Julian, yes I have photos but they refuse to attach to my emails(may be too high res. or the wrong type of file.
Anyhow, the end result is that I have dismantled the prototype after discovering that the ''NOISE'' was NOT BEARING NOISE , but in actual fact noise from loose buzzing voice coils(only held in to the aluminium forks with a drop or two of super glue) and movement of the fork attached to the main bearing shaft (also glued on).
This is where the secret of success lies : the dual forks and voice coils need to be RIGID.....hell.........EVERYTHING NEEDS TO BE RIGID (as mentioned some where by Paul, the designer of the PLANOT) !!!!!!
😉 I will state with great confidence that what was heard before the noise trouble appeared, and that was for only a short period of testing, whas this :
THE SOUND PRODUCED WAS AMAZINGLY FAST, SCARINGLY REAL AND WEIRDLY SPATIAL - even with a piece of balsa triangle which was not an equal dimensined one as it was cut diagonally from a square rod(one face was larger than the other two).
So, the concept is worth pursuing if you have access to the machinery/personell or PLANOT decides to release this design in a kit form at a price that would be considered reasonable (whatever that may be?).
🙂
Anyhow, the end result is that I have dismantled the prototype after discovering that the ''NOISE'' was NOT BEARING NOISE , but in actual fact noise from loose buzzing voice coils(only held in to the aluminium forks with a drop or two of super glue) and movement of the fork attached to the main bearing shaft (also glued on).
This is where the secret of success lies : the dual forks and voice coils need to be RIGID.....hell.........EVERYTHING NEEDS TO BE RIGID (as mentioned some where by Paul, the designer of the PLANOT) !!!!!!
😉 I will state with great confidence that what was heard before the noise trouble appeared, and that was for only a short period of testing, whas this :
THE SOUND PRODUCED WAS AMAZINGLY FAST, SCARINGLY REAL AND WEIRDLY SPATIAL - even with a piece of balsa triangle which was not an equal dimensined one as it was cut diagonally from a square rod(one face was larger than the other two).
So, the concept is worth pursuing if you have access to the machinery/personell or PLANOT decides to release this design in a kit form at a price that would be considered reasonable (whatever that may be?).
🙂
It sounds tantalizing!
Could you use the motor/bearings from disk drives directly, without bothering with arm/voice coils? So you'd remove a motor from each of two disk drives, remove the platters, use one motor for the top of the triangular rod, unpowered, just for a bearing, and the second motor at the base, with the amplifier output connected to the motor terminals. Then, that motor will turn back and forth with the musical signal. In theory, anyway. You'd still need the positioning magnets on the rod and the base. Maybe there would be too much inertia, or the motors require too much current to start, or something?
Could you use the motor/bearings from disk drives directly, without bothering with arm/voice coils? So you'd remove a motor from each of two disk drives, remove the platters, use one motor for the top of the triangular rod, unpowered, just for a bearing, and the second motor at the base, with the amplifier output connected to the motor terminals. Then, that motor will turn back and forth with the musical signal. In theory, anyway. You'd still need the positioning magnets on the rod and the base. Maybe there would be too much inertia, or the motors require too much current to start, or something?
Ziggy,
I've been following this since my input a few pages back. Thinking technically, I wondered if the bearings could not be replaced by a simple flexure. This should allow torsional motion, but restict vertical movement. It would, in addition, be capable of providing a centering force for the assembly.
In it's simplest embodiment, a torsion wire suspension could work - rather like the old fasioned moving coil galvanometer from my university physics lab.
Ed
P.S. paint a little varnish on the voice coils.
I've been following this since my input a few pages back. Thinking technically, I wondered if the bearings could not be replaced by a simple flexure. This should allow torsional motion, but restict vertical movement. It would, in addition, be capable of providing a centering force for the assembly.
In it's simplest embodiment, a torsion wire suspension could work - rather like the old fasioned moving coil galvanometer from my university physics lab.
Ed
P.S. paint a little varnish on the voice coils.
Thanks for the input guys.
jjbun :unfortunately, connecting the motor of a hard disk doesn't produce much in the way of vibration - current required is way too much.I tried this already
Ed, don't fully understand the principle you describe but from what I gather, it's an interesting concept.
The main point however, is that whatever the method of rotation or pivot, the structure must be rigid without any flexure of any of it's parts. This I have discovered quickly as being the golden rule.
Even the bearings are not that critical, but, the way the voice coils and rod are attached to it is - very much so.
I have also found that energy(sound) can easily be wasted away with poor alignment or coupling of the various bits and pieces.
As I fiddled with this set up I could make the music louder or softer with better bass or no bass etc. In the end, everything just fell apart and started buzzing.
