Graham Holliman Velocity Coupled Infra Bass Speaker? - Page 3 - diyAudio
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Old 13th June 2004, 04:44 AM   #21
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Quote:
Originally posted by synergy
it does exist, the patent's here

i'm interested in this

why is it so room fussy tho? is it simply because of having to presurise the space enough to produce these frequencies?

why do you say that if you turn it up the worse it sounds?

any ideas on how to work out the required chamber volume and port sizes for any given driver?
MAYBE
start with what you know. its a 'tline' with sealed chamber on the end. Perhaps start with the sealed chamber resonating at say,50hz with the driver on it,as per normal. Then work out the port for the same sized box,tuned low,then see if it works :P

Perhaps only low excursion woofers were available or,
loading is not sufficient to provide decent spl with low cone movement

(makes me think it is being used where it shouldnt be)
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Old 14th June 2004, 12:09 PM   #22
fragma is offline fragma  South Africa
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Default Finished typing out plans

Hi all you bass (infra) fanatics.

I have finished typing out all the plans...under huge pressure from you bunch!!

Anyway, Ill post the plans, all typed out by me ;o) as well as all the diagrams, as well as my personal experiences and tips i can help you with that i had to figure out on my own, as well as include all the tips i wrote in here. I see so many people have downloaded the plans up to where i typed, so ill rather fishish it and post it in a day or two once and for all, then I just hope you all build and tell me your results and hints you come up with.

Ill post on the 16 June latest. Its a public holiday here in South Africa, so ill complete it then. (Yes its winter here, and we sitting in 3 degrees centigrade morning temperatures. We not used that cold here.

NOTE : Also as paradise-ice explains, infra bass can be dangerous to health and property. In fact listening to the same low bass piece for two hours for testing and positioning of my new box, i ended up with neck-ache, dizziness, nausia, and had to have a break for 3 days before i could listen again....all that on a tiny system....be careful!
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Old 14th June 2004, 12:28 PM   #23
fragma is offline fragma  South Africa
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Default Answers to some Q's

Some questions

Q. why is it so room fussy tho? is it simply because of having to presurise the space enough to produce these frequencies?

A: You will see in the plans why you need a SUITABLE listening environment. He explains, but not explicitly says that the box raises and lowers the overall pressure of the listening environment. It stands to reason then that if you leave the door open, how do you pressurise the room. If you have a hole in your car tyre, how will you pump the wheel up to its correct pressure?



Q:why do you say that if you turn it up the worse it sounds?

A: Good question. Remember i was on a tight students budget. I only had an 80W rms 10" speaker, and a 30Watt rms NAD amp.
Of course if you turn it up too much, massive distortion is going to take place. I dont have a huge amp, and powerful speaker to test it to the limit. Besides i didnt want to kill thy neihbour. I would love someone to try this box with the more powerful equipment. Remember the distortion is also less the softer you play the speaker (within reason) and i found that the less the cone moved, the deeper, and purer the sound was. I dont believe my amp could drive it.



Q: any ideas on how to work out the required chamber volume and port sizes for any given driver?

A: Dont worry about that. The plans ill post on 16th june include 3 designs. All dimensions included to build a 10", 12", and 15" design. My 10" blew me away. 15" i think would stop your heart.
When youve heard bass down to about 10Hz or so...its indescribable, and youll understand what i mean then.

ryan
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Old 14th June 2004, 12:44 PM   #24
fragma is offline fragma  South Africa
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Default seems to be a different patent

Hi Mikee12345,

it seems the patent you found, is different to the one i have. However the same rules would apply, except that the ports on the one I built have rectangular ports, not round.
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Old 14th June 2004, 12:54 PM   #25
sreten is offline sreten  United Kingdom
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Whilst the principle might be capable of producing very low
frequency bass I'd suggest the caveat is that this is not
accurate low frequency bass, transient response is poor.

