The 6AC10 is basically three 12AT7/ECC81-class triodes in a single envelope. These have a mu ("gain") of 60, where the normal 12AX7/ECC83 has a mu of 100. You could use them in the same sort of circuits as 12AX7s, but the gain will be lower on any stages with bypassed cathodes.  Check out the following link for a discussion of some of these applications:   https://www.diyaudio.com/community/threads/6u10-6ac10-6d10-6av11.174631/

Location: B5

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