by msmpe » Mon Jun 09, 2008 2:45 pm
I'm a beginner at this, but have done some research on phono tube preamps. Two things to consider are accuracy of the RIAA EQ and gain.
According to Eric Hayes in some earlier threads, 40dB is the minimum gain requirement. The 2-stage passive preamps will just barely meet that spec if pushed. The 3-stage is better suited in this regard.
With that said, however, there are a couple of good 2-stage MM preamps out there: RJM and Curcio's PWB-6. Both use 6922s and claim high accuracy, but gain for both is less than 40dB (38 and 30 respectively). The early Shure M65 and RCA 2-stage circuits were not the most accurate (see earlier threads), and I am not considering them any more. Although JE Labs has an interesting RCA knock-off by a guy who should have a pretty discerning ear. For my first MM phono preamp I'm working on RJM's circuit followed by a 2 stage line.
For some "beefier" circuits check out: Allen Wright's (VSE) FVP5A or RTP3C, Curcio's Sarah, Steve Bench's Cascode, and Jim Hagerman's Coronet2. You could also consider the Marantz Model 7 which is a 3 stage phono circuit followed by a line stage, and there are probably some other vintage hi-end circuits worth considering.
Nuther Nuby hooked on tubes