In Reply to: phono amp question posted by horny on March 20, 2012 at 10:22:55:
for any of the various " RCA phono style" circuits: grid resistance of either tube is assumed to be very high, so same general response...
you have to examine how the stages are set up, because you may find that the stages are cascaded with in the same tube, and you will need a twin triode with different triodes in same envelope (i.e. 12DW7 or equiv)...
Also generally, if you can just sub the tubes, I would try 12AY7 first, because it has lower gain: 40 vs. 100 for 12ax7, and it sounds better generally, with some versions sounding very good..., than a 12au7 wherein even the best versions sound only good...mmmm ( with usual correct bias changes for 12ay7, etc) ok???
Ok, thanks Good Luck to you,
-3db
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Follow Ups
- phono amp question yes generally this is OK - Minussss3db 11:15:46 03/20/12 (9)
- RE: phono amp question yes generally this is OK - horny 13:59:13 03/20/12 (8)
- RE: phono amp question yes generally this is OK - Lew 08:12:07 03/21/12 (2)
- RE: phono amp question yes generally this is OK - horny 09:57:50 03/21/12 (1)
- RE: phono amp question yes generally this is OK - Lew 10:54:51 03/21/12 (0)
- RE: phono amp question yes generally this is OK - danlaudionut 15:43:27 03/20/12 (4)
- RE: phono amp question yes generally this is OK - horny 23:23:34 03/20/12 (1)
- RE: phono amp question yes generally this is OK - danlaudionut 23:27:36 03/20/12 (0)
- Good Evening Horny....yes thanks for the schematic... - Minussss3db 20:57:38 03/20/12 (1)
- RE: Good Evening Horny....yes thanks for the schematic... - horny 23:27:52 03/20/12 (0)