Hats off to Richard H. Mak for implementing this VTA/SRA tuning tool using the IMD-measurement approach!
In theory this is easy but very hard to get right in practice. Before this tool shows up, many times I have tried to do various IMD measurements but could not get meaningful correlations between the SRA and the data collected, due to noisy data, etc. He managed to build a team to implement the right algorithm and filtering to get clean, usable numbers. So far I have confirmed that as I adjusted the arm height to change the SRA, I can actually get a knee point in the IMD curve and then binary search for the best possible setting. Also, the solution it gave is only slightly different from the original setting I got using a microscope, but the sound has greatly improved. Great job!
這個微調 VTA/SRA 的工具真的可用！太強了! 而且真的找到比用顯微鏡得到的設定還要更好聲音的點。我之前想要測量 IMD， 都得不到乾淨可用的數據，Richard 居然辦到了。目前的版本還有些缺點，但能到此地步，已經非常不容易。
Using Acoustical System's head shell with adjustable VTA/SRA, I've again confirmed the VTA-tuning function of the AnalogMagik tool. When the SRA is about 5-degree off, the IMD numbers jump to almost 20%! Adjusting to reach optimal numbers, I measured the SRA at about 92.2 degrees. Note that the contact line/cantilever angle has previously been measured at 110 degrees with a microscope. The sound is now highly detailed while very relaxing.
用 Acoustical Systems 可調 VTA/SRA 的唱頭蓋，確認了 AnalogMagik 的調整 VTA功能，的確很厲害。當SRA偏離5度時，IMD 會到 20%！調整到 IMD 數值在5以內然後取得最佳值，這時得到SRA約92.2度，如圖3（線/桿夾角已經測出為110度）。此時，聲音的細膩度極佳。