Affordable Ultrasonic Mic? Sonorous Objects SO.104 Review with Audio Samples

Introduction

In my previous post on ultrasonic microphones, I mentioned ordering a stereo pair of the Sonorous Objects SO.104 after reviewing its promising specifications. Now, after some hands-on testing, I’m sharing my insights into how these microphones perform in real-world scenarios. While this review isn’t a comprehensive teardown with intricate measurement data, it offers a practical look at how the SO.104 performs in typical use cases. With example recordings and real-world observations, I’ll explore whether this mic delivers on its promise as an affordable ultrasonic option for field recording and sound design.

First Impressions of the Sonorous Objects SO.104

Unboxing Experience

The Sonorous Objects SO.104 arrived in simple, no-frills packaging: a small cardboard box with each item securely bubble-wrapped and placed in individual plastic bags. A slip of paper included the microphones’ sequential serial numbers, suggesting they are paired by production order to reduce costs. While this approach can work well due to consistent materials and assembly, it’s worth noting that no two microphones are ever perfectly identical. For critical applications like stereo recording of orchestras or drum overheads, even minimal differences can affect the stereo image. However, at this price point, I wouldn’t expect the level of quality assurance seen in high-end or boutique microphones.

Build Quality

The SO.104 features a sturdy (3D-printed?) housing that encases the Primo EM258 capsule, mounted on a high-quality Neutrik XLR connector. This capsule is known for its wide frequency response (20 Hz to 70 kHz), making it ideal for capturing both audible and ultrasonic frequencies. Key specifications include:

Sensitivity: -32 dB
Self-noise: 20 dBA
Signal-to-noise ratio: 74 dB
Maximum SPL: 115 dB

This combination allows the SO.104 to capture intricate audio details, whether it’s subtle environmental sounds or audio that will be pitch-shifted. The low noise floor further enhances its usability for field recording and sound design.

Design and Aesthetics

Compact and lightweight, the SO.104 is easy to integrate into most setups with its standard XLR connector. However, the foam windscreens from the SO.100 series require mic clips to clamp low on the mic body, near the connector. Aesthetically, the microphones feel more like prototypes or DIY builds, with a somewhat unfinished look—not a dealbreaker, but worth noting for those who value polished design.

Setup and Accessories

The SO.104’s compact design ensures easy setup in both studio and field environments. While Sonorous Objects offers some accessories, I needed to source a stereo bar and weatherproof hard case elsewhere. This might be a minor inconvenience for those looking for a complete kit. Additionally, the included foam windscreens didn’t fit snugly, so I wouldn’t recommend them for outdoor use.

Performance Evaluation

Sound Quality: The Sonorous Objects SO.104 offers a natural sound profile typical of small-diaphragm condenser (SDC) omnidirectional microphones. The mics handle dynamic range well, with minimal distortion or clipping, even at high sound pressure levels (SPL). Thanks to the low self-noise of the Primo EM258 capsule, recordings maintain clarity, capturing intricate details like subtle environmental sounds. If you’re seeking an affordable mic for ultrasonic recording, the SO.104 holds its own in capturing a broad frequency range.

Polar Patterns and Sensitivity: As omnidirectional mics, the SO.104 performs admirably across a wide sound field, with good off-axis response in the audible range. In typical use cases, such as recording ambient soundscapes, the mics deliver a balanced stereo image. Notably, when recordings are slowed to analyze ultrasonic content, the microphones reveal natural tonal shifts and nuanced textures, showcasing their ability to capture ultrasonic frequencies effectively.

Overall Observations

The SO.104 offers a flat, natural response across the audible range, consistent with what you’d expect from SDC omnis. Though not laboratory-grade in precision, the SO.104’s sensitivity and broad frequency capture make it a valuable tool for field recording for sound designers, especially when capturing sounds for extreme downward pitch-shifting.

Microphone Data

Comparison with SE8 Matched Cardioid Pair

In my previous setup, I relied on a matched cardioid pair of SE8 for capturing stereo recordings, which are well-regarded for their flat, natural sound and excellent performance in a variety of recording scenarios. The SE8 microphones are known for their precise off-axis rejection due to their cardioid polar pattern, which is ideal for capturing focused sound sources while minimizing unwanted noise from the surroundings. Their frequency response is fairly neutral across the audible range, with a slight high-frequency boost, delivering a transparent, uncolored sound ideal for critical recordings.

SE8 Matched Cardioid Pair Specs:
Polar Pattern: Cardioid
Frequency Response: 20 Hz - 20 kHz
Sensitivity: -35 dB
Self-Noise: 16 dBA
Max SPL: 136 dB
Condenser Membrane Size: 6 mm

The SE8 mics are generally considered versatile and flat in their performance, making them a reliable choice for a wide range of recording tasks, from vocals to ambient recordings. The cardioid pattern isolates sound effectively, offering great detail in the center while rejecting off-axis sounds. In my testing, I was surprised to see these mics are capable of recording detail up to around 30kHz.

