Although I am not familiar with the Van Alstine mod I am familiar with the ST-70. The front end tube of the stereo 70 is the 7199, 6AN8 on the MK lll. That tube really needs to go. It's a medium mu triode/ sharp cut off pentode that's prone to hum and premature clipping of half the waveform and high distortion. There are a few mods out there that actually replace the circuit board and use 2 front end tubes insted of one. It also improves the coupling caps and resistors from the stock unit. There are also replacement boards for the multi-stage filter capacitor. The stock cap is a twist lock lytic and were of poor quality. Look at some of the mods offered by Joe Curcio and you will see what I mean. Hope that helps. Have fun. G
