| Neopsp |
Has anyone here heard about the Graham Holliman Velocity-Coupled Infra-Bass Speaker? If is a very old design but a very efficient VERY low sub woofer box. I discovered the plans a while back and I dont know what driver to use. In the plans they say there is a LED circuit also to indicate the presence of infra bass activity (potentially dangerous!!). The crossover is also mentioned but the diagram of specifications are not given. I am trying to keep this as original as possible so if anyone has any of this information or has every heard of this design please let me know.
Thanks
Neopsp :) |
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| AndrewJ |
Wow, I haven't heard about this speaker in a very long time. I was never convinced of the merits, or explanation given, of the technology, but i do have a copy of the patent somewhere in the depths of my files.
I do not believe the claims of high efficiency bass from small enclosures that many people tout. These claims are rarely substantiated. |
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| Neopsp |
I made contact with someone that has build the speaker and even has a letter from Graham Holliman. He was not to impressed by the Sub either. He said it was very boomy. I want to build this sub out of curiosity anyway :) . I am thinking of saving up for the Shiva 12" driver for such a project. What do you people think? When I oneday get enough money together and get the time (not within the next 3 months :) ) I will post what it sounds like.
Thanx
Neopsp |
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| tomcat |
I recall something in "Hi-Fi Answers" mag in the mid 70's by the author but it wasn't small. It used a 15 or 18" Atlas driver from the UK specialist speaker maker Richard Allan Radio Ltd. I suggest you get in touch with Haymarket Publishing, London UK. They published a swag of Hi-Fi mags in the 70's of which Hi-Fi Answers was just one. These titles over the years eventually got rolled into one that is published today as "What Hi-Fi". If you are lucky they may still have something on file...
tomcat ;) |
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| fragma |
Hi there, I see the posts here are rather old, however i did build the 10" unit and there are some very interesting things i found.
1. The box is very room fussy. The room needs a sealed room. Closed doors, and windows. In an open plan lounge kitchen etc, you wont even notice it. However if you do have a sealed room, preferably with a cement roof, floor, it will blow your mind.
2. It has to be coupled out of phase to your normal speakers. Positive to negative, and negative to positive. The output sound is 180 out of phase, and hence requires this.
3. The louder you play the speaker, the worse it sounds. Its extremly efficient in my opinion, and in the right room, even tapping on the back of the speaker cone, the room shakes. So...
4. ...in my opinion, a stiff cone, and a powerful amp are in order. The less the cone moves with low frequencies, the better the sound. If you turn it up with low fr's, it just flutters with the speaker struggling to get to its excursion limits.
5. Hence the reason why some ppl call it boomy...if its not in the right room, you just hear a little bit of a boom....nothing more.
6. However, in the right room, of which i have found only two...(my parents lounge,and in a student commune. The room was all cement, about 7meters X 7 meters, cement floor, and roof, and 2 sliding doors. All closed of course.
Even at 9 o clock on the amp dial of a cheap kenwood mini system concected in parrallel passive to one of the outputs, playing a pipe organ recording...my eyes were almost coming out of their sockets. As for purity, the deep tones were so distinct you could hear the individual beats of the low fr's. I could almost feel the air it was so thick. Its the lowest sub ive ever heard, and no one has ever demonstrated otherwise to me....not even on a $2500 active sub.
7. One drawback however is the very noticable gap between your 40Hz floor standers and the point where this sub starts breathing...at around 25Hz and down. You need a conventional sub to fill the gap. This design is for Extremely low fr's.
8. The danger to property and health...its true. After spending 2 hours on optimal placement, i had to take a break for 2 days. I had neck pain, and dizziness. (a number of times)
9. You REALLY do hear incredible sounds like mic bumps through the amp of a live recordding like Eric claptons unplugged. Song number 4, (12 or 10) on Enyas watermark, and few others...not many.
In Enya number 4, there is a sub fr undertone of around 15Hz the entire song that you cant hear on a conventional system. However, half way through the song you need to turn it down ....its too much to bear, but serves as a great demo.
10. Crossover, and driver. Well, at the time of building, i used an old cheapo Vifa 80W 10" driver, no crossover, and passive into that cheap kenwood Hi-fi, and that nearly blew me away even on a low volume. I fear anything more powerful than that!!!!!!!!!!! |
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| Bill Fitzpatrick |
What's a Graham Holliman?
Your post is standing alone where it seems that it was meant to be part of an existing thread. |
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| fragma |
Hi there, I see the posts here are rather old, however i did build the 10" unit and there are some very interesting things i found.
1. The box is very room fussy. The room needs a sealed room. Closed doors, and windows. In an open plan lounge kitchen etc, you wont even notice it. However if you do have a sealed room, preferably with a cement roof, floor, it will blow your mind.
2. It has to be coupled out of phase to your normal speakers. Positive to negative, and negative to positive. The output sound is 180 out of phase, and hence requires this.
3. The louder you play the speaker, the worse it sounds. Its extremly efficient in my opinion, and in the right room, even tapping on the back of the speaker cone, the room shakes. So...
4. ...in my opinion, a stiff cone, and a powerful amp are in order. The less the cone moves with low frequencies, the better the sound. If you turn it up with low fr's, it just flutters with the speaker struggling to get to its excursion limits.
5. Hence the reason why some ppl call it boomy...if its not in the right room, you just hear a little bit of a boom....nothing more.
6. However, in the right room, of which i have found only two...(my parents lounge,and in a student commune. The room was all cement, about 7meters X 7 meters, cement floor, and roof, and 2 sliding doors. All closed of course.
Even at 9 o clock on the amp dial of a cheap kenwood mini system concected in parrallel passive to one of the outputs, playing a pipe organ recording...my eyes were almost coming out of their sockets. As for purity, the deep tones were so distinct you could hear the individual beats of the low fr's. I could almost feel the air it was so thick. Its the lowest sub ive ever heard, and no one has ever demonstrated otherwise to me....not even on a $2500 active sub.
7. One drawback however is the very noticable gap between your 40Hz floor standers and the point where this sub starts breathing...at around 25Hz and down. You need a conventional sub to fill the gap. This design is for Extremely low fr's.
8. The danger to property and health...its true. After spending 2 hours on optimal placement, i had to take a break for 2 days. I had neck pain, and dizziness. (a number of times)
9. You REALLY do hear incredible sounds like mic bumps through the amp of a live recordding like Eric claptons unplugged. Song number 4, (12 or 10) on Enyas watermark, and few others...not many.
In Enya number 4, there is a sub fr undertone of around 15Hz the entire song that you cant hear on a conventional system. However, half way through the song you need to turn it down ....its too much to bear, but serves as a great demo.
10. Crossover, and driver. Well, at the time of building, i used an old cheapo Vifa 80W 10" driver, no crossover, and passive into that cheap kenwood Hi-fi, and that nearly blew me away even on a low volume. I fear anything more powerful than that!!!!!!!!!!!
HOWEVER, I would like to see detailed instructions on the driver types to use(Long excursion speakers or very stiff types), how to mount the driver unit (whether you use spacers or just bolt it down), and any other tips, i.e. (crossover circuits, fr's etc.)
