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SO.3 Cardioid Microphone

Regular price $119.99

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The SO.3 is a cardioid microphone with incredibly high sensitivity, a rich full-bodied sound, and a high end characterized by a natural and airy presence. All of this packaged in a small form factor designed to be compatible with all of the Sonorous Objects Standard series accessories. When used in near field scenarios, the SO.3 provides excellent environmental noise rejection allowing you to fully focus on your subject without distraction while hearing every micro nuance and detail presented to you in the process. In further field scenarios, the SO.3 captures beautifully spacious and realistic sound fields.

Our favorite applications for the SO.3 are Sound Design & Effects, Foley, and Instrument & Musical Recording. The SO.3 utilizes Primo’s recommended cardioid capsule, the Primo EM423 capsule, known by recordists and sound designers for its directionality, detail, and its effortlessly natural frequency response.

We’re excited to be able to provide a frequency response graph and response data table that is specific to the unique microphone capsule used in the SO.3

The SO.3 capsule enclosure is fabricated in-house and the SO.3 Microphone assembled by hand in NYC.


What's Included

(1) SO.3 Microphone

(1) SO Standard Microphone Cable XLR or 3.5mm

(1) SO Standard Microphone Clip

(1) SO.3 Standard Attachable Foam Windscreen

Frequency Response Graph that is specific to the unique microphone capsule that you will receive.

Operation Manual

*above quantity amounts will be doubled when ordering a matched stereo pair. 


- Exceptionally low self noise

-Utilizes Primo’s new and improved cardioid capsule, the EM423, delivering an additional 10dB of dynamic range over the EM204 capsule.

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

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

- Fantastic level of detail and clarity on-axis. High level of performance at rejecting rear sounds.

- Excels in studio and controlled environments. Ideal for Sound Design/Effects, Foley, and Instrument Recording. Performs well in the field with high level of wind protection. The SO.3 is sensitive and prone to wind and plosives.

- Can be used individually or as a matched pair. Stereo miking techniques yield spacious and accurate stereo fields.

- Small Form Factor

- Frequency Response Graph and Data unique to the specific capsule used in the mic that you receive. 

- Industry Standard High Quality Components and Parts used. Neutrik Gold Pin Connectors/Amhpenol 3.5mm plug, Mogami Shielded Cable.

- Fabricated in house by hand in NYC.

*SO.3, SO.1, and SO.4 Accessories are interchangeable and cross compatible.


Capsule | Primo EM423

Polar Pattern | Cardioid

Frequency Response 20hz - 20khz. (Spectrograms show extended range)

Signal to Noise Ratio | 76dB 

Self Noise | 16dBA

Maximum Input SPL | 135dB

Dynamic Range | 119dB

Sensitivity | -42dB (+/- 3.0dB @ 1kHz) | Stereo Pairs are matched within 0.3dB @


Operating Voltage | 48v Phantom Power (IEC61938 Standard) with SO XLR Cable option only*. 3.5mm connector option operates on typical Plug In Power

*Included SO XLR cable contains special circuitry to allow microphone to interface with 48v Phantom Power. Third party cables XLR are not supported.

Enclosure | Black PLA Plastic & Nickel Plated Aluminum

Dimensions Unconnected | 45mm Length x 18.7mm Diameter

Dimensions Connected |  83mm Length x 18.7mm Diameter

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

Operating Temperature Range | -10°C ~ +50°C  

Storage Temperature Range | -20°C ~ +70°C

Cable | Shielded, Mogami, 6 ft length terminated with a three-pin industry standard XLR male connector, Gold Plated.* OR Amphenol Mono/Stereo 3.5mm connector

*SO XLR cable contains special circuitry to allow microphone to interface with 48v Phantom Power. Third party cables XLR are not supported.

SO.3 Microphone Product Manual PDF

Frequency Response

Audio Recordings


*all recordings made with the SO.3 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.3 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