Its always a delight to find an old, relatively affordable mic that someone wanted me to mod, and to come to the realization that the mic really was done right the first time and didn't honestly need any help from me. Such was the case with the old Sterling ST77. Perhaps taking its name from the RCA ribbon mic of the same name, I can say that, in broad strokes, it does actually give off some of those warm, big, intimate vibes, and sounds very different from the more 'airy' nature of other Sterlings.
I never knew much about the mic until I had one in the shop; but it really is a completely different animal from the normal family of tube and solid state Sterling mics that I normally mod. The thing is built like a tank and the body feels like it is made of heavy gauge steel. It is big, and it is heavy. It's capsule design is all together different from what I'm used to seeing on the other Sterlings. Rather than the fragile and unpredictable quality 3 micron K67 with 'disc resonator' tuning baffle added, these mics sport a hefty, 8 micron custom K67's with no tuning baffle. And they are mounted on a VERY solid and stable mounting saddle, with none of the notorious 'knocking' that we always see with the standard Sterling mics. It not only has an extremely solid exoskeleton, even its internal framework is ruggedized and has additional bracing and support you wouldn't normally see, plus (as I mentioned), the most solid capsule mounting of any Sterling mic I've opened. The capsule choice is interesting (the 8 micron density hearkens back to the bygone era and gives things a more thickened, smoother tone... think less peaks, more sustain). They knew what they were doing, and it doesn't need replacement unless it has been damaged.
The circuit has absolutely zero electrolytic capacitors in the design... not just 'not' in the audio path... not there at all. I counted well over a dozen good tantalums and many good film capacitors, 'drop' style multilayer ceramics and other goodies, including a large film output capacitor. Lots of FETs. Everything appears rugged and well built.
The transformer, while certainly of Asian origin, seems well made and is very much over-sized, way heftier than what you'd expect, and is housed in its own shielded metal can as part of the mic's internal structure. As best as I can tell, it is a 3 or 4:1 step down, and plenty big enough and with plenty low enough output impedance that I have no doubt it can can pass deep low end without a problem... and that's really all you can ask. With the lower turns ratio and the fact that its a feedback design, the sonic influence of the transformer beyond that is likely very small. If it can 'not' be a bottleneck, then you're good; and this appears to be more than good enough.
I didn't realize until I looked it up; but this mic used to sell for $999 USD when it was in production, and I can understand why. It really may have been their flagship. To my tastes, it has the 'voice of god' type character that I love (deep and rich), and may just be the best mic Sterling ever made, at least if that sound suites your tastes. The only caveat I will give it is that it (particularly the headbasket) isn't very attractive. It looks and feels overly bulky and has a 'heavy, yet imported' vibe. If you can get over that, then you have a fantastic mic for the mic locker.
Not everything for me is about making a sale. Sometimes, I find something that needs no help from anyone and I just want to share the good news of this of it as a public courtesy. This is such a mic. If you can find one of these gems at a good price and in good working order; this is well worth owning. And it does not need to come to me or to be modded by anyone else, regardless of what any other website may suggest.