[timbley]

 I can just image how the speaker will sound like.....but nay about moving it around, right?

Right! Moving the big box is quite a chore. Fingers toes and backs must be minded at all times. I've found it pretty easy though to slide the box around with the towel underneath it.

[Bingenito]

Very nice job!

That is a great project. Most people would just pay someone to cut some MDF and route a few holes.

Besides a really dead box you know that if anyone ever breaks into your home the subwoofers will still be there when they leave.

Once you have all the concrete boxes done remove the drivers and acid wash them then spray dye on the concrete with the polymer clear coat like the way the commercial floors are finished. That would be sweet!

[timbley]

Thanks for your comments. The acid wash and clearcoat does sound like  a great idea. It'll make them look uniformly dark, and shiney. I'm also thinking about letting some kind of vine grow all over them, giving them the ivey league look.

[timbley]

Since last post I've managed to complete both concrete subwoofer enclosures and 8" driver enclosures. I landed myself in the emergency room thinking I had messed up my hip really badly trying to lift an 8" enclosure onto a subwoofer enclosure. I passed out and smacked my nose on the floor. Apparently there's nothing really wrong with my hip. I just strained a muscle deep in there and it caused me to pass out for some reason. I nearly passed out again when I saw the medical bill. Amazing how much they charge for just checking you out for a few minutes and sending you home.

Listening tests so far suggest that the bass is very nice. I like it better for sure than the bass from the RF-7s I had earlier. But it's not terribly impressive for showing off. Just nice and smooth, especially when the woofers are moved toward the center of the room.  I may have to build a coffee table subwoofer.

I've noticed that my ear isn't too picky about whether the high and low frequency drivers are near each other. I'm not being bothered by coherency problems at all even with the woofers carrying up to 1.24kHz and positioned several feet from the mids and tweets That may be due to the steep digital crossover slopes. I don't hear much difference when I apply time delays to correct for position. Positioning the dirvers for best frequency response in the room is far more important to my listening enjoyment than time coherency or precise imaging, although I'll take it all if I can get it.

The concrete is cracking at the joints where I mortared it together. I've taken to filling the cracks with glue for now. I think though that I'm going to have to start over at some point in the future. Strangely, the first box I built is the only one that hasn't shown any cracking yet! I think I used more vermiculite in that box than the later ones.

I've been experimenting with 3 and 4 way configurations. But overall I'm preferring the sound of all 5 drivers. The 8" Eton will easily push up through where I'm using the 4" driver. But the 4" sounds a little faster and clearer to me. The 4" can push down to lower frequencies too. But the 8" just sounds like it handles the lower notes more gracefully - like it's not working so hard. Similar case with the 15" woofer and the 8". Next I need to see how the Eton 4" can sound through the range where the Morel 2" is covering.
I've heard some amazing life like sound from time to time with different speaker placements and EQ settings.  Looks like I'll be experimenting with this for quite a while.

[timbley]

And I am very, very flattered!

She actually said that my 5 way speakers sounded "super clear."
That alone from her has made all the effort so far worth it.

[timbley]

After some setbacks with the digital crossovers going haywire on me, and the concrete boxes cracking, I've got the system running at a point where it pleases me every time I listen to it, with any kind of music or sound track from any kind of source. It just sounds great.

One of my biggest concerns about building a 5 way was the lack of point source coherency. To my surprise, this hasn't turned out to be a problem. And actually, there is a huge benefit in sound quality if I ignore the issue and experiment with moving the various drivers considerable distances from each other. I've got my upper midrange drivers and tweeters in-board of the lower mid-range and bass drivers by quite a distance, as can be seen in the picture. The crossover frequency at the gap is 1250 Hz! I know all the theoretical issues about point source coherency, comb filtering, and time alignment. But the truth is different with a digital crossover, especially in a small room that has acoustical problems.
I now think that one of the biggest advantages to using an active crossover with steep, 8th order slopes is that you can get away with moving the drivers away from each other.

Here's 3 ideas I have about why it's good to be able to move drivers apart.

1. The sound from each stereo channel is NOT a point source, or a line source! A perfect point source stereo speaker may be great for giving us a sense of 3D space based on loudness and timing issues alone. But it creates a serious problem for our other sense of direction: our outer ear. The point source is a dead give away for our pinnae that the sound is actually coming from two discreet points. To enjoy this sound we have to learn to ignore this obvious clue.
By spreading the drivers apart, both horizontally and vertically, we disrupt this clue, and the sound is more convincing.

2. Moving the drivers away from each other prevents early reflections off adjacent larger drivers and their enclosures.

3. Each driver can be placed in a more optimized position in the room for smooth response in it's specific frequency range.

The big worry , time alignment, seems to be a far lesser issue than it's made out to be. I can auto time align the drivers to the central listening position, and it really doesn't amount to much. Even if I'm sitting way off to the right at my computer, the sound is simply beautiful.

Now I'm contemplating having minimum baffle enclosures built for the 3 upper range drivers, with poles for stands that will allow them to be adjusted for height so I can precisely place each driver for optimum results.