As someone else said, what you have devised must be exceedingly better than the "prior art", or else you don't have a driver that will earn you some money. Your mechanism for producing suspension by means of a magnetic field is much more costly than a spider and surround, isn't it? That means that there must be some great benefit from magnetic suspension compared to the "prior art".
Utility patents these days are for the major corporations or else (already) very wealthy individuals. Unless you are either one of those, patents are a waste of time. Just ask Earl Geddes.
Regards,
cT
Utility patents these days are for the major corporations or else (already) very wealthy individuals. Unless you are either one of those, patents are a waste of time. Just ask Earl Geddes.
Regards,
cT
I have to say I don't like the way the comments in this thread have gone so far. This person spent years making something work and they didn't ask whether anyone thinks it was a good idea or not. The performance almost certainly can be improved whether it is a good idea or not, and nobody has seen any very meaningful measurements of how it is performing right now. This is a DIY forum. Granted, the first post sort of invites sceptical criticism, and granted, most people around here (including me) don't like when someone says how great something is, doesn't say how it works, and doesn't post good measurements, but still, this is a DIY forum.
You should all be helping this person with performing meaningful tests with whatever is available to them (we know very little about that, as far as I can tell). Or, if you don't want to help in any way including performance evaluation because the project is not purely open to the public, that's fair, but then maybe leave it alone? As long as Jef Nuyts is interested in providing good test data, I think the testing should be supported wholeheartedly despite any secrecy about the engineering of the actual transducer, and I think the testing should be the primary focus of discussion.
You should all be helping this person with performing meaningful tests with whatever is available to them (we know very little about that, as far as I can tell). Or, if you don't want to help in any way including performance evaluation because the project is not purely open to the public, that's fair, but then maybe leave it alone? As long as Jef Nuyts is interested in providing good test data, I think the testing should be supported wholeheartedly despite any secrecy about the engineering of the actual transducer, and I think the testing should be the primary focus of discussion.
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Hi,
@cT equals piD and others
It did has some advantages over normal suspension like adjustable, full lineair => you can drive the speaker to its limits and there is no audible distortion, this is very importand if you go 2-way as the driver has to do high and lows. I did test the speaker yesterday to drive as hard as it can be Xmax +/- 10-12mm and it keeps playing very clear. But for now I have to say dumptruck has a point over the whole line so maybe it is better to take another path and finalise my project, go to audio exhibitions so people can hear it. This thread was to see if I had to go further or stop with the project but on this moment it is almost ready so stopping is not a option ;-) Maybe on one day you see this speakers on some website I can't tell for now. For people who is interested for the rest of this project you can always send a private massage. I will love to answer. If it is a fail a will post how it works.
Thanks for the reply's and all the best!
Regards,
Jef
@cT equals piD and others
It did has some advantages over normal suspension like adjustable, full lineair => you can drive the speaker to its limits and there is no audible distortion, this is very importand if you go 2-way as the driver has to do high and lows. I did test the speaker yesterday to drive as hard as it can be Xmax +/- 10-12mm and it keeps playing very clear. But for now I have to say dumptruck has a point over the whole line so maybe it is better to take another path and finalise my project, go to audio exhibitions so people can hear it. This thread was to see if I had to go further or stop with the project but on this moment it is almost ready so stopping is not a option ;-) Maybe on one day you see this speakers on some website I can't tell for now. For people who is interested for the rest of this project you can always send a private massage. I will love to answer. If it is a fail a will post how it works.
Thanks for the reply's and all the best!
Regards,
Jef
Partner with a loudspeaker company
Hi Jef,
One you get a pair of working drivers that are fully developed and ready for production ( DFM - Designed For Manufacture is a key part of R&D) you could partner with a high end loudspeaker manufacturer.
A medium sized company will be able put in the resources to get the first 50pairs or so built and then release a flagship loudspeaker with your driver.
If that goes well there would be significant savings when building 1,000 drivers and you can widen the market with a "trickle down technology" version in a year or so.
Some key technical points:
(1) There should be a significant increase in sensitivity when you replace a high friction spider / suspension/ surround with a zero friction magnetic suspension. Please advise if you have found this to be the case?