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| fragma |
Hi Bill,
Sorry about that, Im new to the forum, so instead of clicking reply to thread, i created a new one. It was meant to go under the Graham Holliman bass enclosure some guys were talking about. If you search on google for "graham holliman" youll find the threads.
A bit more about it. Its called the Graham Holliman Velocity Coupled Infra Bass Speaker. Its an enclosure design from the year dot. Its very complex to build, but if you do a bit of diy, its not so difficult. I built the 10" version, but you can build the 12" or 15" design. Its an enclosure that works very differently from normal subs in that it increases and decreases the overall pressure of the listening room to achieve a bass response like you cannot believe. However, if you read (and you did) my response, it hence needs to be in a room, with all the doors shut, and windows shut to get the full effect. Open plan house just wont work at all. The lowest fr's im convinced i heard was in a room about 7mX7mX3m, cement roof, and floor...and simply plugged it into a mini system passivly (no filters, or amps) to the right channel (remember it must be connected wrong way around to work) and boy...i thought the space shuttle was taking off. Its not a sub you blast power into in my opinion, its so efficient, it takes a minute amount of power to reproduce VERY low fr's
The design notes claim it extends from 5Hz-25Hz. Yes...thats 5!!
Now shoot me if im wrong, but im sure ive heard mine go as low as about 12-15Hz, and i built the baby one!!!
If you dont hear low fr's immediatly even at low volumes, then the room is wrong....its room fussy to the extreme!
If you want the designs i have them on hard copy, i can scan them if you interested.
regards
ryan |
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| Coolin |
I'd like the designs you have please...
thanks,
Coolin |
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| dhenryp |
| So how about a picture or a link to more detailed description/plans. |
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| fragma |
Hi guys,
I was replying to some guys who already had the plans, however, seeing that you guys are so interested, I shall type out the document, and scan all the images and diagrams for you and send them to you. I only have a hard copy I was given some 9 years ago, so youll have to give me a few days to type it out. I have just typed out the introduction. The next few pages are all bout the cabinet construction. So give me your email addresses and ill send the word document as I update it with the rest of the article. Ill send to you what i have in the mean time.
PS: No...im not joking by the way. Upon reading these plans again, I noticed the author stressing "in the correct accoustic environmen" meaning to me ....a room you can shot all the doors and windows to create a "pressure chamber". and open plan listening environment wont do at all!
PSS: Email me at oiltanker@webmail.co.za...and ill reply to you with the plans as I type them out.
regards
ryan |
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| fragma |
| Aha....didnt see the attachment thingy magafta.....check it out sound enthusiasts |
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| Coolin |
| quote: | Originally posted by Coolin
I'd like the designs you have please...
thanks,
Coolin |
Thanks for all that typing. But the fact that you did type it yourself instead of scanning still has me a little woried about it being a joke or not :) :rolleyes:
I'll be awaiting the rest.
Coolin |
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| Colin |
Hi - Just caught up with this thread. Coincidence as I was attempting to describe the Graham Holliman design on the fullrange forum a couple of weeks back. To the doubters - yes, it does exist. The designs appeared in Hi-Fi Answers in the UK in the late 70s or early 80s. At the time, it was pre-CD so the author used a coin on top of his pickup headshell to get incfrabass from his turntable!
As I no longer have copies of the articles, I'll be interested in seeing them again.
Colin (note spelling - this could get confusing) |
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| Colin |
PS to fraqma - I'm away from my main computer at present. When I get back next week, I'll post again and see if you want to try emailing me the scans of the articles and I'll try putting them through my OCR program.
Colin |
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| dazydee |
Hey, I was just about building myself a new infrasonic Sub, but I think I wait until your finished typing. This could work in my living room.
Thanks for all tha work
Danny |
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| 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? |
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| pinkmouse |
| All tidy now, this thread merged with the original. :) |
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| Paradise_Ice |
Infrawaves are an important part of music but for us Audiophiles it should not be taken lightly, the effects of infrawaves on the body can have real effects that can affect your health short term!
the psycoacoustic respones will give you a pounding :smash: head and make you feel sick as long Johns Silvers Parrot:dead:
Stay away from Infra designed T-lines and horns,IMO,, but saying all this, it does give a sense of space,size and air in music:D |
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| amoeba86 |
I can think of another sealed environment you could use these, in fact it's designed to be sealed
...my car :D |
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| mikee12345 |
| 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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| fragma |
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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| 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?
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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| fragma |
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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| sreten |
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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| Paradise_Ice |
| 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 Thor’s might Hammer! I can pressurized a car’s 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 that’s 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:headbash:
:headbash: |
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| Volenti |
| 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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| Colin |
| 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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| fragma |
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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| RHosch |
| 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. :confused: |
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| 7V |
Sorry guys but I still don't know what this design looks like. I downloaded the zip file but it didn't have a graphic. From the description it sounds like a Daline.
Has anyone got a simple schematic? |
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| Coolin |
I think this is the underlying principle only larger.
I supose thats pretty effecient.
Coolin |
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| Paradise_Ice |
| quote: | Originally posted by 7V
Sorry guys but I still don't know what this design looks like. I downloaded the zip file but it didn't have a graphic. From the description it sounds like a Daline.
Has anyone got a simple schematic? |
| quote: | Originally posted by Coolin
I think this is the underlying principle only larger.
I supose thats pretty effecient.
Coolin |
Hi Steve
I have not seen this design yet myself, but i will make one if a design is given, modern drive units have much larger cone travel from ones made lets say 30 years ago, this was a limiting factor in the design way back then,IMO I am sure it will be like a Daline or T-line but working on another wave lenght i hope! It should be very effecient, to make infrawaves part of the music. There is nothing more impressive when demonstrating a pair of speakers when a person really has there :bigeyes: opened. |
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| synergy |
| quote: | Originally posted by 7V
Sorry guys but I still don't know what this design looks like. I downloaded the zip file but it didn't have a graphic. From the description it sounds like a Daline.
Has anyone got a simple schematic? |
check out the patent link back one page (providing you can do pdf's that is)
quite a comprehensive set of drawings and explainations |
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| fragma |
AT LAST,
I have completed the document. Pictures and all. Appologies for the large size of the document, but the diagrams need to be quite clear to figure out whats actually going on.
Best of Luck lads, and pls send me feedback on any developments or discoveries you might make.
Mail me on oiltanker@webmail.co.za
Best Regards
Ryan |
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| fragma |
OK, It seems my plans of 750k are too big compared to the allowed limit of about 100k.
Does is there anyone that can send the plans to to post here in some way, or on some site? |
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| qi |
There are ten full pages in the patent with lots of detail (I initially missed that ... DOH!)
