I will describe the differrence of two coils before making a choice.
For coil 2, it has thicker wire (14AWG) and lower resistance. This coil is at woofer side. It mainly flowing low frequency current. However, if your speaker is a 2-way system, it will passing current up to mid-band and also beyond cross-over point slightly (>3kHz). Skin-effect in wire-type geometry will increase resistance at high frequency, though in theory it is very little, perhaps in the order of 0.001 ohm. So many branded loudspeaker would use wire-type coil for economic reasons.
In physics high frequency currents tend to flowing on surface (skin) of conductor due to complex dielectric and permeability related problem. Skin depth reduces and thus increasing resistance as frequency increases. Skin effect is talking about resistance of wire increase with frequency but only significant above 1MHz. Therefore, the effect in audio frequency is tiny. But some people says the resistance variation due to skin effect is considerable in the sense of magnitude difference across full audio spectrum (20-20kHz). For example, wire resistance is 0.0001 ohm (say) at 20Hz, the wire resistance becomes (say) 0.001ohm at 20kHz. However there is still nobody conducting an meaningful experiment on this issue. Theory is always correct. But in practical audio matters, it is no idea how skin effect plays an role.
For coil 1, the advantage of foil type geometry is better current transmission at high frequency, due to larger surface area of foil geometry than round wire of same cross-sectional area (AWG gauge). One would expect foil type has lower resistance rise at high frequency. The coil performs more linear across full audio band.
The comparison is obvious because two coil has different gauge. The DCR of the two coils are significantly different. I think DCR of coil 2 gives more advantage regardless of skin effect issue. For coil 1, the advantage in skin effect may be upset by loss in bass energy.
Coil 1 may sound more beautiful because of foil geometry and thus less variations in resistance across audio band. But maybe I have not enough concrete proof to support my hypothesis. Anyway you don't need to take my words so serious. Just be an experimenter and try.
Thanks ! |