Iron Cone vs Carbon Fiber Cone

I currently got two speakers without cones and four unused passive radiators, so I thought: why not use the passive radiators that are just front suspension and cones for the unused speakers?

The passive radiator weighs 60 grams which is heavy for a 6 inch woofer but suitable for a subwoofer, it is also made of iron which is unusual for a subwoofer and explains weight.

About the carbon fiber cone, it's just for comparison which one would be more suitable for the small subwoofer, at least I think carbon fiber cone is better in everything (weight vs stiffness & damping).

And about the motor (magnet), it must be able to move the cone since the original cone was more or less half the weight of the iron cone.
 
Yeah, I think it must be an alloy as a thin pure Iron circle would be horrendously brittle & crack at the slightest application of force.

---------------------------------------------------------------------------------------------------------------------------------------------------------------------Rick...
 
I currently got two speakers without cones and four unused passive radiators, so I thought: why not use the passive radiators that are just front suspension and cones for the unused speakers?

The passive radiator weighs 60 grams which is heavy for a 6 inch woofer but suitable for a subwoofer, it is also made of iron which is unusual for a subwoofer and explains weight.

About the carbon fiber cone, it's just for comparison which one would be more suitable for the small subwoofer, at least I think carbon fiber cone is better in everything (weight vs stiffness & damping).

And about the motor (magnet), it must be able to move the cone since the original cone was more or less half the weight of the iron cone.
Passive radiators are an alternative to bass reflex ports and are resonant/tuned, hence the extra mass (which would be too much for.a speaker I think).