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Old 09-22-2014   #26
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Default Re: Alpine Type R 12D2

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Originally Posted by BP1Fanatic View Post
I vote for a tapped horn!
LOL - I don't think that would work with these drivers. Efficiency is low, which means that it might be impossible to come up with a TH alignment that works well and can be physically realized. Plus a TH with two of them would likely be too damned big for my Car - here's an example of how much space one 40Hz TH based on a 12" driver takes up in my car's trunk:
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Old 09-22-2014   #27
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Default Re: Alpine Type R 12D2

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Originally Posted by BP1Fanatic View Post
I vote for a tapped horn!
Here's my front loaded horn with the Alpine Type S 10":

Sealed Box versus Infinite Baffle



It's big - about three cubic feet. A couple of twelves would fill up the entire cabin, unfortunately.


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Old 09-23-2014   #28
 
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Default Re: Alpine Type R 12D2

I've always wanted to Build a horn for home theater use. Maybe one of these years I'll get around to it.

How does the cat affect the tuning?

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Old 09-23-2014   #29
 
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Default Re: Alpine Type R 12D2

It doesn't have to be a positive flare TH!

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Old 09-23-2014   #30
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Default Re: Alpine Type R 12D2

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Originally Posted by 77'cj7 View Post
I've always wanted to Build a horn for home theater use. Maybe one of these years I'll get around to it.

How does the cat affect the tuning?
It's funny, I'm pretty close to trashing all of my low frequency horns.
Not 100% sure, because they work fine, but here in San Diego they're nightmarishly large.

All of this is completely subjective, so take it with a grain of salt, but here's some things I've noticed, based on running front loaded horns and tapped horns for a few years now:

1) I find that nothing improves the sound of bass more than running multiple subs. I've found that even three or four utterly cheap-ass subs sound really good once you get them dialed in. At one point I had eight subs, but I've cut that down to three. In particular, varying the height makes a huge difference.
2) The efficiency gain is real. My Alpine dual 8" Type R (Tapped Horn for the Lazy and Impatient - diyAudio), in particular, works very very well. Unfortunately, the efficiency gain is a pain in the ass! When running multiple subs you want the output to be fairly consistent. For instance, if you have three subs, you don't want one to be 10dB louder than the rest. And that's what sucks about horn subs. The gain is real, but it's also a real problem!

At the moment, the thing I'm really in love with is the ability of a front loaded horn to move the air in the room. For instance, I have a pair of horn-loaded 3" woofers that I'm using for midbasses, (Ikea Midbass Horn - diyAudio) and even at fairly low SPLs you can feel the air vibrate. This really surprised me, because I'd generally thought that the 'punch in the chest' effect came in around 60hz.

But my 3" front loaded horn only plays down to 150hz, and it gives you that effect, even on male vocals. For instance, if you're watching a movie and someone with a deep voice is speaking, you can feel the guttural impact of their voice in the room.

It's a fun effect! And it's an effect that's impossible with vented boxes, tapped horns, back loaded horns, etc.

So I'm making a bigger and badder version of that box, using a 7" woofer, instead of dual 3" woofers.



TLDR: I'm thinking about trashing my horn subs. But I'm also thinking about horn loading my speakers down to 100hz. From 20hz to 100hz I would use an array of sealed subs. All speakers would be monopoles, particularly because I get a kick out of a sub's ability to pressurize a room.

This Danley video of his front loaded horns shows how this works:


https://www.youtube.com/watch?v=rgQ-tu_mAwM


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Old 09-10-2016   #31
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Default Re: Alpine Type R 12D2

I noticed these this morning while giving the Car a thorough clean. Hairline cracks in the plastic dust-cover of one of my Alpine Type R subwoofers. One of them extends almost from the edge to the center of the cone, while the other is not so long.

What could have caused this? These subs don't really see a lot of Power - 600W each at most, and not that often either.

This is the first time I've seen something like this. I've seen cracked dust caps before, but that's usually when they're paper and they've been subjected to dry-rot. What would cause plastic to crack like that?
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Old 10-14-2016   #32
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Default Re: Alpine Type R 12D2

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Originally Posted by Brian Steele View Post
I noticed these this morning while giving the Car a thorough clean. Hairline cracks in the plastic dust-cover of one of my Alpine Type R subwoofers. One of them extends almost from the edge to the center of the cone, while the other is not so long.

What could have caused this? These subs don't really see a lot of Power - 600W each at most, and not that often either.

This is the first time I've seen something like this. I've seen cracked dust caps before, but that's usually when they're paper and they've been subjected to dry-rot. What would cause plastic to crack like that?
It's gotta be a fatigue failure, right? Flexing of the cone over and over eventually resulting in a crack? Unless you can find an impact site that instigated the crack

On this video you can see the folds in the surround which I believe indicates asymmetrical loading of the cone/surround. With the HMR surround plus a SUPER rigid cone that doesn't seem possible, but here we are. You are sure it's a crack and not a scratch, right?

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Old 10-14-2016   #33
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Default Re: Alpine Type R 12D2

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Originally Posted by 94VG30DE View Post
It's gotta be a fatigue failure, right? Flexing of the cone over and over eventually resulting in a crack? Unless you can find an impact site that instigated the crack
There are no marks on the dust cover that suggest something hit it, so it looks like fatigue. It's definitely a crack, and there are more than one of them too. The plastic dust cover seems to be quite thin, thinner than I'd have expected it to be. And more pliable too. I'm comparing them to the plastic dust covers on my old Infinity 122.7W subs, which appear to be pretty tough. H*ell, someone's shoe once fell and bounced around for awhile on one of the 122.7Ws when I had them in use, and the plastic dust cover wasn't even scratched .

I suspect that the damage may be due to ambient heat (I live in the Tropics), not from over-driving the subs. Only one appears to be damaged at the moment though.

While I'm disappointed (very much so), I wonder how much mass the dust cover is adding to the 12D2's cone? If it's quite a bit (like the old JBL 1200GTis), removing it entirely may increase Fs and reduce Qts, making the 12D2 a suitable driver for another little project I've been considering...

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Old 10-16-2016   #34
 
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Default Re: Alpine Type R 12D2

Do tell Brian....

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