What is the Mms and Bl? The ratio is key, its ok to have a low or medium Mms as long as the Bl is high enough to give something around 2:1 ie an Mms of
20g with Bl around 10.
(2) The single biggest failing in conventional "push pull" drivers (they are never pistonic!) is the slow settling time (clearly seen in the horrendous waterfall plot graphs), if you can show a really clean waterfall plot that will get the attention of any good loudspeaker designer!
I have attached a description of conventional push pull mass on a spring driver behaviour.
Hope this helps and all the very best with your great project, you have done a great job so far and all you need now is a bit of luck in finding a good business partner!
PS Trust no-one.....Always use NDA's ( Non disclosure Agreements) ie get them to sign one first, before you disclose any confidential / technical information.
I can send you a good NDA if you don't already have one, just PM me.
Cheers
Derek.
Hi Jef,
One you get a pair of working drivers that are fully developed and ready for production ( DFM - Designed For Manufacture is a key part of R&D) you could partner with a high end loudspeaker manufacturer.
A medium sized company will be able put in the resources to get the first 50pairs or so built and then release a flagship loudspeaker with your driver.
If that goes well there would be significant savings when building 1,000 drivers and you can widen the market with a "trickle down technology" version in a year or so.
Some key technical points:
(1) There should be a significant increase in sensitivity when you replace a high friction spider / suspension/ surround with a zero friction magnetic suspension. Please advise if you have found this to be the case?
What is the Mms and Bl? The ratio is key, its ok to have a low or medium Mms as long as the Bl is high enough to give something around 2:1 ie an Mms of
20g with Bl around 10.
(2) The single biggest failing in conventional "push pull" drivers (they are never pistonic!) is the slow settling time (clearly seen in the horrendous waterfall plot graphs), if you can show a really clean waterfall plot that will get the attention of any good loudspeaker designer!
I have attached a description of conventional push pull mass on a spring driver behaviour.
Hope this helps and all the very best with your great project, you have done a great job so far and all you need now is a bit of luck in finding a good business partner!
PS Trust no-one.....Always use NDA's ( Non disclosure Agreements) ie get them to sign one first, before you disclose any confidential / technical information.
I can send you a good NDA if you don't already have one, just PM me.
Cheers
Derek.
Hi Derek,
Thanks for the info this is the kind I need.
I have a waterfall of an older version this give an idea. (not high quality measurement) and the freq. response is not optimal but you can see the changes in time.
BL is droped from 9 to 7NA Mms is 18gr with the latest version. I have ordered some prof. paper cones so I want bring back Mms around 14-16gr.
regards,
Thanks for the info this is the kind I need.
I have a waterfall of an older version this give an idea. (not high quality measurement) and the freq. response is not optimal but you can see the changes in time.
BL is droped from 9 to 7NA Mms is 18gr with the latest version. I have ordered some prof. paper cones so I want bring back Mms around 14-16gr.
regards,
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Looks interesting
Hi Jef,
Your graph looks very interesting, despite the scale issues, its very even and smooth from low to high....That's unique and shows you have something good going on!
Your target of 14g Mms with a Bl of 7 sounds perfect...If your driver is around 8 inch diameter, Sd should be around 220 cm2 or maybe a bit more?
You will have better low end performance than my 4.5 inch ( Sd of 70) silk surround BMR, it has a Mms of 6.03g and a Bl of 4.82 giving a very fast ratio of 1.25 :1. If you can get the top end to extend out to around 15 KHz you will have a great driver on your hands.
Please explain the time scale on your graph, I see 700 ms at the end, but the important settling time is all in the first 1 or 2 ms seconds ...
I can email you a waterfall plot ( the file is too big too big to post here) of my silk surround BMR which is totally clean after 1 milli second...
All the best
Derek.
Hi Jef,
Your graph looks very interesting, despite the scale issues, its very even and smooth from low to high....That's unique and shows you have something good going on!
Your target of 14g Mms with a Bl of 7 sounds perfect...If your driver is around 8 inch diameter, Sd should be around 220 cm2 or maybe a bit more?
