If you’ve ever chased a studio hum for hours—only to find that everything was wired “by the book”—you’re not alone.
In the 4th episode of Legend Channel, Japanese studio systems veteran Yasuo Kita (Studio Equipment) shares why some noise problems only show up in real rooms, with real gear—and why “grounding” is the most misunderstood word in audio.
Safety note: This article discusses concepts and real-world anecdotes. Any electrical work should be handled by a qualified technician or licensed electrician.
Key Takeaways (Quick scan)
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“Follow the manual” can still create noise—because manuals assume ideal conditions.
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A thick safety-earth wire can unintentionally become part of an audio loop, acting like a giant antenna.
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People often mix up safety earth (shock protection) with audio grounding (noise control)—they’re not the same.
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Vintage gear can “tingle” due to aging capacitors; removing parts may reduce shock risk but increase noise.
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Practical troubleshooting is often about changing how grounds are referenced, not “adding more ground.”
When “Do What the Manual Says” Still Fails
Kita describes a situation many engineers recognize:
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The studio follows each manufacturer’s wiring instructions.
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The noise still won’t disappear.
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Each vendor says, “We followed the spec—this isn’t our problem.”
That’s when real-world problem solving starts—because the system isn’t just one device. It’s a network: console, multitrack recorder, outboard gear, power distribution, building wiring, HVAC, and more.
The Counterintuitive Moment: “The Ground Wire Was Causing the Problem”
One story hits hard:
A stubborn noise problem changed dramatically when a thick earth/ground wire was disconnected (or the grounding approach was changed).
Kita explains the idea in plain terms:
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Audio should travel through signal paths.
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But if grounding is implemented poorly, current can split and travel through an unintended path.
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That creates a large loop—effectively a big loop antenna that picks up (and radiates) noise.
This is why some “perfectly correct” wiring becomes noisy once it meets the real world.
The Biggest Confusion: Safety Earth vs Audio Ground
A core point Kita repeats: people combine two different goals under one word:
1) Safety earth (shock protection)
This is about preventing dangerous touch voltages. It’s not optional.
2) Audio grounding (noise control)
This is about controlling reference points and return paths so your system stays quiet.
The problem is that many devices provide only a safety-earth terminal, and people assume it’s the same as “audio ground.” Connecting everything together can create loops, especially when power and signal share unintended return routes.
HVAC & Inverter Noise: Why the “Outdoor Unit” Matters
In the conversation, the team suspects an air conditioner outdoor unit (inverter-related noise) influencing the system. The fix wasn’t “magic”—it was tracing how the noise entered the studio and changing the grounding reference / path so the interference stopped coupling into audio.
This is a great reminder: noise isn’t always “inside your audio gear.” Sometimes it’s a building/system interaction.
A Practical Troubleshooting Mindset (No “One Weird Trick”)
If your studio hum won’t go away:
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Don’t assume “more grounding” always helps.
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Identify whether you’re dealing with:
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ground loop / return path issue
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external interference (HVAC/inverter)
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faulty or aging components
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Change one thing at a time, listen, measure, and document.
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When you’re stuck, bring in someone who’s solved dozens of these in real rooms—not just on paper.
Kita’s best point might be this:
The principles matter—but you often have to “hear it and touch it” to solve it.
About the Guest - Yasuo Kita
Yasuo Kita is the Representative Director of Studio Equipment Co., Ltd. (Tokyo), a specialist firm that designs, builds, and maintains audio systems for broadcast studios, post-production (MA) facilities, and music recording studios. Founded in 1977 and incorporated in 1986, the company is trusted for end-to-end studio infrastructure—from system design and installation to equipment manufacturing, maintenance, and professional audio imports. With decades of hands-on field experience, Kita is widely known in Japan’s studio community for solving complex real-world issues like power noise and grounding that don’t always behave “by the manual.”