cool - if really plays then I might like them as sub for my K12
here's Exemplar's pick of sub for Altec back some years ago poked into a corner (its tuned lower and boosted)
http://img175.imageshack.us/img175/720/a7k15bz2.jpg
here's Exemplar's pick of sub for Altec back some years ago poked into a corner (its tuned lower and boosted)
http://img175.imageshack.us/img175/720/a7k15bz2.jpg
I just made the 10"version as stated in the 'holliman doc' that floats on the net.TwisterZ said:
Overall INSIDE width: 32cm
Resonator: Trapezium shaped, 70.9cm bottom, 78.1 cm. top, 27.6 cm sides.
Chamfered hole is 10cm diameter ON TOP (inside the resonator it's larger, due to the 45 deg. chamfer (I just cut it with a jigsaw set at 45 deg.)
Overall width: 88.1 cm
'Little hole in thin layer just underneat the speaker' is 50mm
'Height' between the baflle and the resonator: 30mm.
I did NOT put the 'standing wave inserts' in the resonator (yet?): I think the resonator is to small for any wave in it's bandwidth... They'll help for strength, though...
Ow, yes, I modified the driver a bit (In a rather nasty way
) I glued some heavy nuts on it, to increase the Mms Here's a little drawing I just made to show how I measured: I placed the box as showed on a stool (45 cm. high) and put the mic in the spot 'X'...
More to come!
Paul
Attachments
TwisterZ, just wondering, did you see the thread I started on this topic? http://www.diyaudio.com/forums/showthread.php?s=&threadid=88593
There are three links right at the beginning, one of them is for the doc with the full plans that Bibster used. It is the second link. Also included is a chart showing exact measurements of each piece used. It should answer all questions concerning his build.
By the way, what effect does the taper in port x1 have on your caculations, if any, or is it just the overall length that you are taking into consideration?
There are three links right at the beginning, one of them is for the doc with the full plans that Bibster used. It is the second link. Also included is a chart showing exact measurements of each piece used. It should answer all questions concerning his build.
By the way, what effect does the taper in port x1 have on your caculations, if any, or is it just the overall length that you are taking into consideration?
Thanx just a guy that did help
I love all the conversion neccessery
inches to meters volume and area calculations 
IMO the taper is to give the port a zero length like the body of a guitar or violin (See post #116 for the link). The calculation requires an adjustment for edge effect, Multiply port radius by 1.7 for the effective port length. Then add X1 length for the other end of the bandpass enhanced by the design.
Question to ALL
Should I post my findings or wait untill we have measurments from Bibster?
Bibster, if you could do measurments from 10Hz to 100Hz I think we could see if there is a band that is boosted by this design.
I love all the conversion neccessery
inches to meters volume and area calculations IMO the taper is to give the port a zero length like the body of a guitar or violin (See post #116 for the link). The calculation requires an adjustment for edge effect, Multiply port radius by 1.7 for the effective port length. Then add X1 length for the other end of the bandpass enhanced by the design.
Question to ALL
Should I post my findings or wait untill we have measurments from Bibster?
Bibster, if you could do measurments from 10Hz to 100Hz I think we could see if there is a band that is boosted by this design.
I was only wondering about port X1. I assume you are just calculating based on the length. But what about taper rate? Does this enter into your calculations? If not, what taper rate do you think is optimal? Or maybe the taper rate is not so important? The patent says the port X1 should be as long as possible with a minimum of taper. Just wondering how you decided on the taper in your drawing.
OT
A bit Off-Topic, but...
Whatever happend to Mr. Holliman?
The patent is filed 1978, so I'd say he might still be around... Maybe we should get a hold of him, show him the world's renewed interrest in his invention, and he might give us a hand, ideas, help, disencouragement (HE should know if it's a non functional device!)
Anyone heard of him, lately? (I've found a review of some surround mic, referencing some Mr. Graham Holliman here: http://decibel.ch/article_db.php?sid=385 )
Just some thoughts, Paul
A bit Off-Topic, but...
Whatever happend to Mr. Holliman?
The patent is filed 1978, so I'd say he might still be around... Maybe we should get a hold of him, show him the world's renewed interrest in his invention, and he might give us a hand, ideas, help, disencouragement (HE should know if it's a non functional device!)
