I think I have finally replied to the age-old question: “Can a low output MC be amplified with an all-tube system and within a high efficiency environment, with no noise at all?” The answer is a resounding “Yes”, although I had to persevere for a long time trusting my instincts, against most of the people I know! These said, not without reason, that with the system and MC (just 0.25 mV output for my original Transfiguration Temper) I had, I’d rather stay with transistors…Now, they eat their hearts out!!!
My research on this matter began almost 7 months ago, when I first took a closer look at the CORNET phono stage. According to the many people who had built it (many references in Audio Asylum), the thing was cheap, glorious sounding and…dead silent. This was a good start, although the term “cheap” must be related to the components used and the quality of the chassis. Still, I bought the nicely made board and, after some thought, let it rest for a while…
What I did, instead, was to hard wire the very simple circuit with components I already had in my stash, just to make sure. Well, these guys were right…The amp (coupled to my vintage Conrad-Johnson premier 6 nuvistor pre-pre amp) was indeed glorious sounding, although some tube hiss persisted (normal).
So, I had to use step-up transformers and my previous experience with these was not at all conclusive. I mean, in the past, I have tried to amplify a similarly low-output DENON 103 with its proprietary transformers and the results were more than catastrophic i.e. the music was as if robbed of its dynamic content. This time, I had a gain of 44dB in the MM stage, so a quick calculation showed that I needed a transformer capable of 1:30 amplification. Enter the LUNDAHL 1678 and my luck which began smiling, as the importer is a friend agreeing to take them back, if they did not work to my total satisfaction. But they did more than satisfy me and, as a result, I bought the pair…
From then on, I began “hunting” components to optimize the whole: As you can see, I have found a very nice copper chassis on Ebay and also purchased a whole bunch of Riken-Ohm carbon resistors, teflon, oil-filled and paper caps, silver wiring…the works! For a detailed inside view, please see this
picture Finally, I have installed 2x CV4004 & CV491 Mullards and tested a number of rectifiers, before settling for a M.O.D. CV378 blast from the past. Vinyl rediscovered!
UPDATE (30/05): MULLARD 4004's replaced by ECC83's TUNGSRAM. Better still...
