Microtech Gefell M990 is a large-diaphragm vacuum tube condenser microphone with a fixed cardioid polar pattern, built around Georg Neumann's original M7 capsule with a PVC membrane — the same capsule technology as the Neumann U47, U48, and M49. The M990 is the only current tube microphone in the Gefell line equipped with the M7 capsule, combining the historically authentic transducer element with a tube amplifier circuit built around an ECC 83 (12AX7). It requires a dedicated external power supply included in the set. Sensitivity is 22 mV/Pa, self-noise is 14 dBA, and maximum SPL is 136 dB. The large conventional cylindrical steel body in dark bronze finish is substantially more massive than the compact UMT 70S carrying the same capsule. Hand-built in Gefell, Germany.
ECC 83 tube and M7 capsule — historical pairing in a modern instrument
The M7 capsule in the M990 uses PVC as the membrane material — the same technology used in the Neumann U47, U48, and M49, and the most demanding of all capsule membrane materials in terms of manufacturing skill. The ECC 83 (12AX7) is a dual triode, a classic tube used in low-noise audio signal circuits, referencing the tradition of studio tube microphones from the 1950s and 1960s. The tube circuit adds the characteristic harmonic saturation and transient compression typical of thermionic devices, imparting depth and warmth to the recorded signal that is unavailable in FET designs. The M990 requires a warm-up period before recording (approximately 3–5 minutes) and is more sensitive to ambient temperature variations than FET microphones — standard characteristics for a tube microphone of this class. The included power supply delivers plate voltage and filament supply; the microphone connects to the power supply via a multi-pin cable, with a standard 3-pin XLR output from the supply to the preamplifier.
Applications and position in the Gefell line
The M990 is intended for engineers and producers who need the tube character combined with the historical authenticity of the M7 capsule — in vocal, instrumental, and acoustic applications demanding maximum depth and presence. The advantage of the M990 over the FET M7 microphones (UMT 70S, MT 71S) is subjective and stylistic: tube compression, subtle harmonic saturation, and the characteristic liveness of a tube microphone. Compared to the M930 (M9 capsule, FET): the M990 adds the depth and warmth of the tube circuit, while the M930 delivers lower self-noise and higher maximum SPL. Primary applications: studio vocals, piano, string instruments, voice-over, brass, and wind sections. The dark bronze body finish matches the historical Gefell aesthetic and coordinates with other Gefell accessories in this color.
KEY FEATURES
- Tube large-diaphragm cardioid condenser microphone with M7 Neumann capsule
- M7 capsule: single-sided gold-sputtered PVC membrane — same technology as U47, U48, M49
- Tube: ECC 83 (12AX7) — classic dual triode for audio signal circuits
- Requires dedicated external power supply (included)
- Sensitivity: 22 mV/Pa
- Self-noise: 14 dBA
- Maximum SPL: 136 dB at THD below 0.5%
- Frequency response: 40 Hz – 18 kHz
- Fixed cardioid polar pattern
- Tube circuit: harmonic saturation and transient compression — depth and warmth unavailable in FET
- Warm-up period required: approximately 3–5 minutes
- Large cylindrical steel body — more massive than UMT 70S / MT 71S
- Finish: dark bronze
- Hand-built and individually measured in Germany
- Included: microphone, dedicated power supply, multi-pin cable, shockmount, wooden case
TECHNICAL SPECIFICATIONS
- Acoustic operating principle: tube condenser
- Polar pattern: cardioid (fixed)
- Capsule: M7, single-sided gold-sputtered PVC membrane
- Tube: ECC 83 (12AX7)
- Frequency response: 40 Hz – 18 kHz
- Sensitivity: 22 mV/Pa (-33 dB re. 1V/Pa)
- Self-noise: 14 dBA (IEC 651)
- Maximum SPL: 136 dB at THD below 0.5%
- Output impedance: 200 ohms
- Recommended load impedance: 1,000 ohms minimum
- Power: dedicated external power supply (included)
- Body dimensions: approximately 185 mm (L) x 55 mm (diameter)
- Weight: approximately 490 g
- Finish: dark bronze (alternative: satin nickel)
- Included: M990 microphone, dedicated power supply, multi-pin cable, EA 92 shockmount, wooden case
