Can I replace 6n2p with ECC85?

kyonthinh

Active Member
Hi,
I have a little bear t10 phono preamp with 6n2p/12ax7 tube choice. I got some ECC85 and tested and it worked good, sound better than my 6n2p EV. But can I really use it? Will it make my amp kaputt?
Thanks.
 
The tube can work, but has less gain than a 12AX7 AND the filament wiring is different. The filaments are paralleled in the tube and there is no filament center tap. The ECC65 requires 6.3 volts, not the 12.6V used by the 12AX7 with the filaments in series.
 
It has a switch to choose 6n2p or Ecc83 filament. 6n2p has 6.3v and same wiring with ecc85, but I dont know about the difference between them.
 
Well then, sounds like that will work, since the re-wiring has already been done for you to have tube flexibility. From what I read, the ECC85 will work with somewhat less gain. Just google it and you'll see what I'm seeing. Good luck!
 
Watch it with the12AT7. It's not really an audio tube, and can become microphonic, plus plate and screen voltages that are ok for a AX7 may not be ok for a AT7. Plus it's a fairly noisy tube and not really recommended for Audio Gain stages. Go ahead and play with it, but I think you'll be going back to 12ax7's. One tube you CAN USE is a 5751. It's a 12ax7 with gain of 70, just like the 12at7. As it's a 12ax7 derivative the heaters are the same.
 
If they are cathode followers, gain won't matter so much. the delivered gain might be .8 vs. .85 or so.
cheers,
Douglas
 
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