SP30, ST31, ST33, GT predecessor mod

Occasionally in our pro audio travels, we come across a diamond in the rough, and we've had a guilty-pleasure/secret infatuation with this ubiquitous GC-owned mic brand for several years now.  These are indeed good potential workhorses and diamonds in the rough, and their legacy line of products (just as good as their current line, aside from cosmetics in our opinion) can be found for incredibly low prices on the used market; but these diamonds do need polishing!  That's where we come in.  After more than 3 years of tinkering with various Sterling products, we're ready to make our recommended mods official; and the good news is they don't break the bank.  These mics may not appear to be much out of the box: bright, shrill, harsh, lacking bottom end, weight, and depth...  that's why you will be as surprised as we were to learn that these can be transformed into really well balanced mics that actually inspire confidence and performance!

The legacy SP30, ST31, ST33, and its Groove Tubes predecessor are all variations of the same SDC mic.   In my opinion, there is no quality difference between the 3 models or the more shiny/modern looking current offerings sold at GC; if anything the older ones may have been a little better constructed, as things have a tendency to cheapen with regards to materials and parts.  They work the same, sound the same, and the mods I perform are the same.  So, finding a good deal on a used one of these models and then having it updated by us, can be the deal of a lifetime.  You'll have an absolutely unbeatable SDC mic that holds its own with anything out there, and is a very good substitute for the venerable KM84 and others.

The first time I heard Sterling mics, I felt there was potentially something really good there.  Even though the mic was overly bright and shrill and harsh, and lacked real bottom end; something about it came through that told me it could be sort of saved from itself.  Because aside from that, it sounded and felt solid; and didn't suffer many of the hallmarks of cheap asian mics that I consider to be dealbreakers.  The main problems can be summed up simply: too much top end, and not enough low end.    There is some engineering going on, but not proper voicing.  

The lack of bottom end mostly has to do with the poorly done Chinese output transformer used in these mics.  It just doesn't pass all of the available low end, and seems to have a higher output impedance than a a properly wound T8-style transformer should.  We worked with our partners to commission our own T8 part for the mic, that has the right amount of bottom end and also just a bit better articulation and less 'smear' that is sometimes associated with cheaper magnetics.  I'll definitely give it to Sterling; they find a part and they just go with it.  Every mic I've evaluated is based on the same kind of transformer, same kind of tube, same kind of capsule... All the better for us; it allowed us to make a small run of custom transformers that can service any of their microphones.  So we remove their transformer in place of our own, carefully re-wrapped and put back into the internal sheild cannister, with the wire leads kept as short as possible and twisted in pairs.  

Because each of these mic PCBs are populated a bit differently, it's impossible to make statements as to semiconductor replacement... We've opened up ST51's with completely different (even in color) PCBs, and all 3 have a somewhat different PCB, populated differently.  I've opened up one that was all WIMA film caps and decent quality mica caps and electrolytics, and one that was all generic where I replaced a number of things.  Suffice it to say, we will do what is necessary to make it sound better.  We always replace every electrolytic with a Nichicon BLUE or GOLD audiophile series cap, and we always replace the generic MICA capacitors in the filter sections (which tend to go out) with over-spec'd 630v silver micas that will never fail, and we put in quality polystyrenes where applicable.  If we see a WIMA film cap in the floating high-z section where there should be a polystyrene (and we did, on one!), then we will correct that.  If everything looks decent, we will not.  I will say that on at least every one I've opened, I did at least replace the cap in the high z section to a polystyrene.  this allows the mic to be more open and less 'dense' or rigid sounding, and is the appropriate part to use.  

The $175 includes free return shipping to you, in the USA.  For an additional $40, we will include a 20ft Gotham XLR cable, made here in our lab; which truly helps bring the mic all the way up to its full potential.  International shipping, please inquire.