The first generation Z v.2 use a 4-layer aluminum coil -- specs listed below.

Newer Z v.2 use copper coils -- specs posted here :

http://www.caraudioclassifieds.org/forum/showthread.php?t=50823

D1 specs will be very similar -- D2 specs can be used to design the enclosures no problem.

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10" D2:

RE: 3.88 ohms

Fs: 51.69 Hz

Qes: 0.474

Qms: 7.04

Qts: 0.444

Le: 2.53 mH

Vas: 7.31 L

BL: 24.01 NA

Cms: 43.77 um/N

Mms: 216.53 g

Sens: 85.12 dB 1w/1m

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12" D2:

RE: 3.72 ohms

Fs: 37.54 Hz

Qes: 0.409

Qms: 6.82

Qts: 0.386

Le: 2.8 mH

Vas: 23.95 L

BL: 24.07 NA

Cms: 66.43 uM/N

Mms: 270.43 g

Sens: 86.74 dB 1w/1m

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15" D2:

RE: 3.8 ohms

Fs: 36.83 Hz

Qes: 0.376

Qms: 3.8558

Qts: 0.342

Le: 2.956 mH

Vas: 60.77 L

BL: 25.28 NA

Cms: 67.02 uM/N

Mms: 270 grams

Sens: 90.91 dB 1w/1m

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18" D2:

RE: 3.69 ohms

Fs: 30.21 Hz

Qes: 0.477

Qms: 7.65

Qts: 0.44

Le: 2.62 mH

Vas: 126.61 L

BL: 24.21 NA

Cms: 69.35 uM/N

Mms: 400 grams

Sens: 90.47 dB 1w/1m

The specs of z-12 v.3????? And z-10 v.3