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Old 8th July 2010, 03:24 PM   #61
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Originally Posted by Oklahoma Wolf View Post
Yeah, I've seen it used in a design or two. The obstacle there is getting them across the border and the associated customs and duty fees, as well as some previous bad experiences with buying MCM. I'll probably stick to CSS - they're nice people and I haven't spent much money there yet.

Mach 5 has a new 12" woofer coming out soon... I'm hoping and praying it will do well in a tapped horn. It looks like a monster, and Mach 5 is both close to me and a great company to buy from.
I should post some pics of what I did to my poor Trio8 woofers

I was trying to get them to work in a small tapped horn, and cut out the dustcap hoping it would lower QMS (and QTS.)

Unfortunately, it barely made a difference, and ruined the woofer in the process

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Old 8th July 2010, 04:23 PM   #62
badman is online now badman  United States
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Originally Posted by Patrick Bateman View Post


I should post some pics of what I did to my poor Trio8 woofers

I was trying to get them to work in a small tapped horn, and cut out the dustcap hoping it would lower QMS (and QTS.)

Unfortunately, it barely made a difference, and ruined the woofer in the process

That's a big no-no with vented poles. You can get replacement dustcaps from OC speaker repair, get 4 or 6 to make sure you get a thick and strong enough one. You can also use a phase plug, or some other method of covering the pole vent if you wish.

Unless there's more wrong than that....
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Last edited by badman; 8th July 2010 at 04:32 PM.
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Old 8th July 2010, 04:49 PM   #63
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Originally Posted by Patrick Bateman View Post
Unfortunately, it barely made a difference, and ruined the woofer in the process
Doh

Have you modeled the TC Sounds Epic 10" and Axis 12" woofers yet? I'm starting to get all excited about them. Someone at AVS alerted me to the 10."
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Old 8th July 2010, 06:30 PM   #64
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Originally Posted by badman View Post
That's a big no-no with vented poles. You can get replacement dustcaps from OC speaker repair, get 4 or 6 to make sure you get a thick and strong enough one. You can also use a phase plug, or some other method of covering the pole vent if you wish.

Unless there's more wrong than that....
Yeah I found that out the hard way lol

(It is indeed a vented pole piece.)

One thing that I've wondered about tapped horns is if the cone material has an effect on their efficiency. Here's what I mean by this, and if this makes no sense, don't be surprised

For instance, I've built half a dozen tapped horns. Two of them used the MCM 55-2421. I've had a VERY VERY difficult time getting the MCM subwoofers to match the predicted response.

On the other hand, the rest of my tapped horns were VERY consistent with the predictions.

At first I thought the problem was leaks in my subwoofer construction. But then I began to wonder about the woofer itself. For instance, the subwoofer in this thread has an aluminum cone and a rubber surround. But the MCM 55-2421 has a *very* light paper cone, and an untreated foam surround.

Which makes me wonder - can air be leaking right through the cone itself?

I'll admit, it's a stretch. But I've noticed that the P-Audio SN-12MB doesn't exhibit the same problem, and the P-Audio does NOT have a vented pole piece. The density of the paper used by P-Audio also seems higher.

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Old 8th July 2010, 06:34 PM   #65
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Originally Posted by Oklahoma Wolf View Post
Doh

Have you modeled the TC Sounds Epic 10" and Axis 12" woofers yet? I'm starting to get all excited about them. Someone at AVS alerted me to the 10."
I've been running this infrasonic tapped horn for a couple weeks now. Honestly, I wouldn't use this sub for music. You can't hear a difference The TH-Mini is smaller, cheaper, more efficient, easier to build, etc... It's a very very good sub for music. I couldn't say enough good things about it.

OTOH, the sub from this thread is a MONSTER on home theater. Last Saturday I had some people over to listen to my Summas, and this subwoofer is downright *frightening* when you're playing a movie. There's TONS of low frequency content in movies, I had no idea how much until I built this.

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Old 8th July 2010, 06:39 PM   #66
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I've been running this infrasonic tapped horn for a couple weeks now. Honestly, I wouldn't use this sub for music. You can't hear a difference The TH-Mini is smaller, cheaper, more efficient, easier to build, etc... It's a very very good sub for music. I couldn't say enough good things about it.

OTOH, the sub from this thread is a MONSTER on home theater. Last Saturday I had some people over to listen to my Summas, and this subwoofer is downright *frightening* when you're playing a movie. There's TONS of low frequency content in movies, I had no idea how much until I built this.

The reason that I posted this "mini review" is that a lot of the woofers available from TC Sounds, Diycable, and Creative Sound are best suited to infrasonic tapped horns. This is because tapped horns work well when they're tuned to 0.707 times the FS of the driver. Which means that a woofer with an FS in the range of 25-35hz will only work well in an infrasonic tapped horn. IE, you're not going to get good efficiency at 40hz with one of these big heavy drivers.
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Old 8th July 2010, 07:51 PM   #67
godfrey is online now godfrey  South Africa
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Originally Posted by Patrick Bateman View Post

<snip>
At first I thought the problem was leaks in my subwoofer construction. But then I began to wonder about the woofer itself. For instance, the subwoofer in this thread has an aluminum cone and a rubber surround. But the MCM 55-2421 has a *very* light paper cone, and an untreated foam surround.

Which makes me wonder - can air be leaking right through the cone itself?
</snip>
I wouldn't be surprised if it's the surround.
Apparently, in high-pressure systems, flimsy surrounds can "flip". e.g. when the cone pushes out, the surround gets sucked in (and vice versa), so you lose a significant proportion of your volume displacement.

I remember seeing an investigation into this somewhere, with a high-speed camera showing the effect very clearly. Unfortunately I have no recollection where in the web it was.
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Old 8th July 2010, 08:38 PM   #68
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There's TONS of low frequency content in movies, I had no idea how much until I built this.
Yup - with the right movie, it's a lot of fun
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Old 9th July 2010, 02:05 PM   #69
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I watched the Dark Knight with one eye on the screen and one eye on the 8" driver in my sub... Scary. Some of the effects eats excursion like it's going out of fashion.
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Old 9th July 2010, 02:15 PM   #70
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I watched the Dark Knight with one eye on the screen and one eye on the 8" driver in my sub... Scary. Some of the effects eats excursion like it's going out of fashion.
Don't you guys use sub-something filters? Might be smart. Of course, you'd have to decide what "sub-something" was. Like maybe 8 incher flapping in the breeze with no perception of it by listener except by eye.

Esp. souls with enclosures that let go (all enclosures except for sealed ones or Klipschorn with sealed box in back of driver, eh).
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