jj420
Ex Member
|
For HT I would personally select the PR's as they act like ports, without port noise, plus they allow for a great deal of tuneability. 1 12" PR is sufficient for 1 10" driver, but you could use a 15" radiator to good effect, just remember not to weigh it down to start.
The not so basics of PRs are that they;
i. produce sound, often at subsonic frequencies
ii. Control the movement of the driver's cone and voicecoil
iii. control the total Q of a system through weight
iv. smooth out peaks in resistance on the driver, making them easy to power.
Its a short list, that looks simple, but when you get into it you start to realize just how easy it would be to tune the system totally wrong and get crappy sound.
Start with the PR's totally unweighted in a box around 2.5 cubes, maybe 3 if using the 15" PR. Likely if you do, the Fs of them will be around 13hz to begin with. Use your computer to run some sine sweeps in the 10-30hz range, and look to see what both the driver and the PR are doing.
If the driver is getting close to, or hitting its limits around 20hz, but the output is insufficient, then add weight to the PR in 50g increments until your driver behaves itself at the required level. On a cautionary note, theres only so much weight you can add before the efficincy of the whole system goes down, so if it seems like you add more, but nothing changes you have likely passed the maximum potential of the system. When you build the boxes, build them so that its easy to get the PR in and out, use inserts or t-nuts to keep the holes from stripping out as you will definitely be doing some tuning.
The PR will also change the power handling and resistance characteristics of your driver, too much weight and the coil will run too hot, but likely with as much sd as you have with the 15" PR, your coil will be fine. The sd is the radiating surface area and in the end determines the extra force applied to the driver as it approaches its limits, like a brake.
Anyways, your system will definitely be overdamped, or close to it because of the sd of the 15" PR. Theres nothing wrong with that, I personally prefer the overdamped characteristics. My ideal system, still on the drawing board, uses a 10" driver, with big Xmax, coupled to two 10" PRs with huge Xmax in about 2 cubes. On paper the system should, with two boxes ( 2x driver, 4x PR total in two two cube cabs) for dipole setup "should" be +/-3db from 21hz to the low pass XO frequency around 112db on about 250W/cabinet. This system is also overdamped, and could be louder, however, the point of balance for the system lies right around 250W, so the system can be turned up to maximum without fear of damaging any of the components. I have yet to build this, however, i do have a few other experiences with this alignment, both good and bad and can tell you for certain, that for HT, a PR cab is the only way to go. Seriously, nothing wrecks war of the worlds like horrible port noises in the middle of the cool explosions, same for popping coils off of backstops when T-rex goes for the truck in Jurrassic Park 1.
For HT, IMHO, you need the big output down low to be consistent as, unlike music, most movies contain track information below 20hz (well DVDs anyways). You might not be able to hear that, but you can feel it, but unless your system can really take it theres likely not too much good in trying to reproduce it. A PR system has a sharp sharp dropoff in output below the PRs Fs, almost like a rumble filter at 24db/octave allowing you to take a 10" driver right to its limits in a controlled manner without making it reproduce frequencies it really cant.
It sounds like a lot more work, but when its perfect, boy, is it perfect. IMHO its the way to go, like you couldnt tell LOL
JJ
|
Pages: 1
2 Dayton HF 10" (Read 13022 times)
