76.118.146.246
In Reply to: RE: !2AX7, octal replacement? posted by tesla on November 05, 2009 at 06:36:31
There are two octal equivalents to the 12AX7 the 6F5 and the 6SF5. The mu is the same at 100 and the Rp and transconductance are very close. The 6F5 uses a grid cap which would add to the complexity of the mod. But either should work fine in a circuit designed for a 12AX7, including the RIAA since the Rp is almost identical.
I would suggest that this would not be a practical approach for a retrofit; it would make much more sense for a new design. That said, right now Antique Electric Supply is selling the 6SF5GT for $4.32 so it would be a cheap to try a few. It would be a PIA to build 8 adapters though. If you are really curious, why not build a couple of adapters and try them out to see if you like the sound. Make sure you use the adapters in the same stage of both channels. Start with the last stage of both channels, for instance.
Experimenting with new tubes and ideas should be part of the hobby. Get yourself a good tube manual and you will come up with lots of new ideas.
Follow Ups:
Post a Followup:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2009, Audio Asylum, all rights reserved ]
[ Go Green ]
[ Take5 ]