heavy cabinets. I raised a safety/stability concern about the high center of gravity from a heavy speaker on top of a 5ft pole on top of thin, relatively lightweight T24, but they said it wouldn't be an issue. We resolved to build them 21" wide, which we thought would be good dimensions for stability and maneuverability. The engineering aspect of the pole mount was difficult as well. A heavy speaker swaying around on a 5ft pole puts a lot of leverage and torque on that 5" deep pole socket. The pole socket being mounted on just 1/2" BB didn't seem enough. We resolved for laminating another 1/2" of wood, making a 1" slab of wood for the pole socket to be anchored in.
I then raised a sound quality concern with the subject of pole mounting. I tried to gently steer them away from pole mounting in a respectful manner. Remember, the beneficiary representative I was working with is a professional sound guy; he works at Tennessee Concert Sound and sets up audio systems for a living. I'm a 16 year old kid and have no place telling a professional how to place speakers. So I respectfully stated my opinion and what I knew. When I mentioned the power alley, the beneficiary representative gave me a blank face and then said he didn't think it would be an issue. I decided not to pursue the subject any further, and went to modifying the plans to include a pole mount socket.
I then got the go-ahead and ordered parts and started work on my project. I had a fairly good turn-out and got the right amount of help. I was not supposed to do any of the actual building, but to supervise and instruct. I did some construction for demonstration, and taught other youth and adults some woodworking techniques and knowledge, such as kerf and how to lay a bead of PL. There were many build sessions with different volunteers each time, so I had to demonstrate each time to a new set of helpers. I made a major screw-up with the baffle in a rush and mistakenly instructed two helpers to cut a 10" diameter hole for the BP102 (it's actually 9"). Mistake made in a rush.
Luckily we had enough BB scrap to recut the baffle and do it the right way the second time. Here's the incorrectly cut one:
I was really surprised at how quickly the helpers picked up the building process. Having all the panels cut and labeled (bolded for emphasis) before you lay any PL is great planning, by the way. The sub went to together like this: measure, test fit panel, lay PL, place panel on PL, align properly, drill pilot holes on bottom of assembly, drive screws through, drill pilot holes through side of previous adjacent panel (to brace it against a previously attached panel), drive screws through, touch up PL if needed, squirt with water, clean up hands, rinse and repeat. This process goes relatively quick with some help and smart builders. The whole time music was playing on dual TT and a pair of bookshelf speakers. Seeing the dual TT really kept the builders motivated, they knew what this T24 pair would do. Also, the smell of pizza made them work faster to achieve lunch.
Some of the following pics aren't in my build thread, so I'm not cross-posting all of these.
Part of his face is whited out because I don't show any facial features at all on the internet. Maybe over the top but that's my policy. Attaching the last screws on one of the pole mounts here:
Attaching panels, that's me to the left on the ground, instructing the guy under the sawhorses:
Here they are almost finished:
I had some plaques made at the local Awards Place, I think they add a nice touch:
Finished:
They were later moved behind the curtains so they were not seen.
I wanted to look at them!Well, how do they sound?
The T24 are wired up to 5 ohms and powered by a 1000 watt Wharfedale amp. Processing is done by a DBX DriveRack PA, steep HPF at 45hz as per the plans. One thing they haven't figured out yet is limiting, which I've been warning them about since the beginning of the project, and which is certainly imperative, especially being way overpowered by the Wharfedale. How do you limit in volts with the DriveRack PA??? (not the PA Plus, just the PA) EDIT: Solved, thanks Bruce and SirNickity Sound guy said that the PA only limits in dB. This answer might be in the plans of course, but a quick Ctrl>F plans search didn't yield any results pertaining to DriveRack PA limiting. I'll look it up after finishing this long review.bassmonster wrote:My youth pastor gave them a solid road test as soon as they were set up and in position and highpassed. He put on some LeCrae (Christian rap artist) and gave em' a rip of what I estimate around 15v. After nearly popping some of the fluorescent lights out of the ceiling he turned it down and grinned, the same stupid grin I get when I crank the dual TT in my car.
They have a good smooth tone to them. There's none of the direct radiator distortion and driver noise, it's all good clean bass. They hit plenty low enough for what we're using them for. Bass drum kicks very well and the "umph" is there in all the right places. If I didn't play a lot of dubstep, DnB, and rap, I would definitely consider a herd of these for DJ work. They are relatively small and lightweight, inexpensive to build, and pack a big punch for their size. They easily keep up with the 12" mains, in fact, the church is now using only one T24 to supplement the mains, I guess two were too much? I think a doublewide T24 and a J10 or W8 would be a killer bass guitar rig as well, though not as potent as a DR250/T39 combo.
So I finished my Eagle Project, and got it officially signed by the beneficiary. Total man-hours was 235 hours, and I personally put in 62 hours myself in planning, leadership, and work. Total cost was around $600, which was what I was expecting actually. We used 5 tubes of PL, so only 2.5 tubes per sub. That's a 50% decrease from dual TT, so maybe I've learned some. Project successful, and now I'm only a couple of signatures, a conference, and a board of review away from getting my Eagle Scout rank.
Thanks to everyone who helped me in this endeavor, thanks to Bill for the great design, and thanks to Leland for carrying speaker stuff not easily available, at a good price. And of course, many thanks to the many volunteers on my Eagle Project, to those whose tools they willingly let me borrow.
Cliffs Notes: This Eagle Project was a success. The T24s sound great and the build went pretty smoothly under my leadership.
EDIT: I forgot to mention- There was no negative sound effects from pole mounting. I'm sure in a perfect split setup there would be the power alley and such, but in the configuration these subs are in, there are no noticeable drawbacks to pole mounting. Other than the difficulty in engineering and installing the pole mount, and the safety reasons of course. Given the choice again I would still decide against pole mounting. But in the church's interests, the convenience of just sticking a pole in the sub and sticking the mains on top of the sub is more practical than lugging around speaker stands in the already cramped trailers.
Thanks for tuning in to the long post, now you weary readers can finally rest your eyes.