Siemens CCa: Gray and Silver riser differences

Has anyone heard both the silver and grey riser CCas. I understand that the only difference is the grey electrostatic coating on the earlier (mid 60s and earlier)shields. There is also the later 70s version with the wire getter support and it may be interesting to note how these sound as well.


Heavily affected by age. It's not the colour. The silver risers are the older, and much better sounding, tubes. Maybe the air was better in the plant. I have both and stick with the silver risers in my AA 3A.
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Slightly off-topic, but not really too far....Does anyone have a link to a diagram of a tube with various parts named; IOW a guide to tube anatomy.