I have acquired several budget and vintage SDCs which I considered interesting modification subjects. These include:
Gefell MV691/692 with M70 cardioid capsule: when I bought some studio gear a while ago, my son was delighted to find a vintage Gefell M70 capsule on an otherwise useless HH715 wireless microphone. Curious as we were about how this famous capsule with a nickel diaphragm would sound, I then wanted to complement the M70 with an MV692 preamp. I was lucky to get one for a reasonable price, and we could start recording. On acoustical guitar, we appreciated the sound of this microphone so much that we decided to keep it. I decided to acquire another two of them for modifications and direct comparison with an unmodified MV692/M70. I plan to replace the rather crappy PCBA with old-fashioned, noisy electronics with something completely new. And at the same time, make them P48 compatible. I intend to try three different circuits: transformerless, with the stock transformer, and with a modern, high-quality Lundahl transformer.
AKG P170: The AKG P170 was chosen just because it is a popular budget SDCs from one of the major brands. It is probably manufactured by Takstar because of the striking similarities between the P170 PCBA and the Takstar CM-63 PCBA.
MXL 603S and MXL 991: these are popular microphones among modders, so I decided to add these to the list as well. The 603S is probably popular because of the KM84-style capsule. At the time of writing, I had only acquired the 991, which may or may not have a different capsule compared to the 603S. As far as I know, the Head Amp circuits are identical.
Though the capsule design might be derived from the KM84, it sure does not sound like that at all. But several aftermarket capsules will fit on this body, e.g. from 3U Audio, Microphone-parts.com, and Micandmod.com. These are a major improvement. These capsulesdifficulty will also fit on the Takstar and Alctron microphones discussed further down. The MXL 603 mic body is generally considered of inferior quality compared to the Takstars and Alctron SDCs. The threads have burrs, and capsules screw on with difficulty. But maybe I’ll design PCBAs for these microphones someday if there’s demand for them.
Behringer B-5 and C-2: These are very popular budget SDCs, so from this point of view, they are perfect modding candidates. Actually, the B-5 was the first microphone I modded. However, after comparing it with other SDCs, I lost interest in further developing electronics for the B-5. The cardioid capsule did not sound very good, and I could not find suitable alternatives that would fit on the B-5 body, the smaller PCB limited design freedom (too small for most transformers), and there are no separate pad and low-cut switches. I’ll suffice to describe the circuit and suggest some mods, but I left the idea of doing some serious mods on this microphone.
The C-2 is extremely difficult to take apart, so this one fell off too. Maybe I’ll do something with it later once I have figured out how to get the head amp circuit out. It looks like the nose cone is stuck in the tube. But I like the small form factor for applications where size matters.
Takstar CM-60 and CM-63: these are popular, cheap microphones that are generally considered to be of high quality. The 22mm microphone-parts and 3U Audio SDC capsules will also fit on these microphones, but unfortunately, they are not available in colors matching the Takstars. Transformers will also fit in these tubes, but in the case of the CM-60 you will need to cut off a piece of the XLR pins to get the transformer between the XLR insert and the low-cut switch.
Alctron T02A: Just like the Takstar CM-63, this microphone has a 22mm diameter body and fits the 3U capsules. The thread quality is not quite on the same level as the Takstars, but is good enough. But what makes this microphone especially interesting in combination with the 3U capsules is that the color is almost identical and the back chamber and vent design probably suits the 3U capsules better than those of the CM-63.
Others: Initially, I also had in mind to mod the t.bone SC140 and SC700 and the Rode NT5. However, my focus shifted towards the 22mm diameter SDCs, which fit the excellent 3U capsules.