Anyone heard of him, lately? (I've found a review of some surround mic, referencing some Mr. Graham Holliman here: http://decibel.ch/article_db.php?sid=385 )
Just some thoughts, Paul
That might be a good source of information, I actually caught myself wondering once if he was still around... Anyways there is nothing at all wrong with your english skills guys. I've had no problems at all reading any of the posts in this thread.
There may be a couple of potential problems with contacting him. I noticed in a recent municipal election in my area that some people that had been dead 20 years are still registered to vote. Government records can be useless sometimes, he could be somewhere else or nowhere at all. I suppose the yellow pages are usually more up to date, depends on how old the book is, I guess. But still no guarantee even if it's this year's book. My grandfather died decades ago but his wife has never changed the billing records. The phone records and bills are all still in his name (and the tv guide, etc, etc. My dead grandfather gets more mail than I do). But he could be there, of course.
Another issue could be postal mail. I'm not sure how fast international mail goes, but I'm guessing it's not quick. Give time for delivery, reception, a quick read and a return reply (if you are lucky) and I'm guessing it will be at least a month.
Finally, I'm not sure he will be helpful at all. Just looking back over this thread at the awful things people have been saying about this invention would be very hurtful to the inventor. I'm guessing he's been dealing with this attitude since he released his invention. Let's recap - "fundamentally flawed", "pipe dream", "myth" - would you want to help after listening to that for the last 30 years?
If you still think it's a good idea and you want to try it out, I will help in any way I can, but your english is actually better than most people living in primarily english speaking countries.
There may be a couple of potential problems with contacting him. I noticed in a recent municipal election in my area that some people that had been dead 20 years are still registered to vote. Government records can be useless sometimes, he could be somewhere else or nowhere at all. I suppose the yellow pages are usually more up to date, depends on how old the book is, I guess. But still no guarantee even if it's this year's book. My grandfather died decades ago but his wife has never changed the billing records. The phone records and bills are all still in his name (and the tv guide, etc, etc. My dead grandfather gets more mail than I do). But he could be there, of course.
Another issue could be postal mail. I'm not sure how fast international mail goes, but I'm guessing it's not quick. Give time for delivery, reception, a quick read and a return reply (if you are lucky) and I'm guessing it will be at least a month.
Finally, I'm not sure he will be helpful at all. Just looking back over this thread at the awful things people have been saying about this invention would be very hurtful to the inventor. I'm guessing he's been dealing with this attitude since he released his invention. Let's recap - "fundamentally flawed", "pipe dream", "myth" - would you want to help after listening to that for the last 30 years?
If you still think it's a good idea and you want to try it out, I will help in any way I can, but your english is actually better than most people living in primarily english speaking countries.
I agree, nothing wrong with your english, but what do I know about english, I'm from California.
How can you be in 2 places at once when your not anywhere at all. (Firesign Theatre)
Something I've been thinking about since this forum started is that when this was designed it was very difficult to correct Phase & Delay issues. We now have very effective and easy to use digital processors that can correct for problems that must have seemed insurmountable in the late 70's & early 80's.
J.A.G. you give the man little credit...
if you have Mr. Holliman's address send him a note. My guess is that he would be happy to hear of the interest and experimentation going on. Remember that he had to go through all this himself and then again to defend his patent application.
While Mr Holliman may have some considerable insight I fear that he will have little to build upon. After 3o years of almost zero success and no commercial attempts to pick up on the idea after the patent had expired do you really expect that this will fly?
There are some very sharpe knives in the DIY Audio drawer here and they have not shown any interest in this. I think that there are good reasons. Just looking at the patent shows that the inventor was not able to explain (understand) the working mechanism of his design. That is clear. Not to say don't try but don't mortgage your house on the concept.
One of the inmates here posted some time ago a link to a site with acoustic instruments that can generate infra sonic frequencies. I am at a los to understand how they do what they do given their physical size but they do. I would think that the best chance of making headway with this kind of project would be to inlist an organ designer with some spare time and/or personal interest. That person should have all the necessary knowledge to figure up from down in this mistery box if anyone can. Holliman had a long time to try. Take up the torch J.A.G. Graham must be tired by now. Regards Moray James.
if you have Mr. Holliman's address send him a note. My guess is that he would be happy to hear of the interest and experimentation going on. Remember that he had to go through all this himself and then again to defend his patent application.
While Mr Holliman may have some considerable insight I fear that he will have little to build upon. After 3o years of almost zero success and no commercial attempts to pick up on the idea after the patent had expired do you really expect that this will fly?