...from the patent |
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| synergy |
i'd welcome your thoughts on this but first off thanks for the plans Ryan, i've put them on some space if anyone wants them, save hassling you too much eh? - Holliman.zip
right i've done a rough number crunch and i stress this was just a rough one i didn't have the time last night to draw it into a cad program and get the exact measurements
not having the specs available for the specially designed drivers originally used and without mailing wilmslow audio and having to wait for a response i've used 3 different drivers as a comparison (all eminence it was easier) and put it into AkaBak (the only thing capable of simulating this)
anyways i'm not entirely convinced for starters the efficiency wasn't as high as i was expecting and the smoothest line gave a 12dB roll off from 50Hz which could easily be obtained with a sealed box
however the biggest shock and this might explain the poor sound at high volumes was that at 1W the cone excursion was already well over 3mm
now it's quite possible i've made a mistake somewhere but i don't think so having rechecked it this morning
obviously better drivers maybe out there with tweaks to suit but see for yourselves - Holliman Response
black line = Kappa 15LF
green line = Beta 15
blue line = Alpha 15
i think it's possible the theory is sound however the application of it is flawed because of driver limitations namely the excursion and rather than using a low excursion driver a high one might be best ie the lab12 might be a good one
i didn't model it cos it would've meant redoing the whole thing
i might do so later as i'm going to have a play around with the whole design anyways and i'll let you know my results
the other side of this is bar movies and their effects what medium actually produces signals below 20Hz?
i was always under the impression the vinyl was cut between 30Hz and 15KHz with CD's being 20/20
bottom A on a concert grand might be 27.5Hz but i'm not convinced we hear that more than we do its harmonics
if that's the case are people simply feeling nauseous to some humble deck rumble or spurious groove distortion?
dave |
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| 7V |
I haven't had the time to look into this thoroughly yet but it may be that the Helmholtz resonator theory is close to the mark.
If so, I would guess that unless the box size is large, the Q of the resonator will be high, giving a very steep curve and a precise frequency that is 'amplified'. Either side of this frequency the response won't be so good.
Can anyone go further on the theoretical side of the design? |
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| synergy |
| i've mailed wilmslow audio with a view of getting details of the original drivers or something that would be suitable |
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| fragma |
Hi there.
Very interesting synergy, I think you'll bring lots of new ideas to this forgotten beast.
I must stress, that when i play the box and listen to music etc, I dont get sick at all, even with the box pumping away heavily sometimes. Its the prolonged exposure that made me feel a bit queezy. Im talking of playing the same low piece on repeat for 2,5 - 3 hours. After that I didnt want to know Graham Holliman or his speakers at all. However, 3 days break, and it was set up nicely, and again, it sounds really really lovely. It doesnt as i said blow me out the room, it just adds a gentle yet very low fr that gives the music a richness ive never heard before.
About a theorietical explanation, look at his entire write up as pointed out earlier in the forum at http://l2.espacenet.com/espacenet/v...gb&LG=en&DB=EPD
His theory is very interesting indeed.
The sounds you hear that are so low. I would also like to rip and send to someone. I have 3 in mind 2 from enya as i mentioned but that is easy to come by, and the third is a pipe organ piece that i find is the lowest "nice sounding" bass i have.
Ryan
PS: Thanks to synergy for posting the plans |
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| qi |
Ryan:
Thanks again for all of your work on this.
Synergy:
Great stuff simulating the design in virtual space!
I think there maybe something of use here.
For example, adding his chamber inside a Bose Cannon to augment the deepest bass segment. IMO the driver should be fully enclosed (ala Bose Cannon or 6th order bandpass) to only perform in the range of say 15hz to 50hz.
BTW, I have the ten page patent as one PDF file if you would like to post it... |
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| synergy |
qi you must be reading my mind mate i've been doing exactly that
interesting you should say about enclosing the driver i tried that and it returned a peak in response around 18Hz but dropped off rapidly either side (20dB down at 10Hz!)
basically i've been mucking about with the idea of blowing air over the top of a helmholtz resonator but firing it out through a t-line tuned either to the same frequency or an octave lower or higher
it's giving some interesting results but i've not tried putting one on both pipes of the cannon yet (wait till i start horn loading it that'll be fun - The Horn Loaded Holy Cannon! :D)
the biggest problem as with the cannon seems to be getting the loading right so that the cone excursion is tamed enough to make it usable yet still give a reasonable SPL
send me the pdf i'll put it up - dave at pure-filth.org |
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| angel |
As an interesting point about material containing infrasound, I submit the "Insomnia" soundtrack by Biosphere. Not the American remake of the movie, but the original Norwegian film.
Track #3 contains a recording at the coast of Norway, and apparently has not been bandwidth limited. :bigeyes:
With my own speakers, that are not capable of sensible output in the infrasonic region, you can clearly see them reaching excursion limits before the sounds of the birdcalls get to a natural level. And by visual inspection, I'd say the frequency content is in the 1-3Hz range, consistent with where the majority of the sonic energy in the sea exists.
In order to get real infrasound in a normal room, you will need to do a single pole low-boost below 5Hz, quite simply because of leakage through walls, closed windows, poor paint jobs, etc... according to a Danish university where they are currently researching the audibility of infrasound, and the effect of infrasound on humans (down to about 0.3Hz IIRC).
(In a <10sq.m. room with like 50 pcs 13" long excursion drivers on the front and back walls. Damn.) |
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| Paradise_Ice |
| quote: | Originally posted by angel
As an interesting point about material containing infrasound, I submit the "Insomnia" soundtrack by Biosphere. Not the American remake of the movie, but the original Norwegian film.
Track #3 contains a recording at the coast of Norway, and apparently has not been bandwidth limited. :bigeyes:
, I'd say the frequency content is in the 1-3Hz range, consistent with where the majority of the sonic energy in the sea exists.
In order to get real infrasound in a normal room, you will need to do a single pole low-boost below 5Hz, quite simply because of leakage through walls, closed windows, poor paint jobs, etc... according to a Danish university where they are currently researching the audibility of infrasound, and the effect of infrasound on humans (down to about 0.3Hz IIRC).
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The sea or coast has hugh infra waves, Plus whales have been known to let out a infra burst and it can sound like a cannon firing so am told,i dont know if this is true, maybe somebody can clear this up, but am told that whales can stun prey with a sonar burst that has infrawaves in it?, Water we know can transfer sound waves much better than air, some 1500 m/s and in air i think its only 330m/s but this depends on the the temp and a few other factors, its true most common music does not contain infra sound, it drains power supplies and it can sound strange, but it does at a darkness and richness that just adds to the listening pleasure,
Infrasound is still not openly talked about, as it has a dark past and i dont want to say its all bad, it can have a heeling effect if Nicola Tesla is to be believed, also some farmers say that electric wind farms have effects on there animals, it could be the sight of the wind farms or the noise or the magnetic field they project, I honest dont know! some say infra waves are just as harmful as nuclear Radiation, as the effects are the similar, once again i am not sure, this is in the realm of white Science and black Science.
I know for sure that the more low frequency energy is created the futher it travels from source, that is a fact am sure of, these waves are natural and am told even the earth has its own heart beat, Schuman resonances i believe, god why didnt i pay attention in school!
:whazzat: |
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| qwad |
:D Hi! I can almost 100% g'tee that wilmslow will not be able to help too much only to say the drivers are no longer available..... nor will they be able to supply T/S paramaters
Richard Allan "ATLAS" 18" drivers or whatever size they were a rare beast even back in the 70's when the design was published in "Hi-FI answers" one of the haymarket range of audio rags common at the time, cheers TC:devilr:
P.S; it is possible to build it with alternative drivers as the south african chap proved, [ which was fortuitious for him ] perhaps dropping him a line may ellicit a bit more info to help you........ |
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| angel |
| quote: | Originally posted by Paradise_Ice
The sea or coast has hugh infra waves, Plus whales have been known to let out a infra burst and it can sound like a cannon firing so am told,i dont know if this is true, maybe somebody can clear this up, but am told that whales can stun prey with a sonar burst that has infrawaves in it?, |
Actually, as I recall, they do not give off a sonar-like burst, but my PC is not connected to the hifi, so I couldn't possibly tell. I do know good reproduction of some whale songs will require relatively good response to about 15Hz or so..
