Question About Voice Coil Temperature/Resistance

[RedJacket]

Let's say a material has a higher inherent resistivity to start out with (say 2.57 x 10^-7 Ohm . m, which is an order of magnitude higher than Copper's 1.7 x 10^-8 Ohm . m). But in the same temperature region, the resistivity of this material increases at a rate lower than Copper's, meaning it has a lower Temperature Coefficient of Resistivity.

My question is if this material has a higher specific conductivity (conductivity:mass ratio) than Copper and Aluminum, will it perform better as a voice coil, in terms of efficiency, sensitivity, thermal, and magnetic compression?

Basically, I'm trying to learn what the benefit is to a lower mass voice coil (with higher resistivity, lower TCR, and higher specific conductivity) vs. a higher mass voice coil (with lower resistivity, higher TCR, and lower specific conductivity).

Thanks

 

[PENG]

Let's say a material has a higher inherent resistivity to start out with (say 2.57 x 10^-7 Ohm . m, which is an order of magnitude higher than Copper's 1.7 x 10^-8 Ohm . m). But in the same temperature region, the resistivity of this material increases at a rate lower than Copper's, meaning it has a lower Temperature Coefficient of Resistivity.

My question is if this material has a higher specific conductivity (conductivity:mass ratio) than Copper and Aluminum, will it perform better as a voice coil, in terms of efficiency, sensitivity, thermal, and magnetic compression?

Basically, I'm trying to learn what the benefit is to a lower mass voice coil (with higher resistivity, lower TCR, and higher specific conductivity) vs. a higher mass voice coil (with lower resistivity, higher TCR, and lower specific conductivity).

Thanks

You talked about higher resistivity, then higher conductivity, and then back to higher resistivity in the end. Please clarify which one it is. Also, unless I am missing something, you can't have higher resistivity and higher conductivity (specific or not) at the same time but that's what you seem to be saying in your last paragraph.

If the resistivity is 2.57 x 10^-7 Ohm.meter, that's more than 10X that of copper. In that case it is not going to work well with most SS amps regardless of whether there are other benefits or not.

 

[RedJacket]

Hm - I think the specific metric I am referring to is ampacity/current carrying capacity. In the same mass, this material carries 4x as much current as copper

I'm trying to understand how important is specific conductivity and ampacity for voice coil materials. Would increasing one or both properties have any effect on sensitivity, efficiency, thermal and/or magnetic compression effects?

 

[PENG]

Hm - I think the specific metric I am referring to is ampacity/current carrying capacity. In the same mass, this material carries 4x as much current as copper

I'm trying to understand how important is specific conductivity and ampacity for voice coil materials. Would increasing one or both properties have any effect on sensitivity, efficiency, thermal and/or magnetic compression effects?

So you are talking about ampacity/weight, thanks for the clarification. Even if it is 4X better than copper, if its resisitivity is more than 10X higher, it is still going to be a problem for typical solid state amps that are voltage limited such that they can handle 16 ohm loads but not 25 to 40 ohms. Also, lower mass if great but how about volume, Al is also much lighter than Cu, but for the same ampacity, the diameter of AL wire will obviously be much larger than that of Cu. The same would apply to the material (presumable some sort of alloy) you have in mind. It is hard to comment on this really, without knowing every known properties of the material you are referring to. Resistivity and ampacity/weight is not enough.