I don't see four seams on the top of the glass so I say the two on the left sound better than the two on the right.
The silver Tungsram are made in Holland which is from a different location than the three different stapled plates so there's at least four different Tungsram locations that made ECC83. The easiest one to identify has four seams and is made in Austria.
I agree EI grey and silver plates sound different. Lesser known is the EI ECC83 short plate. For good reason. The worst of the three.
EI Short Grey Plates
1 93, 96 1960, 1800 80, 79
2 95, 99 1720, 1880 79, 80
3 99, 97 1780, 1690 79, 80
4 91, 92 1740, 1660 80, 80
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