A link to humpback whale song: http://www.oceanmammalinst.org/hmpback1.wav.
IMO, the term infrasound should be used below 14Hz, since that is where the transition between a single tone and discrete pulses occurs as far as our hearing is concerned.
| quote: | | Water we know can transfer sound waves much better than air, some 1500 m/s and in air i think its only 330m/s but this depends on the the temp and a few other factors, |
Water transfer sound waves faster. I'd doubt they transfer them better, i.e. more linearly.
As for air as a medium, it is interesting to note how many people tend to disregard the transfer characteristics of air.
| quote: | | its true most common music does not contain infra sound, it drains power supplies and it can sound strange, but it does at a darkness and richness that just adds to the listening pleasure, |
Actually, the draining of power supplies isn't as much of an issue as the possible health dangers. But those are also pretty overrated. I mean, a 24Hz tone of sufficient level and duration will induce a potentially fatal bowel condition. Most of us have systems that are easily capable of reproducing such a tone. Extending response another few octaves isn't much of an issue health-wise, IMO. What you do want, however, is a meter showing you the amount of energy below 30Hz in your room.
Anyway... as to the necessity of infrasonic reproduction in a stereo, I would argue that the system does need to be flat well beyond the audible range, since a single pole at 10Hz, like what they use with CD's, will cause significant phase shift at e.g. 40Hz.
IMO, aiming for flat response with minimal group delay to a few hertz, or even 0.1Hz, is worthwhile. Use a Linkwitz transform circuit to move the poles of a sealed enclosure to where the poles from room boundary gain are, and move the ~5Hz leakage pole down to 0.1Hz with a Q of 1/sqrt(10.5)...
On recordings that are not bandlimited, this should give incredible bass, and it doesn't require significant extra energy with normal program material.
| quote: | | I know for sure that the more low frequency energy is created the futher it travels from source, that is a fact am sure of, these waves are natural and am told even the earth has its own heart beat, Schuman resonances i believe, god why didnt i pay attention in school! |
The Schuman resonance occurs at 7.8Hz, with a tolerance of 0.3Hz depending on atmospheric conditions. Please refer to this URL: UCLA Berkeley NCEDC.
Oh, and I think it's a magnetic resonance formed in the Earth-Ionosphere cavity, from what the page says. |
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| sreten |
Hmmm..........
As with all patents its the method you can patent rather than
any intellectual principle, whether it works or not is irrelevant.
Objective evidence is simply not required for a patent, and as
such patents are not a good source of practical implementations.
Now correct me if I'm wrong but if it works as described GH would
have had many manufacturers beating a path to his door to be
able to produce a compact high efficiency HT sub down to 20Hz.
This is patently (sorry....) not the case as far as I'm aware.
His diodic electrical correction of the asymmetry of the compression
of air may work but its irrelevant. Drive unit manufactures arrange
asymmetric magnetic fields to compensate for this, simply claiming
they are ignorant of this fact in the patent is far from the truth,
but in terms of patenting the "method" such claims are simply
ignored, its only the "method" that is examined.
Again you can patent a method, even if a far superior technique
already exists, here your problem is simply selling your method.
I really can't see any advantage over bass "cannons"
and TL's or similar tuned to the relevant frequencies.
:) sreten. |
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| 7V |
| quote: | Originally posted by sreten
I really can't see any advantage over bass "cannons"
and TL's or similar tuned to the relevant frequencies. |
I'm inclined to agree with one proviso. The whole issue with bass is not how low it goes, what SPL is achieved or even the distortion levels but what volume it takes to achieve it.
My gut feeling is that I'd go with a TL but I'd really like to follow this story and learn more. I'll certainly do some experimenting when I can. |
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| sreten |
| quote: | Originally posted by 7V
I'm inclined to agree with one proviso. The whole issue with bass is not how low it goes, what SPL is achieved or even the distortion levels but what volume it takes to achieve it.
My gut feeling is that I'd go with a TL but I'd really like to follow this story and learn more. I'll certainly do some experimenting when I can. |
Certainly pursue the matter until your curiosity is satisfied.
I lost patience with the patent description when it claimed room
impedance matching only applicable to horn loading, again the
accuracy of such claims is not relevant to the patent, and such
impedance matching is often claimed of TL's.
Except for horns its all BS IMO.
I agree low bass is about volume achieved, but surely low bass
SPL capability must be considered, unless you mean different.
:) sreten. |
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| synergy |
| quote: | Originally posted by sreten
Certainly pursue the matter until your curiosity is satisfied.
I lost patience with the patent description when it claimed room
impedance matching only applicable to horn loading, again the
accuracy of such claims is not relevant to the patent, and such
impedance matching is often claimed of TL's.
Except for horns its all BS IMO.
I agree low bass is about volume achieved, but surely low bass
SPL capability must be considered, unless you mean different.
:) sreten. |
i think the SPL of low frequencies must be considered it takes 70+dB at 20Hz to even reach the threshold of hearing yet that only equates to listening to 1KHz at 7 or 8dB
however i don't believe that has to increase in the same direction below 20Hz as it then becomes more about the level needed for your body to feel its presence at level that feels comfortable with the rest of the music |
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| 7V |
| quote: | Originally posted by sreten
I agree low bass is about volume achieved, but surely low bass SPL capability must be considered, unless you mean different. |
No I don't mean different. Of course low bass SPL must be considered. |
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| Paradise_Ice |
You know the strange part is everybody makes sense!
I personally do not like bass that sticks out like a beer belly,
It should sound natural and dark, the whole point to me is (and i dont care for the patent) to get as close to the original sound! the orginal source would have had these low energy infrawaves, these get lost, Has anybody heard a true infrawave woofer in action? its not some beastly device, its basically a subwoofer with a much greater output at 5 to 23 Hz, most woofers do not have a usable output in this range, and this is why people want more bass and louder bass, IMO, bass is the most irritating, cantankerous thing to listen to if its not in proportion with the rest of the sound. This whale song is to new age for me, Maybe Mike rowland Aeolis could do something with this? As for the whales infra sound, thats not it? for all i know those whales could be drunk, I am not sure once again, but i was told whales could stun sea animals with there infra sounds, i know they could do it with a good wack of its tail too! |
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| sreten |
As far as I'm aware its Dolphins that use sound waves to
confuse their prey, as an extension of their sonar capabilities,
the whole idea of "stunning" infrasonic soundwaves in water
with practical observation seems ridiculous.
:) sreten. |
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| Paradise_Ice |
| quote: | Originally posted by sreten
As far as I'm aware its Dolphins that use sound waves to
confuse their prey, as an extension of their sonar capabilities,
the whole idea of "stunning" infrasonic soundwaves in water
with practical observation seems ridiculous.
:) sreten. |
There is so much written on marine sonar and infra wave technology, you could drown in a sea of information!
