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Theoretically Similar Mics
side-address large-diaphragm dual-diaphragm tube multipattern transformer-coupled pressure-gradient ef86 m7 pvc
Docs and Reviews
- UM 92.1 S Product Desc
- Klaus Heyne on the M7 Capsule
- UM 92.1 S Brochure
- Oliver Archut’s EMI mod
- EQ Magazine, 2003-09
- UM92.1 Mod Ideas
- Tape Op Review (issue #36)
Related Microphones
Microtech Gefell UM 92.1 S
Street: $3,999 / MSRP: €2,580 Multi-Pattern Condenser Tube Microphone
Description
The UM92.1S is a large-diaphragm, multipattern tube microphone with Gefell’s trademark PVC-diaphragm M7 capsule.
The M7 capsule is a center-terminated, dual-diaphragm design, and supports three polar patterns. A switch on the power supply allows selection of Cardioid, Figure-of-8, or Omnidirectional patterns.
The amplifier circuit is similar to some of Gefell’s historical models, the CMV 563 and UM 57, but has been updated with modern components. The tube is an EF 86 pentode, reportedly of Russian origin, wired in triode configuration.
The “.1” Gefell mics, including the M92.1S and UM92.1S, include RF/EM protection circuits required for CE compliance. Although US restrictions on electromagnetic radiation are less strict, Gefell does not currently provide US-only circuits.
According to Oliver Archut of TAB-Funkenwerk, these EMI protection circuits “choke” the sound and introduce phase shift. He has provided instructions for removing the EM/RF circuitry of the UM92.1S. See also this clarification.
We’ve archived Mr. Archut’s schematic here:
Barry Hufker
Using Oliver’s suggested modifications, I changed my stock UM92.1S by: clipping the 1.5k resistor and sending the cathode wire to ground; installing a Telefunken EF86 tube with hilumin shield; installing the same x-former that is used in the UM75.
The difference in sound quality is amazing! I am now finally satisfied with the sound I get from this microphone.
Disclaimer: proceed at your own risk! We take no responsible for fried microphones or fingertips.
The mic ships in a metal suitcase and includes a dedicated power supply (p/n UN 920.1), power cable (p/n C 92.1), elastic suspension mount (p/n EA 92), and gray foam windscreen (p/n W 92).
The mic is available in three finishes:
- satin nickel (p/n 211138)
- matte black (p/n 211139)
- 24K gold anniversary edition
Note that the frequency-response graphs on the MTG website for the UM 92.1 S (and M 92.1 S) are identical to those of the UM75, UMT70S, and MT71S, despite the wild variation in topologies, circuitry, and headbasket design among those microphones. The graphs linked below are samples from an individual UM 92.1 S, and are therefore much more predictive of this mic’s performance.
The Microtech Gefell UM 92.1 S is also known as: UM92.1S, UM92.1.
Specifications
| Frequency Response - Omnidirectional |
|---|
 |
| Frequency Response - Cardioid |
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| Frequency Response - Bidirectional |
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| Pickup Patterns | Pads & Filters |
|---|---|
|
Omnidirectional
(15 mV/Pa; 40 - 18,000 Hz) Cardioid (15 mV/Pa; 40 - 18,000 Hz) Bidirectional (15 mV/Pa; 40 - 18,000 Hz) |
|
| Capsule Dimensions | Impedance | SPL/Noise |
|---|---|---|
| Diameter n/a |
200 Ohms (Low) | Max SPL: 120 dB Self-noise: 17.0 dB(A) |
| Weight | Length | Max Diameter | Interface(s) |
|---|---|---|---|
| 430g (15.17oz) | 197mm (7.76'') | 42mm (1.65'') |
|
| Power Specifications |
|---|
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