Re: Power compression
What makes you think our voice coil wire is inferior? If there is something better I want to see it and will incorporate it into the design if it is actually better.
Why would the thickness matter in this case? The voice coil is basically directly wound onto the aluminum with only a thin layer of perforated Nomex sandwiched in between. I have not done the tests I will admit but I would imagine the voice coil winding temperature is pretty close to the temp of the aluminum former in my design, so much so I had a layer of Kapton installed above the aluminum for the cone and spider junction.
IMHO - you sure know a lot about drivers you have never tested nor seen the design details of.
mige0 said:
What makes you think our voice coil wire is inferior? If there is something better I want to see it and will incorporate it into the design if it is actually better.
Sure the aluminium part of your VC helps to enlarge the radiating area of the coil itself – but the aluminium material usually is too thin to allow for massive heat transport (I leave that quick calculation to someone else)
Why would the thickness matter in this case? The voice coil is basically directly wound onto the aluminum with only a thin layer of perforated Nomex sandwiched in between. I have not done the tests I will admit but I would imagine the voice coil winding temperature is pretty close to the temp of the aluminum former in my design, so much so I had a layer of Kapton installed above the aluminum for the cone and spider junction.
IMHO - you sure know a lot about drivers you have never tested nor seen the design details of.
Re: Re: Re: Re: Re: Re: Interesting Paper from 18Sound
If the lateral effect was small, and it should be perfectly balanced, although not stable, I could see where the axial centering effect would be a positive thing.
Have you actually tried this? A few % nickel doesn't seem like it would be a big magnetic attractor, but there is a large field. The question would be stability because a slight off center causes a larger force.
John_E_Janowitz said:
If the lateral effect was small, and it should be perfectly balanced, although not stable, I could see where the axial centering effect would be a positive thing.
Have you actually tried this? A few % nickel doesn't seem like it would be a big magnetic attractor, but there is a large field. The question would be stability because a slight off center causes a larger force.
Re: Re: Power compression
Don't take me wrong in this, Nick.
Your VC wire is as good as any other out there. Its either copper or aluminium (probably with a grain of silver) with its well known properties – its just that the materials currently available are inferior for that application - and strange enough – considering the efforts made to reduce 0,00000x% distortion at other aspects - not that much development on that - the last few decades (actually on from the very beginning of driver building), as far as I can see.
You got me. Never built a dynamic driver – just disassembled some and fooled around with electrostats.
Beside that the underlaying technical context is common knowledge and nothing subject to personal taste.
The thickness of the aluminium in the VC matters because you want it to transmit heat.
The "hermal resistance" of a certain part depends of the
- material property
- the length of your part
- the cross section (?) of your part
nothing magic in here...
Greetings
Michael
nickmckinney said:
Don't take me wrong in this, Nick.
Your VC wire is as good as any other out there. Its either copper or aluminium (probably with a grain of silver) with its well known properties – its just that the materials currently available are inferior for that application - and strange enough – considering the efforts made to reduce 0,00000x% distortion at other aspects - not that much development on that - the last few decades (actually on from the very beginning of driver building), as far as I can see.
nickmckinney said:
You got me. Never built a dynamic driver – just disassembled some and fooled around with electrostats.
Beside that the underlaying technical context is common knowledge and nothing subject to personal taste.
The thickness of the aluminium in the VC matters because you want it to transmit heat.
The "hermal resistance" of a certain part depends of the
- material property
- the length of your part
- the cross section (?) of your part
nothing magic in here...
Greetings
Michael
Re: Re: Re: Power compression
You keep saying the current voice coil materials are inferior, well what is better already and how is it better? Teach me something new and if it can be incorporated in the design it will be done pretty quickly.
BTW - we put a LOT of work and money into the design of the current TD/Apollo voice coils and learned quite a bit along the way with them. For example we don't have the solder problems of edgewound to the flex leads, we are able to mechanically crimp with our flatwire and get the same compact winding space as edgewound (we then seal the crimp with silver solder). There is a lot of science in these.
mige0 said:
You keep saying the current voice coil materials are inferior, well what is better already and how is it better? Teach me something new and if it can be incorporated in the design it will be done pretty quickly.
BTW - we put a LOT of work and money into the design of the current TD/Apollo voice coils and learned quite a bit along the way with them. For example we don't have the solder problems of edgewound to the flex leads, we are able to mechanically crimp with our flatwire and get the same compact winding space as edgewound (we then seal the crimp with silver solder). There is a lot of science in these.
Re: Re: Re: Re: Power compression
If it doesn't exist yet, there is no need to talk about it and say the current offerings are inferior. Everything in life would be inferior in this context.
IMHO the material the VC wire is made from is not the problem with the magnetic gap distortion, its the fact that turns of any wire around a steel pole makes an electromagnet once you deliver the current. This electromagnet goes back and forth in phase and out of phase of the fixed magnet be it Alnico, ceramic, neo, etc. Of these ceramic is the most susceptible to its effects which is why we add electrically conductive material as close to the voice coil as possible.
Here is a website from Roger Russell describing the McIntosh patent of aluminum rings next to the coil. I have had the fortune of sipping lemonade at his house and he was the first to measure the frequency response of a Lambda/AE TD driver:
http://www.roger-russell.com/xr250.htm
Peter M. said:
If it doesn't exist yet, there is no need to talk about it and say the current offerings are inferior. Everything in life would be inferior in this context.