I believe your right about the confusion factor but am not talking about Dolphins, Can you imagine a whale screaming at you under water? Its very well documented that Acoustic weapons use infra sound, . A Major in the pakistan army told me about the use of beam weapons, I was so dismissive about it all, A sound weapon! very unlikly, back then in the 1990 i was not on the internet and there are few books on the subject, But the fact is you guys talk about sound levels, Now at 120 to 130 db that i can reach in the extrem range of what i do, extreme nausea and intestinal pain! I know this for a fact, its just not music at all! at 170 db of infra sound would cause blunt force truma, lucky for me i dont dabble in this range and have no interest at all but i can not back this statement up at all with any impirical say so, i think for music around 80db of infrasound is acceptable and will not cause any problems at all.
I will make a Holliman enclosure, its not that complex and it sounds like it could work. Whats the worst that could happen? |
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| sreten |
Acoustic (i.e. air) infra sound weapons have existed since they
where developed but never used by the Germans circa WW2.
The properties of sound in water and air are not remotely similar
and free exchange of concepts between the two is dangerous.
:) sreten. |
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| Paradise_Ice |
| quote: | Originally posted by sreten
Acoustic (i.e. air) infra sound weapons have existed since they
where developed but never used by the Germans circa WW2.
The properties of sound in water and air are not remotely similar
and free exchange of concepts between the two is dangerous.
:) sreten. |
I think its important to understand energy in every medium,
Water and air have obvious differences and am not confusing the two, if scientist do not talk to other scientist, its our loss, why do quantum physicist talk to buddhist monks, all knowledge is power. |
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| rolfy72 |
"Acoustic (i.e. air) infra sound weapons have existed since they
where developed but never used by the Germans circa WW2"
This may not apply to speakers but might be some insight into infrasonics!
At my place of work a lead(as in the metal)smelter/refinery we use what we call portable burners. They are run on town gas at high pressure and compressed air at 180psi. They are capable of 20ft+ long flames in open air before blowing itself out because the amount of gas/air flow.
We use these to melt lead out of our launders when they block up, launders are U shaped. The flames can go near 40ft once burner is placed in them... until the air is used.
If heard huge pa subs up close, massive db car subs, planes/jets none of them compare in the shear movement of your chest cavitiy like these burners do. You cant hear it(other than a highpressure flame sound, looks like a massive 6ft oxy flame!)but you can sure feel it move your body in a way you've proberly never felt(unless you work in this kind of industry). The whole refinery(huge shed has 6 120ft wide gantry cranes...) just shakes and vibrates... we are talking 1-2" thick steel!
It makes the sound/feel of lighting seem lame and whimpy(for comparsions sake).
But if you put the flame against a flat wall of some sort(so the flame cant blow out)the infrasonics disapear, maybe there's something in the U shape that cause's this...anyone?
Please excuse my spelling! |
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| pinkmouse |
| I'm not sure I have time to get involved in the debate, but it would be interesting to see pictures of those burners in action! |
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| Paradise_Ice |
| quote: | Originally posted by rolfy72
[BAt my place of work a lead(as in the metal)smelter/refinery we use what we call portable burners. They are run on town gas at high pressure and compressed air at 180psi. They are capable of 20ft+ long flames in open air before blowing itself out because the amount of gas/air flow.
We use these to melt lead out of our launders when they block up, launders are U shaped. The flames can go near 40ft once burner is placed in them... until the air is used.
The whole refinery(huge shed has 6 120ft wide gantry cranes...) just shakes and vibrates... we are talking 1-2" thick steel!
It makes the sound/feel of lighting seem lame and whimpy(for comparsions sake).
But if you put the flame against a flat wall of some sort(so the flame cant blow out)the infrasonics disapear, maybe there's something in the U shape that cause's this...anyone?
Please excuse my spelling! [/B] |
This is fascinating to me! what a job to have :hot:
My brother-in-law worked as a F-16 engineer and told me stories about after burners and the incredible sounds they make, i think because your in an encloused space the sound is trapped and with Jet engines the sound and energy is forced in one direction into an wide open space, am sure its similar but i have never been that close to a Jet engine! and i have never been to a lead mill! I am not sure about the U shapes effects on the sound but am sure its has a purpose, Its well known that big bush fires have infra sound and animals run well before they can even smell the fire, i know some get toasted but i dont know how animals think! Thanks for the info;) it put a smile on my face:D |
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| qi |
SYNERGY:
I love your idea about “blowing over a bottle”.
I blew over a 5 gallon glass jug recently and got some REAL DEEP BASS – much more than my mouth’s FS :D
As you may or may not know, I have a Bose Cannon tuned to ~20HZ(15’) to ~60HZ(5’) using a JBL LE14A which has an FS of 28HZ and a Q of .3
By adding this chamber tuned to 15HZ maybe I could pick up another ˝ (or so) octave of DEEP BASS?
It seems that Graham Holliman’s designs “blow over” the chamber as close as possible to the location of the driver.
Perhaps this is an area for investigation (as you mention)?
Logically, one would think that the chamber port be as close as possible to the OTHER end of the (in my case 15’) pipe – where there is SIGNIFICANT energy going by?
If we concentrate this method into a very narrow DEEB BASS range maybe we can get somewhere?
HEY – I’d love to be flat from 15HZ to 60HZ instead of 20HZ to 60HZ.
Savvy?
SRETEN:
What do you think big guy? Is there anything here? Or am I whistling dixie (as usual)... |
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| Circlotron |
| quote: | Originally posted by fragma
9. You REALLY do hear incredible sounds like mic bumps through the amp of a live recordding like Eric claptons unplugged. Song number 4, (12 or 10) on Enyas watermark, and few others...not many.
In Enya number 4, there is a sub fr undertone of around 15Hz the entire song that you cant hear on a conventional system. However, half way through the song you need to turn it down ....its too much to bear, but serves as a great demo. |
Enya number 4 has a 34.7Hz tone in it at low level; at 15-16Hz there are sounds about 36dB lower in level.
Yeah, track 10 is good for giving your non-hifi friends a surprise. Nice solid 32.064Hz bass drum. :smash:
Track 12? :confused: :dodgy: |
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| synergy |
forgive the delay other things have stopped me from working on this too much and i went on holiday for a while
however the good news is using a T-Line form this does actually appear to work
the downside being there's no way to get around the simple fact that the air needs to be moved in the first place and consequently a large driver and/or Xmax is needed
also because of the low frequencies and lack of significant loading on the driver it doesn't take much power at all to reach the excursion limits of your chosen driver
to keep the size down to practical limits i've been modelling this using a Shiva in a tapered T-Line tuned to it's Fs (the taper appears to load the driver slightly and definately helps smooth the response)
first off the response plot
blue line = TL without chamber
black line = TL with resonant chamber
green line and cross = max spl at Xmax
it's worth noting that the TL on its own brings home an 8Hz signal at 50dB that's a massive 30dB down compared to the TL with the chamber
in response to qi's query over the position it definately seems to want to be close to the driver for the widest bandwidth
position
black line = driver end
blue line = middle
green line = open end
so anybody want to venture a better driver than the shiva?
i'm thinking v. low Fs, Qts and Vas with an Xmax to die for - hows the parthenon doing? ;)
dave |
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| Coolin |
Could you show some simple drawings of the enclosures concerning the 3 placement options of driver and extra chamber?