It really needs to be rebuilt with real parts - not salvaged ones.
jjbun :unfortunately, connecting the motor of a hard disk doesn't produce much in the way of vibration - current required is way too much.I tried this already
Ed, don't fully understand the principle you describe but from what I gather, it's an interesting concept.
The main point however, is that whatever the method of rotation or pivot, the structure must be rigid without any flexure of any of it's parts. This I have discovered quickly as being the golden rule.
Even the bearings are not that critical, but, the way the voice coils and rod are attached to it is - very much so.
I have also found that energy(sound) can easily be wasted away with poor alignment or coupling of the various bits and pieces.
As I fiddled with this set up I could make the music louder or softer with better bass or no bass etc. In the end, everything just fell apart and started buzzing.
It really needs to be rebuilt with real parts - not salvaged ones.
As I work for a technical education institution, and we have a mechanical engineering section, I might seek their help on this one.
Perhaps there is something out there that can solve the problems discussed😀
Perhaps there is something out there that can solve the problems discussed😀
Ziggy,
Here you go :http://farside.ph.utexas.edu/teaching/301/lectures/node139.html
That is the basics of torsion suspension physics. You'd have a wire at the top and bottom of the moving assembly that responds in an elastic way to twisting. However, I note your comments about rigid constraint. This could be a problem with a simple wire, as it would be hard ensure lateral motion was completely prevented.
Ed
Here you go :http://farside.ph.utexas.edu/teaching/301/lectures/node139.html
That is the basics of torsion suspension physics. You'd have a wire at the top and bottom of the moving assembly that responds in an elastic way to twisting. However, I note your comments about rigid constraint. This could be a problem with a simple wire, as it would be hard ensure lateral motion was completely prevented.
Ed
Hi Ziggy.
I made a little prototype myself this evening ... and it worked. Actually, how could it fail to work - the principle is foolproof, it's just a question of how well it works😀
I took an old Micropolis hard disk's actuator arm and voice coils, together with the magnets, and mounted them on a board. (For some reason this disk had two voice coils, and two magnet pairs, with the voice coils wired in parallel.) The voice coil resistance was about 5 Ohms.
Then I cut a 15" length of 1/2" square balsa wood and glued it to the top of the arm, central to the bearings. Here's a photo:
I attached a pair of wires to the voice coils, and powered them up with the amp. The music played surprisingly loud, and brightly. There was a bit of vibration of the board, and I suspect the balsa wood was fluttering a little at the top, since it was unattached there.
The thing works fairly well, and for a cobbled together experiment it's great! I took a little movie which you can see and listen to here:
http://www.youtube.com/watch?v=ZeGtdKoxk20
I made a little prototype myself this evening ... and it worked. Actually, how could it fail to work - the principle is foolproof, it's just a question of how well it works😀
I took an old Micropolis hard disk's actuator arm and voice coils, together with the magnets, and mounted them on a board. (For some reason this disk had two voice coils, and two magnet pairs, with the voice coils wired in parallel.) The voice coil resistance was about 5 Ohms.
Then I cut a 15" length of 1/2" square balsa wood and glued it to the top of the arm, central to the bearings. Here's a photo:
An externally hosted image should be here but it was not working when we last tested it.
I attached a pair of wires to the voice coils, and powered them up with the amp. The music played surprisingly loud, and brightly. There was a bit of vibration of the board, and I suspect the balsa wood was fluttering a little at the top, since it was unattached there.
The thing works fairly well, and for a cobbled together experiment it's great! I took a little movie which you can see and listen to here:
http://www.youtube.com/watch?v=ZeGtdKoxk20
I suspect many modes (pun intended) are at work in this concept. This makes it at once intriguing and hard to assess & develop.
Thanks for posting jbunn, interesting video, too.
Ed Holland said:
Probably the trick is to eliminate the longitudinal and transverse vibrations of the rod so that only the rotational motion remains. Fixing the upper end of the rod in a bearing is probably very important, and that's what I will try next.
Well done Julian !!😉
My original and first attempt was similar, but your dual coil hard drive assemble is far superior than what I had to play with.
15'' long balsa will exhibit less problems than a 3 foot one - heaps of extra vibrations and yes IT MUST BE ANCHORED AT THE TOP TO ANOTHER BEARING and some way of holding this bearing in line with the rest of the assembly (I never got around to doing this due to the other problems I was faced with).There will of course be less bass output due to total surface area.
Keep up with your experiments because I haven't given up and will continue to try various alternatives.
😎
This time around I will be using a modified(ends turned smooth on a lathe)threaded brass rod with a short thread left in the middle so that brass nuts can be used to secure a larger hand made dual fork and voice coil assembly.
