Neumann microphones are not only a requisite for everyday use, but also a long-term investment, as proven by the microphones sent to us for a first overhaul, some after 40 years of use. In some cases, though, the life expectancy of the microphone has been shortened due to improper handling and care. To ensure optimal microphone maintenance, here are a few cues from our service department:
Protect the microphone from pollution:
The microphone capsule as well as the input circuit are of an extremely high impedance. Pollution with dust, ash, fluff, nicotine, etc. can degrade the insulating properties of the materials.
Especially under damp conditions (due to close mic vocal applications or high climatic humidity) interfering noises can be produced. This can be avoided with the following precautionary measures.
Use the dust cover:
Microphones not in operation should not be left on the floor stand unprotected. With a non-fluffy dust cover the microphone can be protected from dust settling on the capsule. When not in use for a longer spell, the microphone should be stored in a closet at standard climatic conditions. Do not seal the microphone in a plastic bag, in case moisture is trapped inside.
Use a pop screen:
The pop screen not only eliminates the plosive pop noises in vocal recordings. In close-mic vocal applications it also efficiently protects the diaphragm from almost anything, including breath humidity down to food particles.
Do not use overaged wind shields:
Even the foam material of wind shields ages. With very old wind shields, the material decays and becomes brittle. The particles can then settle on the microphone diaphragm. So, please dispose of overaged wind shields.
Function testing:
Modern condenser microphones cannot be harmed by very high sound pressure levels. Still, there is no need for pop-testing to see if a microphone is working and pulled up on the console. Normal speech is good enough, and poptesting can produce sound pressure levels exceeding 140 dB! Especially with some of the older microphone types (M 50, KM 5x, KM 25x, KM 88, SM 2, SM 23, but also TLM 50), the diaphragm consists of an extremely thin metal foil. With these models, the very large excursion produced by pop-testing can lead to the diaphragm touching the back electrode, thus producing a spark discharge damaging the diaphragm.
Do-it-yourself repairs can be expensive:
Do-it-yourself repairs can sometimes be more harmful than beneficial. Especially cleaning soiled capsules does take a skilled hand and quite some experience. Furthermore, the protective lacquer shows the parts of the printed circuit boards where e.g. soldering should be avoided. Other parts may be specifically selected and cannot be replaced by standard components. To avoid unnecessary cost, we recommend sending in defective microphones to our authorised service centers for repairs.
Regular servicing:
As some theatres and broadcasters do on a regular basis, sending in microphones for servicing can help in early recognition of damages. Slight soiling can be removed much easier than some nicotine layer firmly embedded in the diaphragm. Especially with microphones on loan and in dustier / smokier environments regular checking proves beneficial, as the cost is rather small compared to a major overhaul. In any case, should it become necessary, we will do our best to repair even vintage microphones (from 1947 on) with original spare parts. May your microphones last another few decades