The PX-1 is a popular and very affordable large diaphragm condenser microphone by PreSonus. The microphone was designed to be a very cost-effective solution for hobby level and home studio recordists, and is quite rugged and well put together. Despite certainly being made to a budget, the mic has some really good attributes such as low noise and very little sibilance or unnecessary brightness, often seen in affordable LDC's. The microphone is manufactured by the same factory who make Sterling and other affordable mics, and therefore has much in common with the Sterling microphones we currently upgrade. While it may lack some of the energetic sound and top end clarity of the solid state Sterling offerings, it also lacks some of the problems that those mics have also, thanks in part to the simplicity in its design approach. Though it's low and top end reach don't extend out quit as far as some offerings, it is really neutral and balanced through the musical range, neither dark nor bright nor sibilant. It was voiced to be a basic universal mic with no frills, bells, or whistles; and I believe voiced by someone who knew what they were going for. I should add that the mic utilizes a cardioid-only K67 style capsule, which is a fairly good capsule for that price point. I believe it isn't constructive to critique a mic that is meant to sell for $130; rather, I should note that any mic at this price point that you can actually cut record-quality recordings with is somewhat a miracle of our modern age, because just a generation ago you could only get 'Radio Shack' microphones at this price point. It's a solid mic made for life on the go, and that its character is different from most budget LDCs is a big plus also.
What we do in this mod for this is to replace the output transformer with our own better constructed, custom-wound T8 transformer, which gives it a lower output impedance and a little bit better extended low end and low/mid body. We wrap the transformer in insulating tape, then foam, to securely pack it into the onboard sheild can, with the wire lengths kept to minimum and the output secondaries as a twisted pair. We also add a dedicated chassis ground wire to the XLR chassis lug, and tie to chassis at the frame. Also any screws or mechanical parts that need to be replaced or tightened up will be done, and locktite added as needed so that everything is very solid.
The board is cleaned up front and back, all components re-flowed and leads trimmed, boards brushed with alcohol, etc.; and all electrolytic capacitors are replaced and upgraded with Nichicon audiophile grade (gold or blue series, mostly) capacitors. Internal wiring is upgraded as needed to silver teflon wire. Capsule is inspected and, if needed, wire lengths shortened on capsule terminations.
The result is a version of the mic that sounds broadly the same; but is just slightly smoother and more pleasing on the ears, just a touch cleaner, handles transients just a touch easier, and with just a little bit of an extension to both its high and low end reach, and with a little bit better phase linearity at those extremes as well. The differences are not huge; but if you own one of these mics and want it to simply be the best it can be, or do not want to feel that you have 'outgrown' the mic in a few years but that it can still hold its own as you grow in production skill; then this mod will get you there and make the microphone a keeper.