9/9/2023 0 Comments Nakamichi tapedeck![]() ![]() The idea is to shield the transformer from the Logic/Power board below. He also suggested the use of mu metal sheets to solve the 60hz hum issue, which is seen in some Dragons of any age and serial number. I was later told by Perry that this is a common fix. Copper sheet did not work, but an antistatic bag did! So an antistatic bag now lives in my Dragon. I solved that REV issue by trail and error, first attempting to reroute the head wires, which was picking up interference from the NAAC board, to trying to shield the two boards. Now I have two final problems holding me back from a great sounding Dragon: the 60hz hum, and a strange issue where if the NAAC board was screwed down, there will be a high pitched noise in the left channel in REV play. This made all the difference, better than MAX4066! High frequencies are improved, soundstage, channel separation. At this point I did the NAAC VR701/702 alignment. I feel like the noise floor is slightly lower, the sound a little more transparent, "richer" I would call it. This might be because the original polar Nichicon KS is already very good! I also changed the 2.2uf in the playback path. Not a big difference, but it is required for the new opamps. No real difference in sound, but motor feedback noise went down. The sound improved immensely with just this mod, opening up the veiled high end that was there even in source mode! ![]() LTC circuit and MAX4066, waiting for the ANT4066 to arrive: I also did WAV recordings of playback in each stage of the same song, I will upload that later.ġ. Each of the mods was done incrementally so that I can hear the difference. Since I'm impatient, I decided to do the Level Translation Circuit for the 4066 and try some MAX4066. While the new caps did help the motor noise, the 60hz hum was still there. Alex suggested some opamp upgrades, and I decided to recap the power filter caps and the motor board filter cap to reduce a 60hz hum and motor feedback noise in playback. While all this was happening, I was waiting for the ANT4066 chips. I had been looknig at the NAAC board, while the phase adjustment pots were on the Main Audio board instead! There's 2 sets of pots with the same name on the Dragon. Then I realized I was an idiot and had been looking at the wrong VR701/702! I spent some time reading the procedure in the manual, and wondering what the heck VR701 and VR702 did was they seemed to be for the meter calibration, and wondering if they were shared with NAAC in some weird arcane way (cue staring at the schematic). So I asked Perry for help, and he mentioned the phase adjustment on VR701/702. However, With CN-5 connected, it was still not perfectly in phase in REV. It was still perfect, so I did not touch it. A 4 track auto reverse that keeps azimuth in both directions mechanically with NAAC off.Īt this point I also checked the REC head azimuth. This is amazing to me, coming from Walkmans. Adjusted it slightly to perfect phase in FWD, and when I flipped the azimtuh tape over, it was in phase in REV as well! also conformed with my Teac 10K. I disconnected CN-5 (NAAC motor) to check the default azimuth. On a good deck, these two azimuth tapes always agreed with each other, or got very close. I got the same results from my secondary azimuth test tape, Teac 10K. ![]()
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