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Is a 12au7 a safe replacement for a 12ax7

Recently I tried the very low gain 12au7 tubes in my preamps phono section.
The reccomended tube for my phono section is a 12ax7.
Other then a huge difference in gain which is desirable the only difference is in heat dissipation.
The reccomended 12ax7 's dissipation is 1 watt and the 12au7 is higher at 3 watts.
I'm not technical ,so I ask
What is the downside of using a 3 watt dissipating tube in place of a 1 watt tube
Many thanks for your reply
goldeneraguy

Showing 1 response by yogiboy

yogiboy's avatar
yogiboy
5,504 posts
 
I had the same problem with my phono preamp. Too much gain
with the 12AX7 that should be used.
I tried a 12AU7 and that was not enough,so I tried a 12AT7 and
it is perfect with the output of the cartridge I use.
The gain factor of a 12AU7 is 19 and the gain factor of a
12AT7 is 60. BTW I never had a problem doing this in eight
years. So if the 12AU7 works for you don't worry about it.
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