IMHO the material the VC wire is made from is not the problem with the magnetic gap distortion, its the fact that turns of any wire around a steel pole makes an electromagnet once you deliver the current. This electromagnet goes back and forth in phase and out of phase of the fixed magnet be it Alnico, ceramic, neo, etc. Of these ceramic is the most susceptible to its effects which is why we add electrically conductive material as close to the voice coil as possible.
Here is a website from Roger Russell describing the McIntosh patent of aluminum rings next to the coil. I have had the fortune of sipping lemonade at his house and he was the first to measure the frequency response of a Lambda/AE TD driver:
http://www.roger-russell.com/xr250.htm
Re: Re: Re: Re: Re: Re: Re: Interesting Paper from 18Sound
Hi Earl,
If it was possible to get these lateral effects perfectly balanced, it would be good. The problem is that it is not. Try to take a ring magnet and center a piece of steel directly in the middle. It just really isn't possible. Even the slightest movement from center and the piece of steel will be moved all the way to the side and stuck to the magnet.
I agree that at first glance the few % doesn't seem like a big attractor, but in reality the effects are pretty high. I have talked with several engineers from the larger pro audio companies over the past few years. The pro audio realm is really concerned with making bullet proof drivers. The combination of the ceramic coated wire, ceramic adhesives, and a high temperature former could be great in terms of not being able to burn up a driver. The current failure is in the insulation of the wire, or the adhesives. This mentioned combination would literally push the limits from around 600F with current adhesives/insulation to upwards of 1000F. You'd essentially have a coil where the DCR would rise so much you couldn't deliver any more power and not be able to burn up the coil.
Several of these companies have tried it and found it not at all suited for the reasons i mention. Others simply looked at the addition of any nickel and it's magnetic properties. I'm sure it could be done, but the issue would be the drawbacks. If you FEA it statically with say the 27% nickel clad copper wire in the gap, you can easily notice lots of stuff happening in the gap at different points of the travel. I don't have the ability to FEA it dynamically and see the effects that the moving coil has on the flux field, but I would imagine the effect is far from positive.
John
gedlee said:
Hi Earl,
If it was possible to get these lateral effects perfectly balanced, it would be good. The problem is that it is not. Try to take a ring magnet and center a piece of steel directly in the middle. It just really isn't possible. Even the slightest movement from center and the piece of steel will be moved all the way to the side and stuck to the magnet.
I agree that at first glance the few % doesn't seem like a big attractor, but in reality the effects are pretty high. I have talked with several engineers from the larger pro audio companies over the past few years. The pro audio realm is really concerned with making bullet proof drivers. The combination of the ceramic coated wire, ceramic adhesives, and a high temperature former could be great in terms of not being able to burn up a driver. The current failure is in the insulation of the wire, or the adhesives. This mentioned combination would literally push the limits from around 600F with current adhesives/insulation to upwards of 1000F. You'd essentially have a coil where the DCR would rise so much you couldn't deliver any more power and not be able to burn up the coil.
Several of these companies have tried it and found it not at all suited for the reasons i mention. Others simply looked at the addition of any nickel and it's magnetic properties. I'm sure it could be done, but the issue would be the drawbacks. If you FEA it statically with say the 27% nickel clad copper wire in the gap, you can easily notice lots of stuff happening in the gap at different points of the travel. I don't have the ability to FEA it dynamically and see the effects that the moving coil has on the flux field, but I would imagine the effect is far from positive.
John
Re: Re: Re: Re: Re: Re: Re: Re: Interesting Paper from 18Sound
John
Thanks. 27% is very high. I found that 6-8% was about the optimum for resistivity and resistance changes.
I understand about the centering problem, its what a physicist calls an unstable equilibrium. Like balancing a pencil on its tip. In theory it can be done.
Funny how I never thought about the nickel being magnetic - completely missed that one.
I know that Doug Button found an exotic alloy that did the same thing (but not magnetic), but it was not feasible to manufacture because of the elements involved.
Why is Nickel required to use ceramic coatings?
John_E_Janowitz said:
John
Thanks. 27% is very high. I found that 6-8% was about the optimum for resistivity and resistance changes.
I understand about the centering problem, its what a physicist calls an unstable equilibrium. Like balancing a pencil on its tip. In theory it can be done.
Funny how I never thought about the nickel being magnetic - completely missed that one.
I know that Doug Button found an exotic alloy that did the same thing (but not magnetic), but it was not feasible to manufacture because of the elements involved.
Why is Nickel required to use ceramic coatings?
Re: Re: Re: Re: Re: Re: Re: Re: Re: Interesting Paper from 18Sound
Hi Earl,
It's been awhile since I talked to the people at Ceramawire, but I somewhat remember the basics. Apparently the ceramic coating will insulate the wire from a physical/electrical standpoint, but is not an air tight coating. As the temperature rises above something like 500-600degrees, the copper oxidizes much quicker than at lower temperatures. I just sent an email to them again to get a more accurate response on the reasoning. You can see info on the wire itself here:
http://www.ceramawire.com/techspec.html
John
gedlee said:
Hi Earl,
It's been awhile since I talked to the people at Ceramawire, but I somewhat remember the basics. Apparently the ceramic coating will insulate the wire from a physical/electrical standpoint, but is not an air tight coating. As the temperature rises above something like 500-600degrees, the copper oxidizes much quicker than at lower temperatures. I just sent an email to them again to get a more accurate response on the reasoning. You can see info on the wire itself here:
http://www.ceramawire.com/techspec.html
John