WA-67 full upgrade
We are proud to offer a full upgrade path to the WA-67, once again this is an upgrade where you send in your WA-67 tube microphone, 7 pin cable, and power supply. We fully rebuild the system to the highest standard we can, end to end, and cover return shipping back to you via UPS GND/Signature Required. This comprehensive upgrade makes the microphone all it can be. Less thin/tinny/strident, less ringy/resonant, cleaner, clearer, more open, more full, warm, and musical, while still retaining the certain '67 bite' that the mic should have... We make it sound far more expensive than it is, and rebuilt it to last a lifetime.
PSU:
Steel washers added to reinforce the channel frame of the mains transformer.
All electrolytic capacitors replaced with highest performance/longest life Nichicon and Panasonic parts
Full film capacitor/multilayer ceramic capacitor bypassing on all electrolytic caps
Special adhesive put down on all capacitors and on the regulator heatsink to eliminate any vibration/microphonics/parts coming loose over time
Entire board re-flowed, cleaned, all wire terminations stripped and re-soldered, wire lengths and ground paths shortened where possible
Fuse and LED lubricated, re-seated
Filament voltage adjustable regulator re-calibrated after burn in to -6.2v (approx) to extend tube life
Full solder re-flow on all board components, key wiring is replaced or re-done, tidied up.
LMT317 regulator is briefly removed to add thermal paste and then tightened back on to heatsink, and regulator is re-calibrated to -6.2vDC.
On many of the newer WA power supplies, a solidcore wire lead LED is used in place of the screw-in LED or incandescent bulb. Overall, I think this is fine; but we have seen with many that the two leads can be in close proximity to one another, and so to avoid any issues down the road we re-seal both leads with a couple layers of heatshrink and then use some short pcs of heatshrink to 'set' the proper depth of the bulb and then again to lock in its depth from the ouside (so it cannot pull further out or in), then we use a touch of adhesive to lock it down and more heatshrink overall outside to reinforce the brittle LED enclosure.
Microphone:
Generic capsule is replaced with our own custom made high quality, historically correct K67 capsule.
If applicable, the capsule mount is replaced with a less resonant capsule mount (as needed).
Capsule mount and saddle are replaced as needed with higher grade/low resonance parts (as needed, because some units are OK and others need these parts to be replaced).
Stock tube is replaced with an EF86 tube that we install, which is graded for low noise/low microphonics, which will be either new production EH or TAD tube, or NOS Winged C tube. If we use a new production EH or TAD valve, it is third party tested to be microphone grade. If we use a NOS tube, we personally clean/de-scale the tube and perform a listening test to grade for low noise/low microphonics. The original tube is returned in the return packaging, and is a suitable spare tube as long as it was in working order when it arrived to us.
Tube is fitted with a pair of Sandy Levy aerospace silicone tube damper rings to reduce microphonics, and a foam neoprene pad against the back of the PCB to insulate it from the PCB. Tube pins are lubricated with DeOxit Red before insertion.
Additional adhesive put down on polystyrene capacitor networks to reduce microphonics
Dedicated ground wire added to microphone chassis/XLR lug to improve ground contact
Capsule is replaced with upgrade custom made K67 capsule for better sonic performance
7 pin cable is rebuilt on both ends and optimized for the WA-67 specifically
Cable:
Cable is rebuilt on both ends to ensure quality and reliability, putting heaviest gauge wires on heater+ and heater ground where they are the most effective, and stripping back the jacketing and woven shield only to the bare minimum needed, to ensure proper RF rejection and cable durability.
System:
Microphone is burned in for 24 hours then re-calibrated, re-tested, and packed up. Heater voltage is given a final recalibration to -6.2vDC after tube selection and sufficient burn in, and with the same 7pin cable attached that it will ship out with.
