Thanks Tinitus,
Such magnets assembled together, is one (but giant) NEO 8" toroid magnet magnetized by thick. I saw, it's used I can maybe to say often in magnet motor construction similar like in most used ceramic toroid magnet motors. There pole pieces is logically something thicker, but not so much like I expected, because they probably wanted to push even something higher magnetic flux in gap
for tweeter, midrange applications, professional drivers ... But question is - how much higher flux, because also, iron just have his saturation, so for real good utilization of such strong NEO magnets with SO BIG pole spaces - pole pieces need to be much thicker.Maybe I wasn't interested for such magnet construction in woofers, because of not more thick pole pieces there - shorter magnet gap, at least not like in radial magnetized motors (see: B-Hive Motor, some Vifa NEO woofers, or Critical Mass UL12). Such radial and similar constructions is just WINNERS for long linear cone excursion, with of course underhung voice coil like Spatz mentioned.
On the beginning I mentioned for good application and smaller box example B&W PV1, because of anyway their the best acoustical approach. PV1 appeared before almost 5-6 years with amazing results, but also, although NEO magnets appeared widely before more than 15. But before only some time , B&W begin to use some their NEO motor with long gap in woofers. If they will put in PV1 such motors instead classical ceramic, they will obviously get even much better result. So at least in general, we people are - too lazy.
I can really to agree with all you mentioned in your post, but here is not question about midrange frequencies, unless you maybe think about some woofer mid band.
Attachments
Thank you very much Neo Dan!
Yes, your simulation thumbs show exactly what I think. But there also is possible for sure in such magnet construction to push something stronger field with also longer gap , disregard whether than iron pole pieces will be enough fat for some the best (better) optimum result.
Best regards!
Peter
Yes, your simulation thumbs show exactly what I think. But there also is possible for sure in such magnet construction to push something stronger field with also longer gap
, disregard whether than iron pole pieces will be enough fat for some the best (better) optimum result.Best regards!
Peter
Also in connection with your mentioned: DIYCable.com : Intro » Home » Exodus Subwoofers ».
There is attempt to get longer gap, but this design have some some contradictories. Top pole piece is double thicker than back. By magnet construction rules, boot of them should be with same optimized thickness, to reach biggest magnetic flux in gap. By picture of this driver I can see that back pole piece have already optimized thickness for such ceramic magnet. With double thicker top pole piece, they got also homogeneous magnetic field in gap, but not so strong like with same thickness. Result is something better linearity in lower frequencies (with limited linearity when power is increased), but also with something complete lower SPL. So in some definitive woofer magnet solution, pot cased radial NEO is real winner.
There is attempt to get longer gap, but this design have some some contradictories. Top pole piece is double thicker than back. By magnet construction rules, boot of them should be with same optimized thickness, to reach biggest magnetic flux in gap. By picture of this driver I can see that back pole piece have already optimized thickness for such ceramic magnet. With double thicker top pole piece, they got also homogeneous magnetic field in gap, but not so strong like with same thickness. Result is something better linearity in lower frequencies (with limited linearity when power is increased), but also with something complete lower SPL. So in some definitive woofer magnet solution, pot cased radial NEO is real winner.
Thanks Bear!
Of course, this design should be with many, but carefully made compromises. With such approach, but first of all with properly assembled magnet motor many of problems you mentioned will be very solved.
About driver, I am something worried to find some appropriate surround, also spider, but maybe driver will be without basket, I will see.
I would maybe like to apologize to some of you here on Diyaudio because I try to use some easier language than engineering. I don't like to use such or any kind of not enough clear language. If we like to use so many "subtle" phrases, abbreviations that can means we like just to show how we are experts and big guys. But this very often means opposite thing, because many persons on this way like to hide his wrong and shallow understanding, what anyway is not useful specially here on DIY pages.
For driver I have some ideas like I said, but please I need more some good recommendations about box if someone have. :-(
Best regards!
Peter
I had such thinking before, but do you can to explain more concrete about your ideas?
I heard that with some Isobaric 4th Order Bandpass system (with two drivers) is possible to get much smaller box than with ordinarry 4th Order Bandpass (one driver).
