As always to be clear, this is an upgrade where you send us your ART T4 Tube Microphone, cable, and power supply.  
 
Once upon a time, there was an Asian tube mic circuit called the Alctron MK47, and boy that circuit did get around.  LOL  it has shown up as the Warm 47, Weird 47, ART T4, a couple other even smaller names, and even shown up in mostly in the Asian market as the Alctron version.  Electrically it has more in common with a C12 than a 47; but it generally does have some sort of K47 or M7 capsule added and some voicing updates which put it more in the 47 range.  Ultimately its a tried and true circuit which seems to have good field reliability and has been employed by quite a few manufacturers to be their flagship 'tube mic' offering.  Each time we see the circuit, it is always 'tweaked' and modified to the client's request to some degree, although this iteration and the ART model are for the most part 'untouched' and identical to original generic Alctron build that we've seen so far.  It appears that Weird Audio may specify a certain capsule, and it doesn't appear that ART specify any changes at all aside from paint job.
 
We have modifed our approach to the WA-47 to accommodate these 2 new additions, taking into consideration the fragility of the design and the additional space constraints presented.  We rebuild the mic fully from end to end, replacing everything in the PSU, installing our discrete regulator, rebuilding the cable, and upgrading the heck out of the micrphone circuit.  You can read more about the upgrades to the PSU and cable by looking at our WA-47 upgrade specs; so I'll go over what is unique to the mics here:
Due to more limited space constraints, we do not use a paper-in-oil NOS capacitor network for the output coupling, instead we upgrade the stock generic 1uF film cap to a JB JFX series 1.5uF film cap (our absolute favorite of any modern film capacitors, hands down... closest thing you'll get to vintage quality in a modern build), and replace the two electrolytic 1uF caps in the mic board with JB JFX 1uF film caps.  The 100uF generic electrolytic cap is replaced with a name brand tantalum capacitor.  The generic film cap strapped across the capsule termination is replaced with a name brand polystyrene capacitor of the same value, and acoustic dampening adhesive is applied to reduce microphonics.  The generic Chinese 7025 valve is replaced with a TAD Germany 5751 Highgrade valve, which we select and burn in, and the tube is fitted with a pair of silicon dampening rings and the pins are lubricated before insertion.  We add a dedicated grounding wire to the mic chassis, and we check ground continuity across the main mic hardware components.  The rudimentary low pass RF filter is removed from the mic's XLR output (because it degrades the sound) and instead we address RF concerns by adding a ferrite to the capsule backplate termination (which is a much more sonically transparent way of addressing the issue in most cases).  
There are more proprietary steps that we take; but this is the general rundown.  We look forward to letting you take your Weird or ART 47 mic out of the closet and bringing these beasts back to life with renwed energy and sound quality!