Hi Scott,
In the specific case of the Herron I would not expect using a SUT into its MM input to be preferable to going directly into its MC input. I say that in part because of the great results many have obtained using LOMC’s directly into the VTPH-2; in part because as I had mentioned I have found the VTPH-2 to be absolutely quiet at any volume setting (even when using my Stax electrostatic headphones, with the volume control at max); and in part because using a SUT into a 47K MM input will result in the cartridge seeing a much heavier load (i.e., a **much** lower number of ohms) than seems to usually be necessary with the Herron. (Keith recommends that with the VTPH-2 it is often preferable to apply no loading at all, with the input impedance of its LOMC input being almost infinite. And as Atmasphere and others have pointed out in past threads here, optimal loading of an LOMC is primarily dependent on the design of the phono stage, not on the cartridge).
To answer your question about gain, based on the relation db = 20 x logarithm(Vout/Vin) it can be calculated that for a 45 db gain setting of the Chinook the corresponding voltage multiplication is 178x, and the 43 db MM gain of the Herron corresponds to a voltage multiplication of 141x.
0.27 mv x 7 x 141 = 266 mv
0.27 mv x 13 x 141 = 495 mv
0.27 mv x 7 x 178 = 336 mv
0.27 mv x 13 x 178 = 625 mv
All of those alternatives would provide the 10x headroom factor Bob recommended, relative to the max input spec of the REF3.
Regards,
-- Al
In the specific case of the Herron I would not expect using a SUT into its MM input to be preferable to going directly into its MC input. I say that in part because of the great results many have obtained using LOMC’s directly into the VTPH-2; in part because as I had mentioned I have found the VTPH-2 to be absolutely quiet at any volume setting (even when using my Stax electrostatic headphones, with the volume control at max); and in part because using a SUT into a 47K MM input will result in the cartridge seeing a much heavier load (i.e., a **much** lower number of ohms) than seems to usually be necessary with the Herron. (Keith recommends that with the VTPH-2 it is often preferable to apply no loading at all, with the input impedance of its LOMC input being almost infinite. And as Atmasphere and others have pointed out in past threads here, optimal loading of an LOMC is primarily dependent on the design of the phono stage, not on the cartridge).
To answer your question about gain, based on the relation db = 20 x logarithm(Vout/Vin) it can be calculated that for a 45 db gain setting of the Chinook the corresponding voltage multiplication is 178x, and the 43 db MM gain of the Herron corresponds to a voltage multiplication of 141x.
0.27 mv x 7 x 141 = 266 mv
0.27 mv x 13 x 141 = 495 mv
0.27 mv x 7 x 178 = 336 mv
0.27 mv x 13 x 178 = 625 mv
All of those alternatives would provide the 10x headroom factor Bob recommended, relative to the max input spec of the REF3.
Regards,
-- Al