Lew,
I've been off skiing for a week, hope this is still helpful. The following is true for all models where we've made a comparison (Airy 3, 4D and UNIverse)...
COIL MATERIALS
X (copper coils): fastest, most macro-dynamic, most micro-dynamic, least slurring of leading/trailing edges, lowest sound floor, greatest "snap"
S (silver coils): less so (analogy: turns a ZYX into a Benz)
G (gold coils): much less so (analogy: turns a ZYX into a Koetsu)
OUTPUT
Low Output/.24mv (but ZYX uses a non-standard test record, so use .35mv for calculating phono stage gain requirements): see the characteristics ascribed to copper coils, above
Hi Output/.48mv (but ZYX uses a non-standard test record, so use .70mv for calculating phono stage gain requirements): see the characteristics ascribed to gold coils, above
WHY?
It has NOTHING to do with conductivity or other electrical properties of the coils. It's simply a function of their mass, in which:
Gold > Silver > Copper
Hi output (2X as many coils) > Low output (1X as many coils)
Reducing the moving mass of the coils on the armature reduces its inertia. Result? Faster responses, less slurring, greater amplitudes.
CONCLUSION
For any given ZYX model, the fastest, liveliest, most dynamic sound will come from the low output version with copper coils (and the SB weight). The slowest, softest, least dynamic sound would come from a high output version with gold coils (and no SB weight).
This is not theory. It's derived from comparative listening and thinking about why we heard what we heard. The differences were very easy to discern.
***
Ldvalve's description of the sound of a nuded UNIverse sounds much like our review of the UNIverse II, which is a semi-nuded UNIverse (UNIverse in 4D body).