You will have better low end performance than my 4.5 inch ( Sd of 70) silk surround BMR, it has a Mms of 6.03g and a Bl of 4.82 giving a very fast ratio of 1.25 :1. If you can get the top end to extend out to around 15 KHz you will have a great driver on your hands.
Please explain the time scale on your graph, I see 700 ms at the end, but the important settling time is all in the first 1 or 2 ms seconds ...
I can email you a waterfall plot ( the file is too big too big to post here) of my silk surround BMR which is totally clean after 1 milli second...
All the best
Derek.
Hi,
Did yesterday a test comparing to the gamut L5. Just mono because the second speaker is not ready yet.
There was a "audiophile" customer at my brother's store (a man with big bucks and 30 years of experience not as a developer but as a buyer). He is willing to buy this speaker as soon as possible ;-) I must say the sound was more open and rich as the gamut and I think this must say something. The low's are so low and clean without sacrificing the openness. The next step is to evaluate the soundstage. If this is as good as we hope for, this speaker definitely goes in production.
what this guy say's:
the sound is incredibly alive
great dispertion
good dynamics
Oke I know this won't say anything for you guy's but in the future i hope it will.
The guy and also my brother say the same, if someone was saying this to me I also wouldn't beleive it and won't pay attention to it.
If soundstage is oke. For people of holland, germany... the next step is to demonstrate this speaker in Holland. Around next year, you won't be dissapointed I promise...
Regards,
Did yesterday a test comparing to the gamut L5. Just mono because the second speaker is not ready yet.
There was a "audiophile" customer at my brother's store (a man with big bucks and 30 years of experience not as a developer but as a buyer). He is willing to buy this speaker as soon as possible ;-) I must say the sound was more open and rich as the gamut and I think this must say something. The low's are so low and clean without sacrificing the openness. The next step is to evaluate the soundstage. If this is as good as we hope for, this speaker definitely goes in production.
what this guy say's:
the sound is incredibly alive
great dispertion
good dynamics
Oke I know this won't say anything for you guy's but in the future i hope it will.
The guy and also my brother say the same, if someone was saying this to me I also wouldn't beleive it and won't pay attention to it.
If soundstage is oke. For people of holland, germany... the next step is to demonstrate this speaker in Holland. Around next year, you won't be dissapointed I promise...
Regards,
Jef can you explain the main differences in a nut shell, from this driver and B&W mid yellow cone.
Sorry for taking your previous post out of context and posting a different picture in your thread of Kevlar B&W’s cone, hope you don't mind.
Oké no problem at all my man!
I try to explain:
The B&W kevlar cone has a very small excursion only usable for mid tones not for bass.
You can see the b&W driver use a small spider (less resonance as a large spider) but also small excursion. If you use a small spider and will use it for large excursions it is not lineair because of the changing angle to the voicecoil.
The B&W also don't use a surround but the cone is direct attached to the basket. My driver is attached to anything for now. I don't know if I keep this, also going to try with a very soft surround because this is easier to build (only if the sound stay's the same).
My driver is build for two way = > less problems with phase shifts between two drivers. This is why I spend alot of time for the best compromise between low and high freq. response. For me a good driver must have sufficient low freq. output (40Hz) with good high freq. capabilities till 4-5Khz.
Also if you use one driver for very low freq. and high the excursion can be large but the sound must be kept clear => in my case of the very lineair excursion till 8mm results in a super clear (read not compressed) sound at high volumes. The cone can travel way more till 15mm but not like a normal driver even in this case it is not compressed. Why? the suspension in this case is less as it should be but not more so it stays clear. If you go further the cone will pops out. tried that
put back in and no problem at all in a nutshell:
I think the sound is that good because of the large displacement without distortion and the use of 2-way not three or more the prevent problems with phase shifts between two drivers.
questions? please ask.
Would your design work at subwoofer frequencies as well? The fact that you can get such large excursions cleanly immediately makes me think of it's use as a subwoofer, especially where you said "If you go further the cone will pops out" - I'm sure lots of folks will be happy that over-excursion doesn't destroy your speaker completly
Would your design work at subwoofer frequencies as well? The fact that you can get such large excursions cleanly immediately makes me think of it's use as a subwoofer, especially where you said "If you go further the cone will pops out" - I'm sure lots of folks will be happy that over-excursion doesn't destroy your speaker completly
yes it would because I can change the design for larger excursions.
