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Old 11th July 2010, 01:33 AM   #81
Mark Kravchenko
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Horn Bias! ESL's RULE!

Yep hard to beat an ESL for radiation efficiency. But they are a whole other ball of wax. I have to build this one day. It would probably be my last speaker. That and this sub.

Home Page of Arto Kolinummi, Audio

Check out his fullrange ESL and stepup transformer. This is one guy I like. And he is quite open about helping you work on a copy of his design. THe transformer your on your own though. But if you have enough readoing time and some persistence it can be worked out.

Mark

Maybe Patrick should post some of his findings so I can stop hijacking this thread. Sorry Patrick. I just answer the questions as they come. I can't post about your horn cuz I don't know how you built it.
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Old 24th September 2012, 11:34 PM   #82
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Quote:
Originally Posted by Patrick Bateman View Post
Click the image to open in full size.

This illustration makes it easier to follow what the path is in the horn. While it wasn't intentional, this layout is very similar to The Tower of Power. I didn't even notice until I was reviewing the patent today.
I tossed this sub.

Click the image to open in full size.
Click the image to open in full size.

Things I like about this sub:

- it really does play below 20hz
- for home theater, you can really notice a difference. There is definitely content below 20hz in movies
- it's as 'tight' as any I've heard

Things I don't like about this sub

- it rattled like crazy. Even with crossbrace after crossbrace after crossbrace it rattled. There is clearly a much higher construction standard required for subs that play to 10hz. I'm guessing this is because it takes so much power and so much excursion to make bass below 20hz
- it's preposterously large
- the large size wouldn't be the end of the world, if there was an easy way to move it. For instance, if I had to build a giant sub again, I would likely use an array of two subs instead of a single unit. (IE, two subs with the same cubic area as this one, or less)
- it's ugly


In summary, I will likely build another infrasonic sub one of these days. But it will likely be smaller, and it will be easier to move. And it will definitely be built with far more sturdy construction.

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Old 25th September 2012, 12:59 AM   #83
GM is online now GM  United States
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Yeah, I did a dual 55-2421 ~10 Hz TH sim early on and it's all of 97.863 L, so takes four of them to get 115 dB/16 Hz/1 pi, but at this size, driver cost, it's the way to go IMO.

GM
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Old 26th September 2012, 08:40 AM   #84
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Quote:
Originally Posted by Patrick Bateman View Post
I tossed this sub.
Things I don't like about this sub:
- it rattled like crazy. Even with crossbrace after crossbrace after crossbrace it rattled.
In summary, I will likely build another infrasonic sub one of these days. But it will likely be smaller, and it will be easier to move. And it will definitely be built with far more sturdy construction.
Patrick,Yes, can't ever be too sturdy or braced, but the rattling may have been from the plywood itself, which looks to be AC or even CDX, the internal voids can be problematic.
That said, enough VLF will rattle so many things it is often hard to chase down all the culprits in room.

"Infrasonic" is an archaic term (IMHO) in the age of subs delivering SPL below 20 Hz that can be easily heard as well as felt.
There is a #@&k load of hump de do whomping when you go below 25 Hz, drywall stud walls start making their own gravy.

Art
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Old 26th September 2012, 11:23 PM   #85
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Patrick,Yes, can't ever be too sturdy or braced, but the rattling may have been from the plywood itself, which looks to be AC or even CDX, the internal voids can be problematic.
Agreed. My two 16Hz designs are built with 3/4" 11 ply void free shop birch. One's completely unbraced. The wood doesn't rattle, but everything else in the room sure does.
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Old 27th September 2012, 12:50 PM   #86
DrDyna is offline DrDyna  United States
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Originally Posted by weltersys View Post
There is a #@&k load of hump de do whomping when you go below 25 Hz, drywall stud walls start making their own gravy.

Art
Oh, man do they ever. Of the two walls in my room one of them is studs-against-concrete, which stays put, but on the other side, it's just drywall and studs with another room on the other side of the wall. The TH's I just built a few days ago can breathe the wall back and forth between 18 and 30 cycles or so to the point where they're making their own music.