Thanks, Coolin |
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| synergy |
no drawings i'm afraid this is all modeled in virtual space
the T-Line was tapered 1:0.2 Sd and the duct to the chamber was placed 10cm from the ends of the line with the driver not moving from it's position at the closed end
i dare say a little playing around with driver and chamber positions may yield better results but i was really after suggestions for a better driver than the shiva before i continue further (pref one i can get in the uk)
dave |
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| Konrad |
Can it bee seen as if the mass of air in the duckt is added to the driver, and the outlet duck aligned to the system somthing near Qb3 ? i think it may give an idea of how deap it can go(?)
Finaly i think that cavity resonators and their behavior regards self damping (d) is not realy somthing to aim for if you are aiming transient respons rather than freq response.
Or how abt modify the model of resistive chamber copling ?
After all the electrical feedback to the amp regarding damping must bee considered as 'lost in velosity'. After all it's blowing a big bottle tuned with a narrow bandwith resonance isnt it ? |
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| BassAwdyO |
| if someone wants to like design an version of this for a Tumult.... I'd be willing to build it and test it out:D I'm already close to flat down to 10hz with a 6cube vented box, so any more infrasound would be just that much more of an earthquake in my house. |
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| xstephanx |
I think someone should design a TL flat down to sub 10hz for an atlas 15" many reasons, heres some of them
-Cheap driver
-3litres LINEAR displacement
-much more maximum displacement due to XBL^2
-relatively low fs
-realtively low(or adjustable) QTS
- I own one, and i just loooooooooove low bass! :D
Whats the efficiency of a TL compared to a sealed box? |
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| paulspencer |
So who has actually built this thing? Paradise, BA?
A link in a recent thread on this one shows a word document which has all the dimensions for a given driver size. The design is already done. You just have to adapt it slightly for the particular mounting requirements of your driver, and make some allowances if its for a driver like the Tumult with a large surround and excursion, hence requiring some clearance to allow for its excursion. |
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| Volenti |
I'm making a trial version to suit an 8'' I have lying around (JL8w1-4), I already have a large TL that uses 4x12'' drivers so I'll have something usefull to compare it to.
I'll post pics/impressions when it's done. |
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| paulspencer |
Great, I'll be very interested to see what kind of result you get.
How are you working out the dimensions? Are you basing it on the table for the 10"? |
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| Volenti |
| quote: | Originally posted by paulspencer
Great, I'll be very interested to see what kind of result you get.
How are you working out the dimensions? Are you basing it on the table for the 10"? |
Yea with some modifications to make it modular so I can swap vents and resonator chambers ect. I want to get a "feel" for what the design is doing, mabie get a "rule of thumb" sorted out.
As I see it I should be able to compare the line with the resonator attached to the output of just the TL by it's self. |
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| paulspencer |
| Perhaps if you look into the formulas for helmholz resonators you might find something also. |
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| bibster |
Hi Volenti, and others,
Any progress here? Any first impressions?
Everytime I see this Holliman thing coming 'round, I feel like "hm... wanna try this..." but still a bit anxious to waste pennies.
Haven't got the space to place it, and I'm not sure wether my room suits this 'thing' or not. Not even sure if I have the wood skills to build it...
Read a long thread about this over at the decware forum as well, but both that one and this one sort of stopped about 2 weeks ago...
Now if someone (or more!) happend to give some (hopefully good) impressions, that might convince me....
Good luck building 'it' (And speed up the process, so I can start! :devilr: )
Paul |
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| just a guy |
Did you see the thread I started (5 - 25 hz is the thread title) to try to discuss the theory of this design and regenerate interest? There are only a couple of guys that bothered to comment at all. I think I have a decent handle on how this thing works, but of course only a single person has even commented on my ideas and he does not agree with me.
In that thread I posted a few good links to all the pertinent info I could possibly find but I did not link to the decware thread because as far as I am concerned it contains no useful information that is not already covered by the other links.
Of course there are more because this was once a commercial product, but I can only find evidence that 2 people in the world have made this box, one of them made a 10 inch version, and the other a 15. By all accounts, both were very happy with the results.
I am very confused by the seeming total lack of interest in this box. It has been around for decades but the only info I can find is what I have posted and linked to. Besides a few offhand comments no one seems to even want to discuss this design. I have only had the plans for a month or two now but I will definitely be building one as soon as possible (which unfortunately will not really be all that soon).
I am seeing claims that this box will do 5 - 25 hz with sensitivity values that rival high effieciency fullrange drivers and exceptionally low distortion. How can there be no interest in this?
Maybe there is no interest in the frequency range of 5 - 25 hz for most people. Maybe people who understand the design better than I do have considered this idea and found it to be flawed somehow and not worth the time or money. Perhaps people know of better ways to reproduce 5 hz. I have researched the possiblity of getting down to 10 hz (certainly not 5) with readily available drivers and box types and have found that meaningful SPL levels require massive driver excursion and cone area combined with massive amplifiers. Basically about $1000 to do properly (but still modestly). Although I have no actual measured numbers from the Holliman box, I do know that the 10 inch version can be made for under $100 (driver included) and it can be powered adequately with any amp you have lying around.
This seems like a very cost effective experiment in the money hungry world of infrabass and the cost would be worth the learning experience even if it didn't work.
So again, where is the interest in this design? It's like pulling teeth to even get people to discuss it. |
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| ScottG |
| quote: | Originally posted by just a guy
How can there be no interest in this?
So again, where is the interest in this design? It's like pulling teeth to even get people to discuss it. |
IMO it looks fundamentally flawed (as previously discussed and modeled). Even as a relativly low cost project - it doesn't seem to merit the time and effort to try it.
Just because 2 others have built it and like it doesn't mean that the device is actually operating as *advertised* (generally, or in a patent).
While I could well be wrong, I think that you will continue to be "pulling teeth" on this subject until decent measurements are made from a good "working" example.
This isn't to condemn the concept, but rather to say "I'll wait and see" until it objectivly peaks my interest. ;)
Do you understand now? |
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| paulspencer |
If a 10" driver could reach 95 db efficiency from 5-25 Hz and do it with accuracy, there would be a flood of interest. I think most feel it's too good to be true, and assume that it would be very inaccurate, or simply wouldn't prove to be efficient. Also many don't have a suitable room.
I wouldn't say there is no interest. I think most would like to see some results first. I'm interested to see your results and comments after you build it. |
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| Volenti |
| quote: | Originally posted by bibster
Hi Volenti, and others,
Any progress here? Any first impressions?
Everytime I see this Holliman thing coming 'round, I feel like "hm... wanna try this..." but still a bit anxious to waste pennies.
Haven't got the space to place it, and I'm not sure wether my room suits this 'thing' or not. Not even sure if I have the wood skills to build it...
Read a long thread about this over at the decware forum as well, but both that one and this one sort of stopped about 2 weeks ago...
Now if someone (or more!) happend to give some (hopefully good) impressions, that might convince me....