This rod will be held at the top and bottom with low noise/low friction bearings considerably better than the hard drive types used in my past efforts.
As I have previously mentioned, the magnets will be top and bottom 1.5''neo. disk magnets - lots of field strength here!
Instead of Balsa, I will try a 6 foot rod cut from polystyrene and strengthened with a special resin that is designed specifiaclly for polystyrene. I am hoping that this will sound better than balsa which has a distictive ''wooden ring'' to it. Maybe that's because it wasn't correctly secured at the top?. Who knows?
Anyhow, let's all work together on this and see if there is any merit to this planar pivoting contraption😀
My original and first attempt was similar, but your dual coil hard drive assemble is far superior than what I had to play with.
15'' long balsa will exhibit less problems than a 3 foot one - heaps of extra vibrations and yes IT MUST BE ANCHORED AT THE TOP TO ANOTHER BEARING and some way of holding this bearing in line with the rest of the assembly (I never got around to doing this due to the other problems I was faced with).There will of course be less bass output due to total surface area.
Keep up with your experiments because I haven't given up and will continue to try various alternatives.
😎
This time around I will be using a modified(ends turned smooth on a lathe)threaded brass rod with a short thread left in the middle so that brass nuts can be used to secure a larger hand made dual fork and voice coil assembly.
This rod will be held at the top and bottom with low noise/low friction bearings considerably better than the hard drive types used in my past efforts.
As I have previously mentioned, the magnets will be top and bottom 1.5''neo. disk magnets - lots of field strength here!
Instead of Balsa, I will try a 6 foot rod cut from polystyrene and strengthened with a special resin that is designed specifiaclly for polystyrene. I am hoping that this will sound better than balsa which has a distictive ''wooden ring'' to it. Maybe that's because it wasn't correctly secured at the top?. Who knows?
Anyhow, let's all work together on this and see if there is any merit to this planar pivoting contraption😀
Oh, just another point of interest for all concerned : The base that Julian used to mount his prototype will act as a ''pickup'' or vibrating panel that also produces sound ..... NXT style!!!...if you know what I mean?
If Julian removes the board and holds the magnet/rod assembly using only his hands, the volume of sound will diminish considerably🙁
On the PLANOT web site gallery, you will see(the photo in the anechoic chamber) that there are weights holding the thing down, or, stopping unwanted vibrations??
On the home page, the P4, latest prototype photo, the designer has obviously used a number of tricks to supress vibrations - large nylon base and possibly thin spikes??in various places. Note also that he now has TWO homing magnets instead of one. Hmmmmmm?????????............INERTIA ?????????LINEARITY?????
If Julian removes the board and holds the magnet/rod assembly using only his hands, the volume of sound will diminish considerably🙁
On the PLANOT web site gallery, you will see(the photo in the anechoic chamber) that there are weights holding the thing down, or, stopping unwanted vibrations??
On the home page, the P4, latest prototype photo, the designer has obviously used a number of tricks to supress vibrations - large nylon base and possibly thin spikes??in various places. Note also that he now has TWO homing magnets instead of one. Hmmmmmm?????????............INERTIA ?????????LINEARITY?????
I just started reading this thread, but had investigated the planot driver a while back, I found it interesting. So I thought I throw a few ideas out.......
1. The planot in its present form will not be efficient or linear, and the use of homing magnets will reduce efficiency even further.
2. The transducer medium has to have close to zero resonance, the hole idea behind the speaker is to produce sound from the direct mechanical movement of air.
3. Resonance is its enemy any vibration produced by the motor structure will effect the transducer, housing, just about everything.
So I will throw out a couple ideas, the motor structure rotational point magnet motors i.e. hard drives wont work period. why not change to piston type motor assemblies, just like a good old voice coil to actuate the transducer one voice coil to push and one to pull connected on opposite side of the transducer??? now there will be no need of homing magnets and the connected loss of sensitivity.
Piston type motors will be easier to isolate, can easily be designed for long throws and in a push pull setup be linear.
Fluid damped bearings for isolation and a bunch of other stuff.
If anybody is interested let me know, I would really like some input to hammer out problems before I build a version.
1. The planot in its present form will not be efficient or linear, and the use of homing magnets will reduce efficiency even further.
2. The transducer medium has to have close to zero resonance, the hole idea behind the speaker is to produce sound from the direct mechanical movement of air.
3. Resonance is its enemy any vibration produced by the motor structure will effect the transducer, housing, just about everything.
