airbladder, I've used Neumann USA's repair service numerous times for both large- and small-diaphragm microphones, including U 89s, with good results. I recommend them for any current-model Neumann microphone, as well as older models for which parts are still generally available (e.g. KM 84, U 67).
But I don't believe there's any such thing as having two Neumann microphones "pair matched" after the fact, short of ordering two new factory-matched capsules and having them installed. This would probably cost $1500 or more, assuming that Neumann would do it, and I doubt that it is worth the cost unless you do a lot of coincident or near-coincident recording and already need to replace both of your capsules for other reasons.
During repair work it isn't necessary to check all permutations of the analog switch settings; if you simply check each switch, the permutations take care of themselves. The three switches don't interact directly.
Generally the tech at Neumann USA performs a set of "go/no-go" diagnostic checks on any microphone's capsule. Neumann doesn't test the response precisely in the U.S.; their measurement test chambers are in Germany, so the U.S. branch would have to send every microphone back there, which of course would take several extra weeks and create enormous extra expense for all the shipping and handling.
One place in the U.S. which does expert repairs on Neumann microphones and has an acoustical test chamber is Stephen Paul Audio in California. But they don't make frequency response measurements unless there is specific cause to do so, and I believe there is an extra fee for that service. It's not quite like popping bread into a toaster.
--best regards
Topic: Neumann Microphone Repair (Read 4364 times)