The AU7 is a great vacuum tube and
Well known for its a low noise , and part of double triode family. It Is used either in 6.3 V at 300 mg what 12.63 50 mA in a heater circuits for both PreAmps and Amplifiers.
That said I will address Gerad’s question: You can use the 6211 in the Eclipses. This tube is more like the 12AT7 with a lower gain than both the 12Au7 and the 12AT7. The construction of this tube makes it as as very desirable tube because it tends to be more ridged, robust, and very mellow. Make shure when purchasing that they are tested for Microphonics.
Gerard, if you can find a matched pair of Telefunken 6211; grab them! Some of my colleagues have claimed better bass response from these tubes.
Good luck and enjoy the music
MP1968,
The ECC80 is a tube I have not come across, As I understand it was primarily made in Europe just like the ECC82 and we have made an equivalent via RCA, GE, Sylvania in our 12AU7. The ECC 80 from Holland would be something I would love to find or our equivalent 6085. I will tell you that I love the ECC82 from Holland and have absolutely enjoyed the sound of the Amperex tubes including the Bugle Boys. I'll try and get a better answer for you regarding the ECC80.
Until than enjoy the music.