Good luck building 'it' (And speed up the process, so I can start! :devilr: )
Paul |
I pretty much only have one modular section left to build and mine will be ready to go, I'll post pics and impressions, good or bad, when it's done and I've had time to play with it. |
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| just a guy |
Ok, understood, Scott. But if it did actually perform as modelled here, he would not have been granted a patent (I don't think you can patent wild, unsubstantiated claims), this would not have been a commercial product, there would be no evidence whatsoever of anyone being happy with it and furthermore there should be at least one person WITH EXPERIENCE to contradict the claims. Or maybe it sucked so bad that it bombed commercially with few to no units sold and that's why there is not much information.
Either way I don't care, I'm going to at least try it. Too good to be true? Maybe but I see potential here. |
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| moray james |
you can patent just about anything, the patent office is happy to take your money for the application and the yearly dues to keep it in place. Some of the biggest piles of (stuff) that you will ever read is to be found in some patents.
You are going into this one pretty much blind and almost on your own. That's not a bad thing really. Blind in that you don't have a set established design to build. That way at least you can do what ever you think you need to do to make it work. You get to have a fresh and personal kick at this cat. There are enough folks here that will be interested in your results and most likely also want to throw their two cents into the bank if it does not work out as hoped.
Sounds like volenti has the right idea to get the max possible options from his build. You could do worse than to follow his lead. Perhaps you two could double track with each other and do some experimenting together to fast track the project? Regards Moray James. |
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| Volenti |
| quote: | Originally posted by moray james
You are going into this one pretty much blind and almost on your own. That's not a bad thing really. Blind in that you don't have a set established design to build. That way at least you can do what ever you think you need to do to make it work. You get to have a fresh and personal kick at this cat. There are enough folks here that will be interested in your results and most likely also want to throw their two cents into the bank if it does not work out as hoped.
Sounds like volenti has the right idea to get the max possible options from his build. You could do worse than to follow his lead. Perhaps you two could double track with each other and do some experimenting together to fast track the project? Regards Moray James. |
Yea I'm approaching this from the angle that I understand most, which is transmission lines. I build a line that is just long enough to sound good with music but that would be "weak" for HT in the lower end, then add the resonator to it and see what effect it has (with the ideal result of an extended bottom end), all the modular stuff just makes it quick and easy to go "now what happens if I do this..." |
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| paulspencer |
Going into it blind? I wouldn't call it that, since there is documentation describing all the sizes - you don't have to design it, just build it from the instructions.
Cost is not a huge deal. MDF is cheap, and you can use a driver you have on hand - most of us have something we could use.
For many of us, the real issue is having a room that suits. |
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| moray james |
Hey Paul: the design is decades old and a real cold potatoe at that. There are only two known accounts of people building this thing (not counting Wimslow) and with limited feedback. That is as close to blind as I want to get. Yes there are drawings to build off of. My point was that aside from the patent (which makes limited sence) there is an open playing field here. Any one who wants to play with this design and pick up where Holliman left off is free to do so. There is no common theory to have to follow. The new builder is free of the normal pressures that come from trends.
The patent tells you about the box in the drawings but not how to design one or what really makes it work, it is Holliman's theory. That and a dollar won't buy you a cup of "Joe".
So the new builder has all the options in the world to play with and that is good. I will be interested to hear of the results of any here who give this cat a kick. Regards Moray james. |
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| just a guy |
I really don't have any idea why I feel so compelled to speak up in regards to this box's (relatively unproven) merits and I will probably stop soon, but...
People are still wondering why this box can do the things people claim it can. I have said it before (maybe not in this thread) and I will say it again. It is all about the loading method. That is why Akabak cannot model it properly and why so many people don't understand what is going on here. The following excerpt is from the Decware thread. It documents a preliminary experiment that someone did with the same type of loading method. It is something everyone can try, and the people that have Akabak can try it, then model it, then compare and wonder what went wrong. This information came from 2 or 3 long posts so I editted for meaningful content. Head over to the Decware forums to see it whole.
"Try this... Using an existing sub woofer enclosure that has the driver firing into the listening space; remove the driver, and stuff the port with an old shirt or towel or something to plug it off. Extend the hook up wires about a foot or so and attach them to the driver terminals. insert the screws that held the driver in place back into thier holes until the head of the screw is approx. 9/16th above the hole in the enclosure turn the driver so that the magnet is outside the cabinet and place it upsidedown with the edge of the basket resting on the screws. Hold the driver still with your hand or use a pair of pipe clamps and a board if you like.
This is what I have done so far with experimentation. I dis assembled my KLH 10-120 sub and used 4 sets of home made sdjustable spacers to find the most effective distance between the hole the 10 inch driver was origionally mounted in and the basket with the cone firing into the hole. Essentially, I pulled out the driver, and placed it backwards over the cabinet it came in. I plugged off the origional vent, and used no other baffle for the first experiment.
The Result: most efficient spacing is a mere 9/16 inch above the hole. I can feel the vibration through the chair I'm sitting on at moderate volume, and the old fashioned metal bell alarmclock across the room starts ringing if I turn the gain past half way at 25 cycles.
I am a little worried because my ears are complaining a little bit. Maybe this isn't such a good idea? Next time I will have to wait till no one else is home and use ear plugs just in case this gets a little dangerous. "
There lies the magic of this box. It's all about the loading method. Add a couple of tapered ports for added sensitivity and lower bottom end tuning, add some velocity coupling for even more of the same, and that's it.
And finally, just to back up my opinion that this thing will be capable of getting loud, a quote from GM from another thread where I specifically asked if he would like to comment on this design.
"I researched the G-H some time ago, but can't find my notes, though in a nutshell, in theory I can get superior performance overall in a smaller bulk using a corner loaded PWT now that low Fs, high Xmax/power handling drivers and megawatt amps are available at a reasonable price. Still, a low pass filtered resonant cavity can be a 'moving' experience if you have a basement, attic, or similar size volume available to couple it to."
Now in the end, I will be building this box but I wonder how the news will be received. I will be only the third documented evidence of someone who has built it and is (likely to be) very happy with it. I don't own an SPL meter, why believe me either when the time comes? |
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| moray james |
Freddy over at the asylum posted a thread on an old Jensen design that used a similar vent loading system. The mini sub that I just posted about also uses a similar arrangement.
Don't understand why you are taking the reluctance of others to agree with you regarding this design personally. You said it yourself you will be only the third person in decades to build one of these. Ok that's great and many will be interested in your results. Everybody else could well be wrong that's possible, what do you really think?
I think that you may be sucessful in finding a way to make it better which would be great. However you may not succeed and the design may be a bust. Its a **** shoot. You are willing to give it a roll just as others are not and intitled to give it a pass. You asked for opinions but get upset when the opinions don't support what you want to believe. Build one and post about it. I am sure that there will be interest either way. You will want to build a very rigid system so MDF is not going to be in the cards. Regards Moray James. |
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| just a guy |
In the thread I started I posted my thoughts on this design. No one agreed and one person disagreed. Believe me, I'm not upset about that. I started a separate thread because in that one I wanted to discuss the possibility of slightly manipulating the tuning to suit personal taste before I build.
The reason I did not want to post those ideas here are because the thread I started assumes from the beginning that this design works while this thread has still not come to that conclusion. The only agreement I am looking for in this thread is that the Holliman type loading method - not the entire design, just the loading method - actually does work and if used properly, can be used to obtain lower than ordinary bass from a given driver at unusually high sensitivity.