I didn't done that but in theory Xmax p-p 16mm would be possible.
there is some increase in weight but for sub. this is not a problem.
when it pops out it is not just as simple as put it back in
The ferrofluid must be take out and put it back in after the cone is placed. (but the driver isn't distroyed)
=> with this prototype there is no stop on the end of the excursion but the final version will have it so popping out is no problem.
cheers,
Very simplistic not considering the back plate....where you said "If you go further the cone will pops out" - I'm sure lots of folks will be happy that over-excursion doesn't destroy your speaker completly
Just made a FR-plot in normal room circumstances. So there are some peaks of the room reflections but I think not bad and pretty flat.
70liter basreflex case tuned at 50Hz
There is only used one filter: -7db 2oct at 3000hz (baffle step compensation).
and a hp-filter for the tweeter. No LP for the midbas. No gain for the low's.
Question, the FR-plot is flat but the sound is not warm yet there is enough bass.
I do think if I change the kevlar cone with paper the problem is solved? Suggestions?
Thanks
70liter basreflex case tuned at 50Hz
There is only used one filter: -7db 2oct at 3000hz (baffle step compensation).
and a hp-filter for the tweeter. No LP for the midbas. No gain for the low's.
Question, the FR-plot is flat but the sound is not warm yet there is enough bass.
I do think if I change the kevlar cone with paper the problem is solved? Suggestions?
Thanks
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If you want to show your driver, please disconnect the tweeter, post a nearfield measurement ~1cm from the cone, and time-windowed measurements without reflections from 0.5-1.5m or so at a few angles. The graph above doesn't show much of anything, really. Also, a 30-40dB scale would be more appropriate than 100dB.
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Oke I did a quick measurement (near field 1.5cm) of the driver. This is not in a IEC baffle or open baffle so I think there are some backwave distortions. Also do I have problems in my room with the 100Hz drop. (all my speakers do have some trouble about this here). The best result i get was in the middle of the room but it is still there.
If I got the time I will do some measurements outside in a open baffle (if this is a good idea?). But I hope you do have some idea from this graph.
Please advise.
regards,
If I got the time I will do some measurements outside in a open baffle (if this is a good idea?). But I hope you do have some idea from this graph.
Please advise.
regards,
Attachments
For mid-high frequencies, use a program with time-windowed impulse measurements and you won't need to go outside. REW, HolmImpulse, ARTA, etc.
For low frequencies, you should be able to get nearly 100% clean low frequency response from nearfield, but I'm not familiar with trueRTA so in the image above, I'm not sure whether you're seeing something that's really happening with the cabinet+driver, or if something else happened.
Maybe you should try measuring a conventional speaker to make sure you are getting normal measurement results first?
If that's the bass reflex cabinet, it should show a dip at the tuning frequency, which you said was 50Hz, but it looks like above maybe it is actually tuned to 36Hz and the rise below 30 Hz is just noise or the microphone, maybe. Here's a typical bass reflex tuned to 50Hz and measured nearfield 1cm:
For low frequencies, you should be able to get nearly 100% clean low frequency response from nearfield, but I'm not familiar with trueRTA so in the image above, I'm not sure whether you're seeing something that's really happening with the cabinet+driver, or if something else happened.
Maybe you should try measuring a conventional speaker to make sure you are getting normal measurement results first?
If that's the bass reflex cabinet, it should show a dip at the tuning frequency, which you said was 50Hz, but it looks like above maybe it is actually tuned to 36Hz and the rise below 30 Hz is just noise or the microphone, maybe. Here's a typical bass reflex tuned to 50Hz and measured nearfield 1cm:
Attachments
Some polar plots would be nice to see. I wonder what the effect is of the inverted cone. If interested, pm me about taking some detailed measurements, I have an automated setup for measurements and report generation.
Years ago I'm sure i saw a patent for a driver like this. However, if i recall correctly it used twin voice coils, axially displaced along the former, these were driven differentially, and the DC 'suspension' was provided using a DC bias current superimposed onto the music signal input, much like electrostatics.
Interesting project.
Interesting project.
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