The 500 Series mic preamps I used on Old Man Saxon and the new group Royalties were my own custom design. Discrete, no IC's and loaded with transformers. I've made a limited run of the circuit boards and you can buy them from me for damn near the cost of manufacture. Just hit me up.
They employ the Deane Jensen 918 opamp (or 990 if you want to go cleaner) available from CAPI and DIY Recording Equipment. The ones I use have hard-to-get vintage Pacific Recorders 918's that I found on eBay. In/Out transformers can be Lundahl, Jensen or Cinemag. There's a DI input that auto-switches when you pop in an unbalanced guitar cable. It's what I run my MPC, Drum Brute and Moogs through. Sounds pretty fn amazing. The DI is transformer-based (any of those 3 aforementioned brands plus the lower cost, German made Pikatron) making a grand total of 3 transformers in this unit. BEEF! Phantom power, pad and phase flip are activated with dope looking illuminated pushbutton switches. If you want some PCBs, hit the contact button and drop me a line.
I'll soon be slanging these fully-made, plug-n-play.