There are some very sharpe knives in the DIY Audio drawer here and they have not shown any interest in this. I think that there are good reasons. Just looking at the patent shows that the inventor was not able to explain (understand) the working mechanism of his design. That is clear. Not to say don't try but don't mortgage your house on the concept.
One of the inmates here posted some time ago a link to a site with acoustic instruments that can generate infra sonic frequencies. I am at a los to understand how they do what they do given their physical size but they do. I would think that the best chance of making headway with this kind of project would be to inlist an organ designer with some spare time and/or personal interest. That person should have all the necessary knowledge to figure up from down in this mistery box if anyone can. Holliman had a long time to try. Take up the torch J.A.G. Graham must be tired by now. Regards Moray James.
I don't really know how you can say he didn't understand what was going on in his design. Some of the patent information is unclear and badly written but it contains the basis of theory we are using to test and elaborate on the original. The fact that there are 3 different size options, and a random driver provides favorable (if not perfect) results shows that the designer had great understanding of what he was doing.
TwisterZ is currently taking the theory to the next step and predicting (very accurately, I believe) how the box will respond with the use of readily available resonator calculators. I'm not sure Bibster's box has quite the range predicted, but it's definitely in the ballpark.
I think the big question now is appropriate driver parameters. Have you listened to the wav file? It gets louder as it goes lower, just as advertised. I think a lower q driver will control the situation and make it not quite SO much louder as it gets lower.
Definitely on the right track here.
TwisterZ is currently taking the theory to the next step and predicting (very accurately, I believe) how the box will respond with the use of readily available resonator calculators. I'm not sure Bibster's box has quite the range predicted, but it's definitely in the ballpark.
I think the big question now is appropriate driver parameters. Have you listened to the wav file? It gets louder as it goes lower, just as advertised. I think a lower q driver will control the situation and make it not quite SO much louder as it gets lower.
Definitely on the right track here.
why would I say that?
well Graham did not understand the workings of the design well enough to have sold what would have been a marketable design and produce it should it have worked. So he showed three different sized versions? As far as I know the only people to ever show interest were Wimlow Audio. No known record of kits being sold and as far as I know (outside of Graham) only two units made world wide. I think that tell a story all by itself.
I am sure that there are all kinds of reasons why the design never flew aside from not working. This would not be the first patented idea that did not work either. I would be interested to read Graham's account of the story. It would make for interesting reading.
You are aware that I hold doubts about the design but I remain open and interested never the less. I think that your suggestion that a low Qt driver is needed is probably going in the wrong direction. With a resonant system such as this I would have thought that you would need to use a high Q driver. Since the system cannot excit itself the driver has to input some ultra low frequency energy to get it up and running. A high Qt driver would at least have a hump in response at roll off. The bigger the hump the greater the level of very low frequency information there would be. Given the drivers of the day most 15 inch units would not provide much energy below 25-30 Hz. It would seem logical to me that the more hump in the response at roll off the better to extend response at the very low frequencies desired.
In practicle terms how far below driver Fs do you think a resonant system can be tuned and be expected to work? Do you see this system as a kind of infra sonic whissle which only requires an air pump to blow it into action? If that is the case then why bother using a dynamic driver? Why not use a fan or linear motor to pump air into it? I just do not see any tangible evidence that Graham had any idea as to how this device was to made to work. Perhaps what it is that has been discribed as infra sonic bass reproduction is actually only harmonics being modulated by lower frequency tones at much reduced levels. i don't know. Maybe Graham does? Regards Moray James.
Ps: make sure that the amp that you use actually has a minus 3 db point of below 3Hz. That in itself might provide one reson for lack of interest. Not many amps are flat to anywhere near 3 Hz..
well Graham did not understand the workings of the design well enough to have sold what would have been a marketable design and produce it should it have worked. So he showed three different sized versions? As far as I know the only people to ever show interest were Wimlow Audio. No known record of kits being sold and as far as I know (outside of Graham) only two units made world wide. I think that tell a story all by itself.
I am sure that there are all kinds of reasons why the design never flew aside from not working. This would not be the first patented idea that did not work either. I would be interested to read Graham's account of the story. It would make for interesting reading.
