An often overlooked Siemens and Halske Tube is the 1960's vintage ECC88/6DJ8. Extremely rare to test one that is not tightly matched between triodes. Just as rare for this tube to be microphonic and even the slight bit noisy. To top it off, no slouch at resolving low level detail, extended on top and bottom. My first choice for sensitive gain stage use in pre-amps.
Difference between Siemens CCa & 7308
Any significant differences between Siemens CCa and 7308 tubes of the same era? I know the CCa is highly regarded, hard to find and expensive. Seems the Siemens 7308 is a bit easier to find and slightly less costly. Does the 7308 give up much in performance? Thanks!