Also I mentioned on the beginning very nice example - Bowers & Wilkins PV1 subwoofer. PV1 is only around 15 liter sealed box, with two 8" drives, but mounted on opposite sides of box. Once I heard pretty low and strong sound from similar construction with two 12", but small. It is obviously sealed, but not ordinarry. I have not exeriences nor ideas about such kind of boxes, about calculations of their volumes, shapes.
Also, such solutions with two speakers here can be favorable because of practically double higher power capacity than with only one.
Also I mentioned on the beginning very nice example - Bowers & Wilkins PV1 subwoofer. PV1 is only around 15 liter sealed box, with two 8" drives, but mounted on opposite sides of box. Once I heard pretty low and strong sound from similar construction with two 12", but small. It is obviously sealed, but not ordinarry. I have not exeriences nor ideas about such kind of boxes, about calculations of their volumes, shapes.
Also, such solutions with two speakers here can be favorable because of practically double higher power capacity than with only one.
Nooo problem!
With proper swing of arm, you should just to say - Neodymium crazyyyy!!!!
Care about pronounce!!! (Hogsworth secret!!!)
You started out with this post.
It appears your knowledge of how drivers and enclosures interact to form a system is very limited. You'd do far better than getting advice from "enthusiastic, but serious and honest audio fanatics" by taking some courses in physics and mathematics to study how sound is propagated and how these devices work. The Thiel Small parameters are a cookbook shorthand for using Newton's second law of motion as applied to forced oscillation. IMO if you study and understand Newton's second law, you have a figthing chance of building something useful....after you understand how systems other people built work and why they perform the way they do. All of the enthusiasm in the world is not a substitute for knowledge and no matter how much time, energy, and money you spend on your "dream" it won't come true unless it is directed by an understanding of how things work so that you can engineer them to do what you want them to.
In case you are unaware of it, you have an exceedingly difficult benchmark to beat using technology that is now well over 40 years old. I am referring to original Bose 901, Series I and II and its original commercial sound reinforcement counterpart 802. These sealed systems used nine 4" 30 watt RMS CTS drivers in a sealed enclosure of about 1 cubic foot. Their aggregate raditating area are the equivalent of a 14" woofer. Their signal equalizer provided only half the required 12 db per octave boost below resonance to compensate for their linear falloff and they had other fatal shortcomings. But for whatever they did wrong, one thing they could do right with sufficient amplifier power was to produce tones as low as 23 hz at moderate SPLs and 26 hz at higher SPLs with only 10% THD. This required around 300 wpc. Multiple pairs could do the same of course at higher SPLs. Starting with Series III, Bose abandoned its acoustic suspensiion design and opted for a ported design which sacrificed the bottom octave. You can buy specimens of the original 901 and series II on e-bay for experimentation usually for about $200 to $250 plus shipping however you need the equalizer which is often missing and you will have to provide further equalization to get it to work optimally.
With modern drivers you can certainly beat that performance but you will have to really know what you are doing. Bose was a professor of mathematics, electrical engineering, and acoustics at MIT. He built a billion dollar a year privately owned company largely around the sales of this product and cheaper variants at least initially. He was also among the early innovators in modest sub/satellite systems along with Cambridge Soundworks also in Massachusetts.
It appears your knowledge of how drivers and enclosures interact to form a system is very limited. You'd do far better than getting advice from "enthusiastic, but serious and honest audio fanatics" by taking some courses in physics and mathematics to study how sound is propagated and how these devices work. The Thiel Small parameters are a cookbook shorthand for using Newton's second law of motion as applied to forced oscillation. IMO if you study and understand Newton's second law, you have a figthing chance of building something useful....after you understand how systems other people built work and why they perform the way they do. All of the enthusiasm in the world is not a substitute for knowledge and no matter how much time, energy, and money you spend on your "dream" it won't come true unless it is directed by an understanding of how things work so that you can engineer them to do what you want them to.
