Originally Posted by Mark Seaton
Very cool to see your project plans moving forward again.
Good move. You might want to just stick to the dual woofer version that MTG90 already had worked out or switch to a pair of TD18s like lukeamdman is using. When I scanned this thread this morning I was a bit concerned with your choice of the super tall JBLs where I have to wonder if you were just too close at the front vs third row for such a tall speaker with HF, mid and woofer sections spread vertically that much.
Of course I'm laughing at the notion of a settled list of products so quickly as those of us who know you, also know that plan will alter at least 6 times in the next 2 months.
I would echo this too. Sometimes less is more. It's easier to cross a single 15" to a single CD in a 2 way, than it is to integrate 5 woofers and tweeters in a 2.5/3/4/5 way crossover. Even active. Active is easier to actually adjust or set the crossover vs aligator clips or soldering, but it's not an easy thing to integrate many drivers perfectly. Not a project you'd want to tackle first Jake. I'm close enough, and happy to help.
I'm right at the point of measuring and setting my TD15M/DNA360 two way LCR now, and happy to help share what I'm learning and what settings I am using. If you need some help cutting up boxes or whatever, happy to help too. Right now I am at a 950hz crossover, two way, between the DNA360 and the TD15. It sounds... ok. I am really hesitant to get too excited, even though I might think it sounds good, because any DIY project you have a honeymoon phase and think it sounds amazing just because it's making sound. There is more to it than that. That's also why privately I had recommend the active so much, ditch the passive crossovers all together. It will make future tweaking and upgrades so much easier. It's not unreasonable to think you might have some AVS friends over to help you measure and tweak and improve your already decent crossover settings or EQ/delay months after your project is "completed". I don't see the same thing happening if you need to pull a woofer out and solder stuff.
If you do 4 woofers, you start worry about the acoustical effects of multi woofers and the physics of waves, center to center spacing, comb filtering, and all that crazy stuff that starts to drive you nuts. Not impossible, but just more to consider. Simple is good. Start with a single, then try a double. Then if you like, add some more. You can even do it modular, make the boxes stackable so you can run it with one woofer or two, or 4... (or 16 if you get really nuts
) That is what I did. I made the JBL 2226 box so it can go under or above the tower as a MBM. That way if I decide I want to try double 15" I could do something like a 2.5 or 3 way crossover with that 4th amp, but the box is separate so if I total epic fail, no problem. I can still do 2 way with just one TD15M. My room is planned to be 36 feet long, two rows, with bar area in the back. 3 foot false wall or baffle wall. I'm 26 wide, 10 foot ceilings. I am not far off from you. Based on this single TD15M in my garage, it's enough output to cause you to run or damage your hearing. Even at 20 feet, it's totally stupid. Only the midbass you might want more, but from 200hz + there is nothing needed more. I can't really judge because I get wicked nulls and room interactions in my garage, it's concrete floor, drywall ceiling and walls, insulated heavy duty plastic single door. BAD FOR BASS, so can't judge that part yet.
Less is more. Start small, then build. If you bite off more than you can chew, or over complicate it then you will further complicate the results. I would stick with no more than 2 woofers to start and I would NOT do 18". It's not worthwhile IMO to go from 15 to 18. You run into woofer beaming sooner with that bigger woofer, and I don't see what benefit you'll gain with the bigger woofer. Even if you can cross before it's a problem, why not have the ability to run a bit higher since you would employ a proper subwoofer system anyways, which you can locate properly for great bass response. The best place to make bass isn't always the best place to locate your LCR speakers, so I think it's best to keep them separate. I would design a speaker that could reasonably cross at 60hz to 80hz, but chasing bass too low only complicates things and is not necessary in your LCR speakers. Often times a midrange and midbass woofer will sound better if you don't tax it with trying to reproduce low bass, which is another reason not to do that. I think 60hz might possibly have a benefit, but I can't see much lower than that being of good use or design if you will otherwise employ a bigtime proper subwoofer system. You certainly want flexibility with your crossover though, since you can use your crossover on your LCR to help account for room problems.
Consider a modular design. One that you can move around, try a woofer/horn/woofer design, or a woofer/woofer/horn design, even add more woofers under or on top... then you can actually decide if it's worth it to use 4 woofers, 2, or only 1. Or you can start with 1 or two and build to more later. This sounds like a really cool project.
I also mentioned to you in the text and email about starting with JBL pro stuff, and then switching that out when your DIY project was up to par and ready to beat it out. Nothing like setting a bar high and then looking to knock it down. If you go active JBL pro you can easily just make new DSP perset settings for your DIY project and use the same amps and easily switch back and forth. Just swap the preset and speaker wires. The JBL pro stuff or cinema stuff also hold a decently good resale value so unloading it won't kill you either. That would be my recommendation if you don't want to jump in cold turkey and all or nothing, or you get impatient and just need something. Of all the things you are looking at, an active JBL screen array set up like the 4722 or whatever seems to lend itself well to conversion into a monster DIY project. After I make a some more progress and I am ready you are welcome to come hear the TD15 and JBL 2226, or I can bring it down (but they are seriously like 300 pounds each). That is another reason I say modular. 2 or 4 15" woofers, a heavy ass CD, double MDF baffle and giant box... that is going to be a monster to move around. Just manage the CTC spacing if you go with separate boxes, but way worth it IMO.