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SO.104 Ultrasonic Omni Microphone

Regular price $79.99

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Same exceptional sound as the SO.4 microphone in an all new universal housing. Housed in a 20mm die cast zinc enclosure with a male XLR termination, the SO.104 is compatible with the typical industry standard XLR cable.The SO.104 Ultrasonic Microphone is currently the only Primo EM258 based microphone available in a standard 20mm housing!

The SO.104 is an ultrasonic omni microphone with a natural and extended frequency range. These highly versatile and sensitive mini pencil microphones are great for capturing soundscapes, spatial depth, sound decay as well as the most intricate details and micro nuances. Utilizing the Primo EM258 capsule, the microphone has excellent ultrasonic frequency response and can capture audio well into the ultrasonic range (up to 70k!). Because the SO.104 is omnidirectional, its pickup response is similar to that of the human ear. The EM258 capsule is a favorite among field recordists, sound designers, location sound, artists working with sound, and especially those seeking to record in the ultrasonic range.  

The SO.104 capsule enclosure is fabricated in-house and the SO.104 Microphone assembled by hand in NYC.


What's Included

(1) SO.104 Ultrasonic Microphone 

*x2 above quantity amounts when ordering a matched stereo pair. 

*x4 above quantity amounts when ordering a matched quad set. 


- Exceptional low self noise

- Highly detailed 

- Wide dynamic range and frequency response for accurate sound reproduction across the audio spectrum

- Excellent ultrasonic frequency response that extends well above 20kHz (up to about 70k)

-Balanced, transformerless output for increased immunity to noise over long cable runs

- Universal form factor. 20mm diameter is compatible with many housings and accessories

- Industry Standard High Quality Components and Parts used. Neutrik Gold Pin Connector

- Fabricated in house by hand in NYC.



Capsule | Primo EM258

Polar Pattern | Omnidirectional

Frequency Response | 20 Hz - 70 kHz

Signal to Noise Ratio | 74dB 

Self Noise | 20dBA

Maximum Input SPL | 115dB

Dynamic Range | 95dB

Sensitivity | -32dB (+/- 3.0dB @ 1kHz) Stereo Pairs are matched within 0.3dB @ 1kHz

Operating Voltage | 48V Phantom Power (IEC61938 Standard)

Enclosure | Zinc Diecast Metal with Black Chromium Plating & Black PLA Plastic

Physical Dimensions  | 52mm Length x 20mm Diameter

Polarity | Positive pressure on the diaphragm produces positive voltage on XLR Pin 2

Operating Temperature Range | -20°C ~ +60°C 

Storage Temperature Range | -40°C ~ +85°C

Connection | Three-pin industry standard XLR male connector, Gold Plated


SO.104 Ultrasonic Microphone Product Manual PDF


Frequency Response

20 Hz - 70 kHz (testing data only goes up to 20 kHz)

Audio Recordings


*all recordings made with the SO.4/SO.104 plugged into a Sound Devices Mix Pre-6 II. The recordings contain no post-processing

*any subsequent modifications to the information above will be recorded on the SO.104 Microphone Change Log in the Sonorous Objects Resource Wiki.

Be sure to check out our resource wiki for additional information, contents and downloads. 

Sonorous Objects Resource Wiki