This preamp has a lot of gain and when you add it to my new 180W Tripath power amp and two stage 12AX7 preamp I can barely turn the volume knob up. I cut away Ck on the last stage of the preamp to lower the gain but this did little. I was going to add some resistors to lower the signal level going into the preamp but then this adds to the output impedance.
Then I had an epiphany. I happen to have two JAN-GE 12AU7s (NOS) the type I have been using on my hybrid "Parley" tube and SS preamps. Nice tubes but not in the clear yet. Sure enough dropping in the "U" drop the gain to now a very workable level. Not only that but pots don't work well at extremes of their range. Now they work nicely toward the center of their range.
But the JJ tubes supplied have a very short plate, about 1cm. Great for low microphonics. My GEs have a long plate. I just ordered the top of the range Psvane 12AU7-TII gold pins. These have (at least in the photo) a short plate. And where I have Gold Lion 12AX7s in my current preamp I will swap them to the GEs when the Psvanes arrive. So less gain in the phono preamp and preamp. And a better tube.
The GE 12AU7s have a softer tone to the 12AX7s. OK for me but I can see why some like the crisper "X7"s.
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