I also get asked a lot what the differences are between the standard and ultimate upgrades for the WA-47 are, so I decided to paste an email from today explaining those things...
"So, the standard mod, the one I came up with after leaving Warm and moving back to Baton Rouge, just corrects the personal voicing and QC issues I had with the mic in the way it was released. It puts a better tube in there, puts in all better capacitors in the mic and power supply, cleans and tidies up things a bit, puts in a vintage network of PIO output capacitors, and makes it a touch quieter, cleaner, more dynamic and responsive, and 'fills in the cracks' sonically so that it sounds deeper, fuller, more natural, warmer, a good bit less phasey; but overall still retains the sort of 'warm and fuzzy' vintage character that the mic had originally. It's for people who like the sound of the mic now; but just want it to 'do that thing' even better yet and to be built like a tank and cleanly opposed to being of more 'mass production' quality. It makes it basically what I originally had hoped and envisioned it to be, and I really stand behind that mod.
The Ultimate Upgrade is more like me building a new mic for you inside of that framework, using the same boards, transformer, and capsule; but literally replacing every single other component in the microphone, including even all the wiring which is replaced with Belden's finest grade Silver Teflon wire. Every film capacitor, tantalum, polystyrene, and even RESISTOR is pulled out and replaced with the most optimal part I can find. I use some carbon resistors, some metal oxide resistors, and in places where noise needs to be reduced I actually put in some custom made resistors from Precision Resistive Products that reach noise levels right at the theoretical low limit. Both the tube board and main board are fully stripped down and de-soldered, and re-vitalized by submerging them in PCB cleaner using an ultrasonic cleaning bath. They are then meticulously repopulated by me and the mic rebuilt. The transformer is direct wired, bypassing the lower deck PCB entirely. I put in the best tube I can, and put in a VERY VERY expensive new output capacitor by Solen (metalized polypropylene) which is designed to convey the depth and fullness and 3D aspects of my favorite vintage capacitors without any of the potentially negative attributes. The results are just stunning. It's a new mic, built in the old boxes. It has a drastically cleaner, more polished, more up-front and ever slightly more mid-forward sound without sacrificing any of the top and bottom. I worked on this for a long time. It's pretty intense, and may be overkill for some; but for people who want it to be the VERY best that is possible, this is that mod; and so far, everyone who has ordered it absolutely LOVES it. "