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Graham Holliman Velocity Coupled Infra Bass Speaker?
Graham Holliman Velocity Coupled Infra Bass Speaker?
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Old 7th July 2011, 03:13 AM   #211
Upstate NY low life is offline Upstate NY low life
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I really am trying to add to this discussion and revive it, although my first post wasn't all that great. If I had of known it would need approval it would have been different.

Okay, since all your old zip's and pdf's are now gone and there are better ways of doing things anyway, could someone post good pictures here of this thing finished or CAD pictures illustrating it's construction. I would like to try it at some point. Does anyone know an actual efficiency percentage for any given driver in this type of enclosure?
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Old 8th July 2011, 12:01 AM   #212
Upstate NY low life is offline Upstate NY low life
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What doesn't make sense to me is that if all three sizes (10, 12, and 15) of this thing are intended to reproduce the same frequency range, how can they have difference enclosure sizes. From what I understand, the tuning frequency of an enclosure is the same no matter what driver is in it. And especially with the intricate design of this enclosure to do what it does with such efficiency, it seems like it would have to be either and exact size or an exact fraction of the wavelength of it's tuning frequency to put out such a powerful frequency without having to be built like a tank (basically one layer of 3/4 was recommended). This type of enclosure is clearly designed to work smarter not harder. Or am I mistaking and the enclosures are the same size but different thicknesses. The guy from South Africa made a pdf detailing how to do it based on what he claims to be his copy of the original article which for some reason he didn't just scan and post here and on AVforum.

Last edited by Upstate NY low life; 8th July 2011 at 12:07 AM.
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Old 8th July 2011, 12:30 AM   #213
weltersys is offline weltersys  United States
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Quote:
Originally Posted by Upstate NY low life View Post
What doesn't make sense to me is that if all three sizes (10, 12, and 15) of this thing are intended to reproduce the same frequency range, how can they have difference enclosure sizes. From what I understand, the tuning frequency of an enclosure is the same no matter what driver is in it. And especially with the intricate design of this enclosure to do what it does with such efficiency, it seems like it would have to be either and exact size or an exact fraction of the wavelength of it's tuning frequency to put out such a powerful frequency without having to be built like a tank (basically one layer of 3/4 was recommended). This type of enclosure is clearly designed to work smarter not harder.
22 pages of hearsay and subjective BS, no frequency response or SPL charts, observations that it needs a certain size concrete bunker to work, and you decide this johnny one note low tuned boom box "is clearly designed to work smarter not harder".

Have fun in your pursuit of this red herring !
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Old 8th July 2011, 01:15 AM   #214
just a guy is offline just a guy  Canada
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Wow, it's been a long time since saw this thread. I was pretty interested in this design at the time but I was also pretty young and stupid so you can pretty much disregard anything I posted.

I lost interest when Bibster's .wav file matched Bjorno's modeling fairly well, proving that there really isn't much (or any) really low bass happening in the 10 inch version. I can't even remember what I went on to next but I have learned a lot since then and I'm certainly not interested in this type of box anymore, aside from academic curiosity.

I was always curious how Bjorno modeled this with MJK's worksheets, now that I have them I might go back and check what he was doing. I still don't think MJK's software can really model this accurately (and if it can I'm really interested to see how he did it) but I do believe Bjorno's models were close enough based on Bibster's results, and I no longer think Akabak would have trouble simulating it.

I might look at this concept again if I have time, but as I said, only out of academic curiosity, not because I expect it to live up to the claims in the various patents and documents.

Last edited by just a guy; 8th July 2011 at 01:18 AM.
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Old 8th July 2011, 01:28 AM   #215
Upstate NY low life is offline Upstate NY low life
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One thing I noticed was that the south african's box, aside from looking a little ratty, was much smaller than another thread suggested it to be. Something on the order of 5 x 4 x 2.5 feet, but that was for the 18 inch one. Like I said, it only seems like one size would work and of course the room would be a HUGE factor for such a thing. If you haven't noticed the room generally means more and more the lower you go. Hence, these things wouldn't be worth their bonfire capacity at an outdoor venue :lol:

I believe the way it works is that the room has to be medium sized and fairly well sealed (wait, doesn't this sound strikingly familiar, cough*rotary woofer*cough). Because basically you are in the speaker enclosure at this point and when it's that low it's essentially just acting as an air de/com pressor.

Which gives me a lovely idea. Build a very large rough sealed box large enough to get inside of it and let her rip after someone seals me in with the woofer/door.

Imagine the spl, or better yet save it, imagine the apl difference inside of a sealed enclosure

Last edited by Upstate NY low life; 8th July 2011 at 01:43 AM.
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Old 8th July 2011, 02:30 AM   #216
revboden is offline revboden  United States
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you asked. the pdf is at the bottom of the page.

Graham Holliman Infrasonic Generator - AVForums.com
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Old 8th July 2011, 02:50 AM   #217
Upstate NY low life is offline Upstate NY low life
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Yes I know about thay. That's the "22 pages of hearsay." If I made one of these it would be a large one for efficiency since space is not an issue. But I have absolutely no guideline for the original 18" one. That's why I was re-searching for advice, pics, instructions, CAD renderings, etc. I am tired of the wastefullness of traditional systems. They are non sustainable
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Old 8th July 2011, 04:23 AM   #218
boydon_lepasci is offline boydon_lepasci  United States
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While I have never seen dimensions for larger than a 15", I imagine that the larger the chamber you induce a resonance in, the more of a room you can involve or more aperiodic a room you can overcome. I would expect a larger Helmholtz chamber to require a larger driver to excite it.
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Old 8th July 2011, 04:42 AM   #219
Upstate NY low life is offline Upstate NY low life
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True. Is there a direct correlation between the 10, 12, and 15 inch models that would allow us to extrapolate the dimensions of the 18 inch one? Besides the size, are the designs otherwise exactly the same? And do you have the dimensions for the 10, 12, and the 15 inch one besides through the south african's pdf? All the other zip's and images have lost their hosting. Could we try to gather as much as possible? Use flickr and other less volatile hosters than were used in the past decade.
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Old 8th July 2011, 06:40 AM   #220
Upstate NY low life is offline Upstate NY low life
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If I were to build this I would need a good, old fashion style, low excursion but high quality driver. I just tore apart an 18 inch woofer now. Here is the voice coil:

Click the image to open in full size.
I regret ever buying such cheap junk. This was out of an extremely inefficient Pyle speaker, the silly looking blue one (pl1890bl) and the sad part was that it only cost a little over 100 USD including shipping.

One driver that has my attention is the Focal 46 kx4 which actually doesn't look all that impressive at all (lol) but is very expensive and made with exotic materials, such as the magnet which has a high density of quality, something I like.
Focal 46 KX4 - 18" Quad 1-Ohm Subwoofer#

However, this is very expensive and may be altogether unnecessary for this application. You guys are the DIY guys, so if anyone you could make me a speaker that better replicates the old style stiff suspension speakers Graham was using.

Last edited by Upstate NY low life; 8th July 2011 at 06:46 AM.
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