Case Study: Fixing a Rising Noise Floor on a Focusrite Scarlett

By Paul Andrews, Founder

The Challenge

A voiceover artist building her new home recording studio reached out for help and booked a Live Diagnostic Call. She had invested in industry-standard gear—a Rode NT1-A microphone and a Focusrite Scarlett 2i2 4th Gen audio interface—but was hitting a major roadblock. Her recordings were plagued by an excessive background noise floor. Even worse, the noise wasn’t constant; the loud hissing sound would actually increase dramatically whenever she paused to take a breath or stopped speaking entirely.

The Amazing Audio Solution

We connected via a WhatsApp video call, and I used AnyDesk to view her Mac’s screen while routing her live microphone feed to my studio monitors using the AudioMovers plugin. Hearing the raw audio in real-time was crucial for diagnosing the issue.

• Ruling Out the Environment: First, we eliminated physical causes. She lived in a quiet rural area, and a quick video tour of her vocal booth confirmed there were no humming appliances, air conditioners, or power cables crossing audio lines to cause interference.
• Software vs. Hardware Diagnostics: We made test recordings using both TwistedWave and Audacity to rule out any app-specific glitches. I noticed a distinct visual pattern in the audio waveforms: the noise level visibly swelled up like a wave during the silent gaps between her words.
• Identifying Auto-Gain: This swelling effect is a classic symptom of automatic volume leveling (AGC or Auto-Gain). The system was trying to “help” by turning the volume up when she stopped speaking, which dragged all the microscopic room noise up to maximum volume.
• The Hidden Physical Solution: I opened the Focusrite Control 2 software on her Mac. We checked the Auto Gain, AIR, and SAFE settings. Surprisingly, even after appearing to disable Auto-Gain in the digital software, the rising noise remained. Through deep knowledge of the 4th Gen hardware, I realized the software control was bypassed; she had to press a specific physical button on the front panel of the Scarlett interface itself to truly defeat the auto-gain circuit.

The Result

The moment she pushed the physical button on the interface, the auto-levelling stopped. The swelling hiss completely vanished, leaving her with the crisp, clean, professional noise floor that the Rode NT1-A is famous for. By diagnosing this non-intuitive hardware quirk, we saved her the immense frustration of buying expensive noise-reduction plugins or attempting to return perfectly good equipment.

Client Feedback

The client was relieved to have this elusive technical glitch solved and left this fantastic review:

“Paul helped me diagnose a problem with my interface that honestly, I would have never figured out on my own. It’s clear he is a consummate professional and talented audio engineer, and I definitely recommend his service!”