Gradually increasing microphone monitoring latency with FIFINE AM8 (Windows 11 25H2)

C

Clegy

New Member
Hi everyone,

I've been troubleshooting a very unusual microphone monitoring issue for several days and have exhausted most of the common troubleshooting steps. I'm not sure whether this is an OBS issue, a Windows issue, or a USB audio compatibility issue, but I'm hoping someone recognizes the symptoms.

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System

  • OBS Studio 32.1.2
  • Also tested OBS 32.2 Beta
  • Also tested OBS 30.2.2
  • Windows 11 Version 25H2 (Build 26200.8737)
  • Acer Aspire 7 A715-76G
  • Intel Core i5-12450H
  • NVIDIA RTX 2050 Laptop GPU
  • FIFINE AM8 (USB-C to USB-A)
​
Problem

My USB microphone monitoring gradually becomes delayed over time.

It starts with essentially zero latency.

After approximately 5–10 minutes, the monitored microphone becomes increasingly delayed. The delay continues growing and can eventually exceed one second.

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The strange part

If I disable microphone monitoring and immediately enable it again, the delay instantly disappears.

However, after a few minutes it starts accumulating again.

This behavior is repeatable.

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Important observations

  • OBS recordings appear normal.
  • The issue affects live monitoring.
  • Windows Sound Recorder records the microphone normally.
  • The built-in laptop microphone does not exhibit this issue.
  • The issue occurs when monitoring directly to speakers.
  • The issue also occurs when monitoring through VB-Cable.
  • The delay continues to accumulate even when Discord is closed.
  • The delay also appears in Discord's speaking indicator when using the monitored microphone.
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Observation that seems important

I also monitor a VST piano through OBS.

When I press a piano key and speak at exactly the same time:

  • the piano is heard immediately
  • my voice arrives increasingly late
The VST remains synchronized while only the microphone monitoring drifts.

Because of this, it appears the monitoring output itself is not drifting. Only the live microphone path is.

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Troubleshooting already performed

  • Tested OBS 30.2.2
  • Tested OBS 32.1.2
  • Tested OBS 32.2 Beta
  • Different USB ports
  • USB hub
  • Disabled Exclusive Mode
  • Disabled Device Timestamps
  • Confirmed 48 kHz in Windows and OBS
  • Removed and reinstalled the microphone device
  • Removed hidden audio devices
  • Tested with Discord closed
  • Tested with browser closed
  • Tested with Spotify closed
  • Tested with Xbox Game Bar disabled
  • Tested monitoring directly to speakers
  • Tested monitoring through VB-Cable
  • Windows in-place repair installation (keeping files/apps)
  • Laptop microphone works normally
One thing I have not yet successfully tested is a true portable-mode OBS installation.

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OBS Log

 
Windows Control Panel reports the microphone is configured for 2-channel, 16-bit, 48000 Hz, but the OBS log initializes the microphone as:

<span>WASAI: Device 'Microphone (fifine Microphone)' [44100 Hz] initialized</span>

I don't know if this is expected behavior, but it stood out while reviewing the log.
 
I allowed OBS to run for approximately 25 minutes until the monitoring latency had clearly accumulated. I then uploaded the active log. The log contains no timestamp errors, buffer growth messages, WASAPI warnings, or synchronization messages after initialization, even though the delay was clearly audible by that point.

 
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