In case you are unaware of it, you have an exceedingly difficult benchmark to beat using technology that is now well over 40 years old. I am referring to original Bose 901, Series I and II and its original commercial sound reinforcement counterpart 802. These sealed systems used nine 4" 30 watt RMS CTS drivers in a sealed enclosure of about 1 cubic foot. Their aggregate raditating area are the equivalent of a 14" woofer. Their signal equalizer provided only half the required 12 db per octave boost below resonance to compensate for their linear falloff and they had other fatal shortcomings. But for whatever they did wrong, one thing they could do right with sufficient amplifier power was to produce tones as low as 23 hz at moderate SPLs and 26 hz at higher SPLs with only 10% THD. This required around 300 wpc. Multiple pairs could do the same of course at higher SPLs. Starting with Series III, Bose abandoned its acoustic suspensiion design and opted for a ported design which sacrificed the bottom octave. You can buy specimens of the original 901 and series II on e-bay for experimentation usually for about $200 to $250 plus shipping however you need the equalizer which is often missing and you will have to provide further equalization to get it to work optimally.
With modern drivers you can certainly beat that performance but you will have to really know what you are doing. Bose was a professor of mathematics, electrical engineering, and acoustics at MIT. He built a billion dollar a year privately owned company largely around the sales of this product and cheaper variants at least initially. He was also among the early innovators in modest sub/satellite systems along with Cambridge Soundworks also in Massachusetts.
Thanks Soundminded and to all including those whose posts have been removed!
I started this thread with idea that we on Diyaudio can friendly to share interesting ideas more in cool simply joking mood than on dry way. But I am sorry if I disturbed anyone on any way, and please forgive me. I can not to know what any of you can to think about own knowledge, but I think about myself that anyway my knowledge is always limited. So, that can not be topic of this thread, here at all.
By my school I am musician, violoncellist, also I play very passionated guitars, but in parallel I am also engaged naturally (at least for me) in audio equipments specially speakers over 30 years. Like musician I have one kind of here known like - absolute hearing (I don't know how exactly to say on English). Next to the respect to many of known theoretic knowledge about speakers and acoustic, this is one of my very main approach to the speakers. So, really I like to use Thiele Small calculations most in cases when I need more to check in forward only SOME of important buildings details to me.
Yes I make speaker drivers what I need, and after so many years of engagement I have my own moving voice coil technology and others with increasing power capacity of (specially bas) speakers at least few hundred % without change of many other characteristic, compared with practically any speaker on the world. So I not need ever to use almost anything than my drivers, and also I like how B&W do because of their detailed purest acoustic and some other approaches in dynamic speakers.
With respect to all others, if you wanted to know so much - that's was about my speaker engagement if you can to understand and believe. I wanted, God gave me like to all of us, but this is my way.
I any of you want friendly to criticize me, please do that, but please once begin with something CONCRETE and PRACTICAL specially about my questions. What is the use if many of you just criticize my knowledge if can not to say anything concrete when I already asked such questions? I am sorry if my title of this thread maybe looking to some of you too much, but today exist anyway so many very nice smaller commercial subwoofer designs, and I just wanted to move at least something forward in this field. Big wonders and secrets can be about topics why and how we exist at all, but where are so big philosophy and wanders just about speakers?
Bose 901 and others his similar speakers have of course one of the closest approaches to this design, but today is possible to go forward first of all with new NEO magnet motor designs like I mentioned here already many times.
Best regards to all of you!
Thanks Soundminded and to all including those whose posts have been removed!
I started this thread with idea that we on Diyaudio can friendly to share interesting ideas more in cool simply joking mood than on dry way. But I am sorry if I disturbed anyone on any way, and please forgive me. I can not to know what any of you can to think about own knowledge, but I think about myself that anyway my knowledge is always limited. So, that can not be topic of this thread, here at all.
By my school I am musician, violoncellist, also I play very passionated guitars, but in parallel I am also engaged naturally (at least for me) in audio equipments specially speakers over 30 years. Like musician I have one kind of here known like - absolute hearing (I don't know how exactly to say on English). Next to the respect to many of known theoretic knowledge about speakers and acoustic, this is one of my very main approach to the speakers. So, really I like to use Thiele Small calculations most in cases when I need more to check in forward only SOME of important buildings details to me.
