I have a lavalier mic, Sanken COS-11x, that comes with power adapter which plugs into an XLR input with phantom power. A good solution for using the lav into a field recorder. However, I want to use the same mic with Sennheiser wireless transmitter. So, I cut the mic's cable near the XLR power adapter and soldered male-female 3.5mm (1/8"?) RTS connectors. However, these connectors are far from being reliable. At times, either there is no connection (and hence, no sound), or terrible noise when the connectors are turned, one against the other, in order to make contact between the male and female.
So, I'm looking for alternative for on-cable connectors.
Either good and reliable 3.5mm RTS connectors (if there are such), or connectors of different type. Reliability and good contacts are paramount. Size matters, the smaller the better, and cost also matters, but is secondary consideration, maybe up to $10 per single connector (I'll need 3 altogether).
What are your recommendations?