You are aware that I hold doubts about the design but I remain open and interested never the less. I think that your suggestion that a low Qt driver is needed is probably going in the wrong direction. With a resonant system such as this I would have thought that you would need to use a high Q driver. Since the system cannot excit itself the driver has to input some ultra low frequency energy to get it up and running. A high Qt driver would at least have a hump in response at roll off. The bigger the hump the greater the level of very low frequency information there would be. Given the drivers of the day most 15 inch units would not provide much energy below 25-30 Hz. It would seem logical to me that the more hump in the response at roll off the better to extend response at the very low frequencies desired.
In practicle terms how far below driver Fs do you think a resonant system can be tuned and be expected to work? Do you see this system as a kind of infra sonic whissle which only requires an air pump to blow it into action? If that is the case then why bother using a dynamic driver? Why not use a fan or linear motor to pump air into it? I just do not see any tangible evidence that Graham had any idea as to how this device was to made to work. Perhaps what it is that has been discribed as infra sonic bass reproduction is actually only harmonics being modulated by lower frequency tones at much reduced levels. i don't know. Maybe Graham does? Regards Moray James.
Ps: make sure that the amp that you use actually has a minus 3 db point of below 3Hz. That in itself might provide one reson for lack of interest. Not many amps are flat to anywhere near 3 Hz..
Moray
I think we are all dancing around the same point, the equipment of the day 30+ years ago would have made this design difficult to prove as a marketable product. Also Mr. Graham would not be the first person with a great idea who couldn't sell Ice Water in the desert.
Just because it hasn't found its way to the market doesn't mean it doesn't work, also most of the industry of the day were trying to convince themselves and the rest of us that,
A) we can't hear below 20Hz
B) If the room isn't 64F feet long the sound then you can't hear the sounds below that wavelength
C) There isn't any music below that Frequency, need I continue.
We have heard plenty of reasons over the years not to go there yet here we all are building home theaters that can produce sounds well below 10Hz and finding plenty of source material to show off our Subs, Tap that tank Darla.
Now that Bibster has a working unit we can evaluate its responce and see if we can improve on it with todays equipment. Who knows it just might work
your getting sleeeeppppyyy
I think we are all dancing around the same point, the equipment of the day 30+ years ago would have made this design difficult to prove as a marketable product. Also Mr. Graham would not be the first person with a great idea who couldn't sell Ice Water in the desert.
Just because it hasn't found its way to the market doesn't mean it doesn't work, also most of the industry of the day were trying to convince themselves and the rest of us that,A) we can't hear below 20Hz
B) If the room isn't 64F feet long the sound then you can't hear the sounds below that wavelength
C) There isn't any music below that Frequency, need I continue.
We have heard plenty of reasons over the years not to go there yet here we all are building home theaters that can produce sounds well below 10Hz and finding plenty of source material to show off our Subs, Tap that tank Darla.
Now that Bibster has a working unit we can evaluate its responce and see if we can improve on it with todays equipment. Who knows it just might work
your getting sleeeeppppyyy
I like to see graphs indoor and outdoors including harmonics plus impedance plots
Rob made an interpretation which IIRC didn't go out of the gap at 1KW input - question - did it do something out of the ordinary? - apparently it had some output to around 15hz
http://img140.imageshack.us/img140/6987/robvcsubst0.jpg
http://img239.imageshack.us/img239/4554/subthroathn8.jpg
http://img45.imageshack.us/img45/2900/subfold1vb1.jpg
http://img140.imageshack.us/img140/4430/robvelsideviewxn1.jpg
one snippet by Rob
"The drive slot can be chocked up to reduce its xsection, i've found this necessary too keep the speaker within sensible excursion limits when doing 20hz at over 1KW. reducing the xsection of the drive slot actually enhances the velocity coupling, but to a limit, once its too small it impedes the speaker too much"
Rob made an interpretation which IIRC didn't go out of the gap at 1KW input - question - did it do something out of the ordinary? - apparently it had some output to around 15hz
http://img140.imageshack.us/img140/6987/robvcsubst0.jpg
http://img239.imageshack.us/img239/4554/subthroathn8.jpg
http://img45.imageshack.us/img45/2900/subfold1vb1.jpg
http://img140.imageshack.us/img140/4430/robvelsideviewxn1.jpg
one snippet by Rob
"The drive slot can be chocked up to reduce its xsection, i've found this necessary too keep the speaker within sensible excursion limits when doing 20hz at over 1KW. reducing the xsection of the drive slot actually enhances the velocity coupling, but to a limit, once its too small it impedes the speaker too much"