How the SO.104 Specs Compare to the SE8

The Sonorous Objects SO.104, on the other hand, brings a new dimension to the table, specifically targeting those interested in ultrasonic frequencies. While the SE8 is a more conventional choice for general-purpose recording, the SO.104 excels in capturing both audible and ultrasonic content, making it a unique tool for field recording and sound design.

Sonorous Objects SO.104 Specs:
Polar Pattern: Omnidirectional
Frequency Response: 20 Hz - 70 kHz
Sensitivity: -32 dB
Self-Noise: 20 dBA
Max SPL: 115 dB
Condenser Membrane Size: 5.8 mm

Compared to the SE8, the SO.104 offers a wider frequency range, extending into the ultrasonic spectrum (up to 70 kHz). This makes the SO.104 a great choice for capturing fine details in both the audible and ultrasonic ranges that the SE8 cannot. However, the SO.104 sacrifices some of the SE8’s isolation benefits, as the SO.104 features an omnidirectional pattern, which can pick up more ambient noise and is ideal for capturing a broader soundscape.

It is worth noting that omnidirectional microphones sound more natural than cardioids because they capture sound from all directions, similar to how human ears hear, and don’t exhibit the proximity effect caused as a result of the way cardioid microphones focus on sound from the front- at lower frequencies, longer (lower frequency) wavelengths of sound become less directional. As a result, the rejection of low-frequency sounds from the sides and rear is less effective, which contributes to the proximity effect of cardioid microphones.

The SO.104’s sensitivity is slightly lower at -32 dB, meaning it’s less sensitive than the SE8 (-35 dB), but this doesn’t impact its ability to capture nuanced sounds, especially in the ultrasonic range. Additionally, while the SO.104 has a larger condenser membrane size (5.8 mm vs. 6 mm for the SE8), the difference is minor, though it may affect how each mic responds to transients and subtle textures. In my testing, I was surprised to see these mics are capable of recording detail up to and possibly exceeding 96kHz.

Overall, the SO.104 offers a unique feature set with its ability to capture ultrasonic frequencies, making it an exciting choice for those seeking to explore the high (frequency) end of the spectrum on a budget.

Real-World Examples and Data

To better demonstrate the SO.104’s ultrasonic capabilities, I’ve included slowed-down audio recordings in various contexts. These environmental and foley recordings show how ultrasonic details emerge when the mic captures frequencies above the audible range for typical sound design use cases. When slowed, even the tiniest nuances become apparent, further emphasizing the mic’s ability to reveal hidden layers of sound. When slowed down significantly- two octaves or more- recordings made with mics that do not have a high frequency extension into the ultrasonic range begin to sound muffled and dull.

Graphs and data collected from these examples will be shared below, where you'll see how the frequency response translates to real-world recordings.

Screenshot of the foley session comparing the SO.104 (top pair) and SE8 (bottom pair) reveals the difference in the two mics ultrasonic responses. While the SE8 perform admirably, they simply do not have the high frequency response required for extreme pitch shifting.

Example Recordings

SO.104 Recordings (Before)

SO.104 voice recordings before down pitching showing lots of ultrasonic content above 20kHz

SO.104 Recordings (After Down-pitching)

SO.104 voice recordings after down pitching 2 octaves showing lots of detail remaining up to 20kHz, resulting in a convincing pitch shift.

SE8 Recordings (Before)

SE8 Recordings (After Down-pitching)

SE8 voice recordings after down pitching two octaves are missing detail in the upper frequencies approaching 20kHz, resulting in a muffled and dull pitch shift.

Conclusion and Final Thoughts

The Sonorous Objects SO.104 proves to be a capable and affordable ultrasonic microphone, offering quality performance at its price point. While it may not compete with high-end microphones in terms of build quality or advanced quality assurance testing, the SO.104 delivers solid results for both field recording and sound design. Its compact design, low self-noise, and wide frequency response make it an excellent option for capturing subtle environmental sounds and ultrasonic frequencies.

For users with a limited microphone budget, the SO.104 is a valuable addition to any mic locker, especially when working with ambient recordings or sound effects that require detailed capture of high-frequency audio. It’s an ideal choice for those looking to explore ultrasonic recording without breaking the bank.

While the ill-fitting SO.100 series foam windscreens may not be the best choice for outdoor use and additional accessories like a stereo bar and weatherproof hard case need to be sourced separately, the Sonorous Objects SO.104 provides great value for its price. Whether you’re a professional sound designer or an enthusiast, this mic is a unique tool that delivers performance where it counts.

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