I've been contemplating what I'm going to do about it. I might just go buy 20 more studs and stack them all the way across that wall.

If you can stand copious amounts of distortion from my cel phone camera, I've got a video up of my walls and bar area turning into butter.

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Old 10th October 2015, 04:53 PM   #87
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Over on diyma, we were having a discussion of various alignments.*

I think this project is an interesting example of what tapped horns are good at. Basically you can get a REALLY low F3 with a tapped horn, and a lot of output. Sealed boxes will always be smaller, and front loaded horns are probably capable of maximum SPL, but TLs can really go low.

If I were going to do this project again, I'd use multiple cabinets, and it would probably looks something like this:

Click the image to open in full size.
Here's the response of a single DIYMA12 in a 247 liter tapped horn. (8.7cf)

Click the image to open in full size.
The response includes a 13hz LR4 highpass. This filter is absolutely critical; without it you run a real risk of damaging the driver. Due to the low F3, even two hundred watts is pushing it. The sim is with 250 watts.

But it would be a heck of a sub for an inexpensive home theater. You're looking at less than $200 for the woofer, $80 for the processing, and under $200 for the amplification.

Click the image to open in full size.
For comparison's sake, here's FOUR of the twelves, in a sealed box equal in size to the TH. We can see the sealed boxes do well, as long as you use a lot of them. But this gets expensive; you're looking at four times as many drivers and four times as many watts.

Click the image to open in full size.
Here's a pic showing the excursion. Once again, due to Hoffman's Iron Law, excursion is quite similar above the F3. But excursion gets crazy in the TH, so you MUST use a highpass filter on it. On the sealed boxes, you can get away without it. (Though it wouldn't hurt.)

TLDR: If you have a lot of space, a single 12" woofer in a TH can be a real monster for ULF effects in movies. If you don't need to get down to 15hz, a pile of sealed boxes is probably less hassle (if you can afford it.)

* Car Audio | DiyMobileAudio.com | Car Stereo Forum - View Single Post - School me on T-Line
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Old 10th October 2015, 06:39 PM   #88
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Here's a little test to determine if anybody you talk to about sims actually understands what they are talking about. Just ask them, "If the larger the sealed box the lower the F3, how come sims want you to make small sealed boxes?"*

And if they can't answer that question, they shouldn't be play-engineers with their sims.

Ben
*just in case they (or oneself) do know the nominal reason, ask them (or think about it yourself) if the reasoning really makes good sense.
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Last edited by bentoronto; 10th October 2015 at 06:42 PM.
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Old 10th October 2015, 07:16 PM   #89
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Originally Posted by bentoronto View Post
Here's a little test to determine if anybody you talk to about sims actually understands what they are talking about. Just ask them, "If the larger the sealed box the lower the F3, how come sims want you to make small sealed boxes?"*

And if they can't answer that question, they shouldn't be play-engineers with their sims.

Ben
*just in case they (or oneself) do know the nominal reason, ask them (or think about it yourself) if the reasoning really makes good sense.
More like "This is a little post that's completely off topic to let everyone know I don't like sims or the people that use them".

Ben, I've told you at least a dozen times that sims don't want anything. How can a sim want you to build a small sealed box? Or anything else? I'm not sure why you can't understand that a simulator takes user inputs and gives information based on those inputs. IT DOESN'T WANT ANYTHING. Some simulators have default options but those are still user selected and can always be editted.

Anyone can sim anything they like, from a small sealed box to an IB (large sealed box) to a tapped horn or anything else.

What YOU choose to build should be a compromise considering a lot of different variables - in the case of small vs large sealed you should be looking at how much space you have available, response curves of the various size boxes (system q), how much power you have available and how much the driver can handle and a bunch of other stuff.
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Old 10th October 2015, 08:09 PM   #90
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It is clear you don't understand how the sim works.
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