So I will throw out a couple ideas, the motor structure rotational point magnet motors i.e. hard drives wont work period. why not change to piston type motor assemblies, just like a good old voice coil to actuate the transducer one voice coil to push and one to pull connected on opposite side of the transducer??? now there will be no need of homing magnets and the connected loss of sensitivity.
Piston type motors will be easier to isolate, can easily be designed for long throws and in a push pull setup be linear.
Fluid damped bearings for isolation and a bunch of other stuff.
If anybody is interested let me know, I would really like some input to hammer out problems before I build a version.
Yes, Ziggy ... the small oval board acts as a sounder, and I can eliminate it doing so by pressing it against the table. I intend to screw it down to a large heavy wooden block, which the vertical gantry for the upper bearing will also be attached to.
The homing magnets are puzzling to me: why are they needed? The coils don't tend to move much at all, and come to rest in the centre of the magnets with zero current anyway.
I'm not sure how a piston type motor arrangement, as tiltedhalo suggests, would be set up.
The homing magnets are puzzling to me: why are they needed? The coils don't tend to move much at all, and come to rest in the centre of the magnets with zero current anyway.
I'm not sure how a piston type motor arrangement, as tiltedhalo suggests, would be set up.
Ziggy said:Well done Julian !!😉
My original and first attempt was similar, but your dual coil hard drive assemble is far superior than what I had to play with.
15'' long balsa will exhibit less problems than a 3 foot one - heaps of extra vibrations and yes IT MUST BE ANCHORED AT THE TOP TO ANOTHER BEARING and some way of holding this bearing in line with the rest of the assembly (I never got around to doing this due to the other problems I was faced with).There will of course be less bass output due to total surface area.
Keep up with your experiments because I haven't given up and will continue to try various alternatives.
😎
This time around I will be using a modified(ends turned smooth on a lathe)threaded brass rod with a short thread left in the middle so that brass nuts can be used to secure a larger hand made dual fork and voice coil assembly.
This rod will be held at the top and bottom with low noise/low friction bearings considerably better than the hard drive types used in my past efforts.
As I have previously mentioned, the magnets will be top and bottom 1.5''neo. disk magnets - lots of field strength here!
Instead of Balsa, I will try a 6 foot rod cut from polystyrene and strengthened with a special resin that is designed specifiaclly for polystyrene. I am hoping that this will sound better than balsa which has a distictive ''wooden ring'' to it. Maybe that's because it wasn't correctly secured at the top?. Who knows?
Anyhow, let's all work together on this and see if there is any merit to this planar pivoting contraption😀
Maybe it was suggested already somewhere in the thread, but why not place matching motors at BOTH top and bottom. 'Would greatly reduce any torsional issues. Individual motors could be smaller. Eliminate need for any bearing(s) - simply suspend on a long string that doesn't mind twisting a little. String mass/length/tension can be chosen to damp rod vibration and place system resonance below operating range. Given low mass and reasonable motors, the rod would be practically floating and (in its direction of motion) practically frictionless. All that's left to deal with is mass & resonances. with double motors, more mass is tolerable, and can be in the form of damping compound or use of less resonant materials
Thoughts?
-- TubaMark
You can extend the idea even further.
Use a magnet assembly from top to bottom and actuate the diagraphm on its entire length. With small powerfull magnets you can probably place it inside the rod/diagraphm.
There is no need for homage magnets, when the loudspeaker is connected to the amp the diagrapm centers itself.
Omit traditional bearings and use some kind of torsion bar.
JB
Use a magnet assembly from top to bottom and actuate the diagraphm on its entire length. With small powerfull magnets you can probably place it inside the rod/diagraphm.
There is no need for homage magnets, when the loudspeaker is connected to the amp the diagrapm centers itself.
Omit traditional bearings and use some kind of torsion bar.
JB
thinkbad said:
Correct me if I am wrong, but shouldn't he diaphragm/rod assembly ideally be massless and infinitely stiff?
So it seems to me that some sort of very light, stiff metal would be best? If the metal was also magnetic, then you could make vanes at the base and tip of the rod that lie between voice coils. That would have the advantage of avoiding voice coil wires having to be attached to the moving part of the apparatus.
jjbunn, you are absolutely correct !
Imagine the magnet inside the "coil", just like an ordinary loudspeaker motor. Only the diagraphm/tube moves.
JB
Imagine the magnet inside the "coil", just like an ordinary loudspeaker motor. Only the diagraphm/tube moves.
JB
Planot.....
Some of you critics will be eating your words soon.
John, I will call you tomorrow in reference to your email.
God bless,
Robert
Your Southern Friend
Some of you critics will be eating your words soon.
John, I will call you tomorrow in reference to your email.
God bless,
Robert
Your Southern Friend
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