I think this can be observed by simple inspection, just consider
trying to use the principle for say bass in the 30Hz to 50Hz region.

I remember the whole debate about the principle well, and I
was basically in the sensible camp, saying that considering
the principles of vinyl reproduction the idea is at best a novelty,
getting down to 20Hz with good quality is far more important.
GH's suggested mods for tonearms were / are a non-starter.

With digital its very different if your subsonically inclined, though
I can't imagine a highish Q boom box sounding that pleasant.

sreten.
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Old 14th June 2004, 01:53 PM   #26
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Default Re: Answers to some Q's

Quote:
Originally posted by fragma
Some questions

Q. why is it so room fussy tho? is it simply because of having to presurise the space enough to produce these frequencies?




Q: any ideas on how to work out the required chamber volume and port sizes for any given driver?

A: Dont worry about that. The plans ill post on 16th june include 3 designs. All dimensions included to build a 10", 12", and 15" design. My 10" blew me away. 15" i think would stop your heart.
When youve heard bass down to about 10Hz or so...its indescribable, and youll understand what i mean then.

ryan
I agree totally!, a pressure wave that is so low it cant be heard but felt its incredible, seldom in life do we have a chance to experience and feel infra-waves and the exposures we do get are from jet engines or earth quakes, tidal waves or Hugh thunder bolts cracking the air like Thorís might Hammer! I can pressurized a carís interior much easier than an average room for infra-waves and honestly It makes people physically sick, I have not pin pointed the frequency that effects the body in such a manner, as I use a sweeping sine wave from 1Hz to 25Hz that runs from a Laptop, I cant find a subject that is willing to allow themselves to be a ginipig for these experiment, what a surprise, as a long exposure of 30 seconds is needed, but some people can take 3 minutes of high pressure infrawaves, and to the person on the outside that cant hear or feel anything, its surprising to see a person inside the car look terrified! This feeling can last for hours, with real physical symptoms, apparently a tigers roars has infra sound in it and anybody that has had a tiger roar or growl at them will tell you they were terrified!
If you submit plans for this design, I promise to make a working prototype! I have access to as many infra woofers that I need so thatís not a problem for me. The only problem is people actually want to urinate after a short exposure, maybe making this device in a rest room is a better idea,LOL

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Old 14th June 2004, 02:48 PM   #27
Volenti is offline Volenti  Australia
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heh, I quite like infrasound, had a setup in my car at one stage that would get ~120db at 10hz (possibly more depending on the accuracy of my mike at that frequency) and I found it to be quite relaxing (would feel sleepy after a while), that's with music containing infrasound though, not pure tones.
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Old 15th June 2004, 08:01 AM   #28
Colin is offline Colin  United Kingdom
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Infrabass down to 5Hz sounds dangerous in an unmonitored environment. Wonder if it would be possible to modify the design to give a safer cutoff of around, say, 15Hz?
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Old 15th June 2004, 08:14 AM   #29
fragma is offline fragma  South Africa
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Default Agree with Volenti

Hi again,

I have to agree with Volenti. I have played around with a sinewave generator at university, playing around with a few home amps and speakers purely for fun and experimentation. The pure sine wave although producing a sound, lacks higher order harmonics, i.e. musicallity. Deep sounds from a pipe organ for instance played as quick as any other higher note really warms the soul. I personally would vomit if i tried to listen to a 10Hz signal for as long as i could bear. Thats torturerous endurance tests. My aim was to hear more in the music. In fact a particular song number 4 on Enya's watermark (ill double check that number) i can only listen to for about a minute or two before i have to fwd. It has a continuous low fr that exists throughout the song without letting up, but this is more the exception than the rule.
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Old 15th June 2004, 08:46 AM   #30
RHosch is offline RHosch  United States
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I can understand the principle generating subsonic information, and even doing it with flatish frequency response. I don't understand how a small displacement driver is supposed to do so with any significant SPL... even using tremendous amounts of resonance.
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