Yes I make speaker drivers what I need, and after so many years of engagement I have my own moving voice coil technology and others with increasing power capacity of (specially bas) speakers at least few hundred % without change of many other characteristic, compared with practically any speaker on the world. So I not need ever to use almost anything than my drivers, and also I like how B&W do because of their detailed purest acoustic and some other approaches in dynamic speakers.
With respect to all others, if you wanted to know so much - that's was about my speaker engagement if you can to understand and believe. I wanted, God gave me like to all of us, but this is my way.
I any of you want friendly to criticize me, please do that, but please once begin with something CONCRETE and PRACTICAL specially about my questions. What is the use if many of you just criticize my knowledge if can not to say anything concrete when I already asked such questions? I am sorry if my title of this thread maybe looking to some of you too much, but today exist anyway so many very nice smaller commercial subwoofer designs, and I just wanted to move at least something forward in this field. Big wonders and secrets can be about topics why and how we exist at all, but where are so big philosophy and wanders just about speakers?
Bose 901 and others his similar speakers have of course one of the closest approaches to this design, but today is possible to go forward first of all with new NEO magnet motor designs like I mentioned here already many times.
Best regards to all of you!
It is not appropriate to become defensive towards people who have given you their honest opinion and best advice, even if you don't like it. Being open and honest in not meant to be offensive.
Enthusiasm is a good start because it means there is motivation but that is not enough. You have to know the rules of the game before you can win. That means you have to know how things work in the real world, not just on paper. Most successes come after many trials and failures. You are also competing against other people who have at their disposal and have spent a great deal of time, money, and expert knowedge. That is not to say you can't beat them at their own game but it does mean that if you want to win in their league, you will have to beat their money with your brains which means acquisition of knowledge you don't have yet. If it were easy, it would have been done already. Before Stravinsky could write Le Sacre du Printemps he had to learn Mozart, Bach, and Beethoven. Before Einstein could invent relativity he had to understand Newton. Wanting something badly enough to do it means you have to expend the time and effort to learn. There is no easy path to get there.
"Like musician I have one kind of here known like - absolute hearing (I don't know how exactly to say on English)."
What you are probaby referring to is what we call "absolute perfect pitch." It's an inherited trait. Most of us have "perfect relative pitch" which is also inherited. It means we can recognize intervals and when a tone is sharp or flat. Perfect absolute pitch knows what key it is too. I've met people like that. It's realtively rare here but it is hardly unknown.
Absolute pitch - Wikipedia, the free encyclopedia
Good luck in your efforts.
hello i agree with you that T/S has made the design process to cook book recipe, i am reading thiele paper and it seems it is designed for electrical circuits purpose could you refer me some source to understand more of the physics of how speakers operates i wanna understand how changing the component value and the physics are affected not some numbers. thanks
Hi,
FWIW of you want to build a small powerful subwoofer use two of these :
MCM Audio Select 8'' High Excursion Woofer - 120W RMS 4ohm | 55-2421 (552421) | MCM Audio Select
With a sub amplifier that has built in bass boost facilities.
Search here on the models driver number and you will find the specifications.
An ideal sealed box for two of them will turn out silly small, due to the low Qts.
Ideally you'd use it in a still relatively small cabinet with a 10" ABR, but
if you want silly small sealed with amplifier boost, it is the way to go.
The sealed sub would be an about 12" external cube, including grilles.
rgds, sreten.
If you research it, you will find it really is a one-off driver,
very similar to a Tangband sub that is double the price.
FWIW of you want to build a small powerful subwoofer use two of these :
MCM Audio Select 8'' High Excursion Woofer - 120W RMS 4ohm | 55-2421 (552421) | MCM Audio Select
With a sub amplifier that has built in bass boost facilities.
Search here on the models driver number and you will find the specifications.
An ideal sealed box for two of them will turn out silly small, due to the low Qts.
Ideally you'd use it in a still relatively small cabinet with a 10" ABR, but
if you want silly small sealed with amplifier boost, it is the way to go.
The sealed sub would be an about 12" external cube, including grilles.
rgds, sreten.
If you research it, you will find it really is a one-off driver,
very similar to a Tangband sub that is double the price.
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