After reading my last post I suppose I almost do sound upset because of a bad choice of wording that I can no longer change. So what I meant was - I will be building the box but the only measurement tools I have are signal generators and my ears. It's still only one guy's opinion in the end.
All of this is just yet another way of saying I see potential here, and I will stop saying that without proof. I agree, I do sound a bit upset in that last post and I certainly am not. |
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| moray james |
Can you explain where youre understanding and mine diverge? I see the big box cavity as a Helmholtz resonator you can establish at what frequency this volume will resonate as well as its Q and band using the speaker calculator since you have the volume and the vent opening size and can decide the cabinet wall thickness at what ever thickness you choose. Then I see what you discribe as reflex ducts as a pipe all be the the shape is modified (tapered). The reason that I see them as a pipe rather than ducts is that they couple together acoustically in the middle over the top section of the Helmholtz cabinet right where the vent is. So I dont see them (the ducts) as an extension of the Helmholtz port like a reflex vent. Both sections couple and should (as far as I can tell) act like a single pipe (of the combined length) would.
So I see the driver as the generator of the acoustic energy that excites the pipe (as I see it) which then in turn excites the resonance of the helmholtz cavity. I suppose that this process could be reversed but amounts to much the same thing. I am thinking that you want the resonant frequency of the Helmholtz resonator (which should be the lower frequency of the two systems) to be positioned at the low end (or even below the lowest resonant mode of the pipe) of the pipe's resonance to obtain the maximum extension of the rpossible resonant boost of the system.
Does this make sense to you? If not tell me where we differ. Hope that this discussion helps, looking forward to your thoughts. Regards Moray James. |
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| just a guy |
My full description of the design is in the other thread, in an attachment. I still firmly believe everything I put in there. But since there is no consensus at this point there is another way to go about this. Instead of talking about how and why, I will try "what if..." Note that I have not tried any of this yet, it's just my best guess at what might happen.
What if you took a suitably sized subwoofer, took the driver out, reversed it, and suspended it in front of it's mounting hole? (2 cubic foot sealed box for a 10 inch driver, 4 for a 12, 7 for a 15) Although I have not done it yet, I expect that there would be a huge but narrow resonant peak much lower than the box tuning/driver combination would suggest. Because of the loading method, the resonant frequency of the driver/resonator combination should be between 20 and 30 hz for the driver and box sizes we are dealing with. I would expect this narrow-band peak to swamp everything outside of it's range of resonance, and even without a baffle or external ports, to do so with incredible sensitivity and low distortion, all simply because of the loading method. In this form it would be unusable in an audio system, as it would simply be a huge narrow resonant spike lasting only a few hz with a steep rolloff on either side.
Now, what if you add a baffle for the driver and control the output by using ports, passive radiators, etc, like Holliman's examples? If you were to do a frequency sweep starting high and going down, I would expect to hear little to nothing until you got down to the resonant peak of the sealed chamber as detailed in the last paragraph, somewhere around 20 - 30 hz. But instead of being a narrow-band spike, I would expect the resonance to continue down in frequency to a point dictated by the helmholtz resonator/port (or PR) combination. Basically, the longer the port (or the lower tuned the PR) the lower the overall box's range of resonance will extend. I would expect everything outside of this range of resonance to be rolling off at a very steep rate.
That is what I think should happen, but again, I haven't tested any of it. If it works out like that, the how and why is not so important. If this much is true, it allows for a bit of tweaking for the upper and lower frequency cutoff points. |
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| moray james |
I wanted to mail this to you directly but your mail is blocked. I think that you may well find some interesting information in this patent application. The company has been around for a good number of years and has substantial financial backing. They actually produce a variety of different models. I will assume that this idea works as they have been building and selling them for some time. You can see a review at 6 moons. The application below is the second refinement of the concept so work has been on going. You may find some techniques to shrink your Holliman design in the application. As a diy project I see this as far more practical. I should think that you could either scale the design if you wanted but a better idea might be to use four or eight such small units dispersed through out your room to achieve better controll of room modes and still keep the volume impact almost invisable.
Will try to come up with a reasonable reply as soon as i can figure one out. Best regards Moray James.
United States Patent Application 20040251079
Kind Code A1
Plummer, Jan Princeton December 16, 2004
Inventors: Plummer, Jan Princeton; (Marietta, GA)
Correspondence Name and Address: JAN P. PLUMMER
341 ENGLAND PL NE.
MARIETTA
GA
30066
US
Serial No.: 709538
Series Code: 10
Filed: May 12, 2004
U.S. Current Class: 181/199; 181/156
U.S. Class at Publication: 181/199; 181/156
Intern'l Class: A47B 081/06
[0036] DIRECT COUPLED LOW FREQUENCY ONLY APPLICATIONS-Conventional loudspeakers need large diaphragm areas and/or high mass to produce low frequencies while attaining high efficiency in the process. The current processes for bass reproduction are inherently efficient because they operate the driver at and near its' resonant frequency but this is also the Achilles' heel for sound quality. Resonance is the number one enemy of a finished sound system although the parameter is involved with the execution of any speaker system. The DC EATL 5 mode of operation will allow a very small driver to produce low bass frequencies at low to moderate efficiencies. When a 3" driver is made capable of producing very low frequencies at a useful level then efficiency isn't a proper term to characterize its' performance.
[0037] FIG. 5 represents the application of the EATL5 in conjunction with a dynamic driver 41 for the purpose of generating very low frequencies only and is called the Direct Coupled DC EATL 5. The EATL construction is very similar to the IDC with the exception of a larger throat/mouth opening 6 equal to the driver diameter and compression plug 12 located immediately in front of the driver 41. The EATL 5 is Directly Coupled (DC) to the driver 41 with minimum area air volume in chamber 10 between the driver and the throat/mouth 6 of the EATL 5. The driver is mounted with front facing the EATL5 mouth 6 so as to create a high compression chamber 10 for driver loading. In this mode the driver 41 is compression loaded so a compression plug 12 is used to help direct wave motion into the EATL 5 and to minimize air turbulence at the throat/mouth 6 of the EATL5 and to establish the correct throat/mouth 6 area for the EATL5. DC coupling places the driver 41 completely under the influence of the EATL5 and it will follow the frequency pattern it establishes. The ADTM 4 establishes delay of the waves through depth migration thus allowing a wide DSW bandwidth. The higher low frequencies above driver 41 resonance are not effected as readily by the cellular structure and will sustain constant pressure in the EATL 5 before depth migration. This can be seen in FIGS. 13C and 14D. The frequency response curve FIG. 13C represents the driver 41 output of a DC driver and EATL5 only and it can be seen that the frequency response shows a 12 db/oct falling output from the driver 41 resonance frequency and frequency irregularities above driver resonance. This represents a constant high positive pressure on the DD 3 relative to frequency and a dynamic pressure much greater than atmospheric pressure for all frequencies in the systems bandwidth. When measured at 100 Hz this signal at the DD3 is 40 db greater than that at the mouth of the port 17 when it is added. This output curve represents the actual output that the driver 41 will deliver with the positive pressure applied to the DD 3 from the EATL 5 | | | |
