Interesting post; thanks! And congratulations on the improvement you’ve realized to what was certainly an already exceptional system.
My feeling is that the root cause of the issue in this case may very well have been ARC’s choices of the gains provided by the Ref2SE, which seem a little strange. 51 db being too low for most LOMC applications (and too high for most MM applications), and 74 db being too high for most LOMC applications.
51 db represents a voltage multiplication of 355 times, which would raise the output of a 0.33 mv cartridge under the standard test conditions to only 117 mv. The very reasonable 12 db gain of your line stage would raise that to about 466 mv if the volume control were turned up to max, which would be much too low to drive most power amps to full power. While 76 db phono stage gain is typically best suited to cartridges having outputs that are considerably lower than 0.33 mv.
More typical for use with a 0.33 mv cartridge would be a phono stage gain of a bit more than 60 db, close to the 20 + 45 db you are now using.
Of course, you’ve changed several things in this process in addition to modifying the gain structure, i.e., inserting a transformer into the path; changing the load presented to the cartridge from 200 ohms to 470 ohms; and changing the interface between the phono stage and the line stage from balanced to single ended; and I suppose all of these things may have contributed to the resulting sonic differences to some degree.
BTW and FWIW, my 64 db Herron VTPH-2 seems to be an excellent match for my 0.5 mv cartridge. And during my discussions with Keith Herron prior to the purchase he indicated that the 64 db configuration of the VTPH-2 would have been a better choice for use with a 0.3 mv cartridge I was considering at the time than the 69 db configuration he also offers.
Best regards,
-- Al
My feeling is that the root cause of the issue in this case may very well have been ARC’s choices of the gains provided by the Ref2SE, which seem a little strange. 51 db being too low for most LOMC applications (and too high for most MM applications), and 74 db being too high for most LOMC applications.
51 db represents a voltage multiplication of 355 times, which would raise the output of a 0.33 mv cartridge under the standard test conditions to only 117 mv. The very reasonable 12 db gain of your line stage would raise that to about 466 mv if the volume control were turned up to max, which would be much too low to drive most power amps to full power. While 76 db phono stage gain is typically best suited to cartridges having outputs that are considerably lower than 0.33 mv.
More typical for use with a 0.33 mv cartridge would be a phono stage gain of a bit more than 60 db, close to the 20 + 45 db you are now using.
Of course, you’ve changed several things in this process in addition to modifying the gain structure, i.e., inserting a transformer into the path; changing the load presented to the cartridge from 200 ohms to 470 ohms; and changing the interface between the phono stage and the line stage from balanced to single ended; and I suppose all of these things may have contributed to the resulting sonic differences to some degree.
BTW and FWIW, my 64 db Herron VTPH-2 seems to be an excellent match for my 0.5 mv cartridge. And during my discussions with Keith Herron prior to the purchase he indicated that the 64 db configuration of the VTPH-2 would have been a better choice for use with a 0.3 mv cartridge I was considering at the time than the 69 db configuration he also offers.
Best regards,
-- Al