Common name: Neumann TLM 50
Production Status: Discontinued / Vintage
The TLM 50 is the first studio microphone designed by Georg Neumann GmbH as a successor of the M 50 and M 250, both discontinued in 1971. The M50 was manufactured from 1990 until 2014 and belongs to the “fet 100″ series. This microphone employs, like its predecessors, a pressure diaphragm flush mounted in a diffraction sphere to achieve some particular performances. For physical reasons the flush mounted diaphragm exhibits particular behavior, depending on the diffraction sphere diameter. The transducer has a very smooth response up to the frequency in which the wave length becomes comparable with the sphere diameter, then, for higher frequencies with smaller wave lengths, the frequency response is boosted. For a 40 mm sphere this limit is around 1 kHz, then the frequency response rises gradually with an overall +6 dB boost in the 8000-16000 Hz range. The polar response is at the same omnidirectional for lower frequencies and directional for higher ones. The transducer practically works like a pressure one for low-end and like pressure gradient for higher frequencies. These features make the microphone the perfect choice for high distance environmental orchestra recordings, as high frequencies are more prone to long distance attenuation than low frequencies. The TLM 50 uses the new KK 33 capsule in which a 12 mm (5 um thickness) diaphragm is flush mounted in a plastic 40 mm diameter sphere with some technology improvements. At first the new capsule was designed as an active capsule, with the impedance converter built-in as an hybrid module. This makes the element (transducer – impedance converter) much more resistant to hum noise picked-up through the grille mesh than a conventional one. The transformer-less technology enhances CMRR, RF immunity, self noise performance, transients response and output capability (longer cables can be used without sound degradation). The microphone features a switchable – 10 dB attenuator and a low cut filter. The attenuator works by reducing the polarizing voltage at the capsule from 60 V to 23 V. This design doesn’t extend the dynamic range of the microphone amplifier by changing the amplifier negative feedback as with the”fet 80” series microphones but moves it upward by 10 dB to prevent following equipment overload. Furthermore the reduced polarization voltage has the effect of changing the acoustic impedance behind the diaphragm, resulting in a small high frequency response change. The low-cut filter is designed to work for frequencies under 100 Hz. In the “LIN” position the filter is not completely excluded but shifted to 16 Hz to avoid subsonic overload as the transducer and the microphone amp have a virtually unlimited low frequency response. The sensitivity is quite high at 20 mV/Pa, 9 dB higher than the M 50. In 2001 the microphone adopted the new titanium diaphragm capsule (KK 33 Ti) designed for the M 150 Tube microphone. The TLM 50 is only available in dark matt finish. Small diaphragm pressure microphones with sphere flush mounted transducer are all engineered for orchestra recording. Although often used in “Decca Tree” configuration, with or without out-triggers microphones, they can also be used also in A-B center-fill technique, as M50’s were used in some Rca Victor’s Living Stereo productions. The microphone won the TEC award in 1991.