12BZ7 ///12AX7

mozartfan, The E80CC is a European designation for a tube. The European designation for the 12AU7 is E82CC and for the 12AT7 it’s E81CC, for example. I don’t know if there is an American designation for the E80CC.

Different tubes have different electrical characteristics. You need to check with the maker of your Defy 7 to make sure that the E80CC’s electrical characteristics won’t damage it over time. It’s really not a good idea to substitute different tube types without finding out if they’re compatible with the equipment.

I checked at Brent Jessee Tubes and it appears that the E80CC is considered a substitute for the E82CC with the caveat that you check with the manufacturer about suitability:

E80CC / 6085:This unusual European tube is basically an industrial type 6085. However, it’s specs are similar enough to a 12AU7 that audiophiles are grabbing them up while the prices are still reasonable. The heater life is rated at 10,000 hours, and some have gold pins. The larger box plate structure gives this tube low microphonics and silky smooth sonics. Since this tube has a much higher Gm and Mu factor than a 12AU7, the gain is going to be greater and this tube will give a more forward presentation. Awesome in phase splitter applications. If in doubt, check with your amp or preamp manufacturer to see if this tube will work OK in your application.

The 12bz7 is basically a double 12ax7, ie. Each 12bz7 triode is similar to two 12ax7 triodes in parallel. It draws double the heater current of a 12ax7 (600mA vs 300mA) and has twice the transconductance. It has a gain of 100, like the 12ax7. Not sure if your Defy 7 can take it, you might need to ask Jadis for help with that. If the circuit was designed for 12ax7s, dropping in a 12bz7 might cause the circuit not to work properly.
In the same way a 12bh7 is similar to a double 12au7 and also draws twice the heater current, and a gain of 20.
I used to use 12bz7s in my tube phono pre of the 90s.

+1 ndevamp.
Check with the manufacturer.

Jadis always *Please relate all concerns to our USA representative dealer*.
Bluebird, i believe, which is a dead end as for *~~cap I swap tubes,,,~~~
~~what we suggest,,,,,,~~ no doubt will be the answer..
As Blue and Jadis do not want to give the green light and if a curcuit blows, , can’t take the risk for blame..
Seems to me is the system is working with the E80’s, and no shorting/crackles, whistles, pops, then just let it play.
The Defy with AU’s does not offer the fq resolution, forward sound stage, that i require ina amp,.
= I am willing to risk possible issues.
EU E80CC = 12bh7, at least from looking at the 2 designs.
I just boughta bunch of bh’s along witha bunch of bz’s.
The bh’s i will try in the AU section and the bz’s in the Defy’s AX section, will post later this week how these 2 tube rolls went off.
maybe evena YT vid with the new bz’s and bh’s.

OK so the
12bh7 = EU E99CC.

~~Ck with your amp manufacturer~~~
(a bit late for the roll to the E80CC)
https://www.tubesforamps.com/products/12bh7