MXL 990 Capsule Mod
We swapped out the original SDC capsules for two matched K-47 style capsule we got from microphone-parts.com (their RK-47). These are wired up in Omni mode, and they sound awesome! These two 990s also got the capacitor and headbasket mods (see previous sections).
Below you can see that the original capsule is actually a SDC, surrounded by a brass ring.
Once the capsule has been removed from the plastic mounting ring, the ring can be removed from the post by removing the indicated screw.
You can use the same screw to attach the mount that comes with the RK-47 (or whichever capsule you got) to the original mounting post. Even though you are replacing the small capsule with a larger one, the original post height works well.
Below, we see the new capsule mounted to its mount, and the wires fed down through the holes in the dome.
For this pair of 990s, we opted to hard wire them as Omnis, so the two white wires (to the two diaphragm center terminals) are tied together and attached to the post that feeds the JFET. The blue back plane wire connects to the same pad that the original capsule's back plane connected to. On another 990 project, and a pair of 770s, we added an internal toggle switch to switch between Omni and Cardioid mode. we may come back to these at some point, and add an Omni / Cardioid switch, as it is a pretty easy mod, and really makes these mics pretty versatile.
Here, the modded headbasket has been reinstalled, and you can really see how open it is.
Finally, back together, and in its travel case!
