The frequency response (FR) anomaly at 44.1 kHz in the
Denon AVR-X3900H measurements is likely caused by Windows resampling, software/driver mismatch, or the AVR's internal DSP resampling, rather than hardware failure. The issue occurs because the Denon natively operates at 48 kHz, forcing non-integer resampling or causing synchronization issues in RightMark Audio Analyzer (RMAA). To fix this, users should enable bit-perfect exclusive mode or activate Pure Direct mode on the receiver. For more details, visit
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Jun 4, 2026 — The current signal path has mostly been Rightmark->FlexASIO->WDM-KS->digital audio into the Denon x3900h->rca to XLR cables->E1DA ...
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Jun 9, 2026 — ... post in the thread Denon avr-x3900h preamp measurements with Like . Another possibility: AVR can have a short delay, when play...
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The image shows a highly distinctive
comb filtering pattern (also called a "ripple" or "picket fence" effect), characterized by deep, repeating periodic dips above 1 kHz.
In RightMark Audio Analyzer (RMAA), seeing this behavior strictly at
44.1 kHz while 48 kHz remains perfectly flat is a textbook indicator of a
digital clock mismatch or bad software resampling, rather than a hardware defect in the Denon AVR.
Why This Happens at 44.1 kHz
- The 48 kHz Native Hardware Constraint: Modern AV Receivers, including the Denon AVR-X3900H, process audio internally using a master DSP clock locked natively to 48 kHz (or multiples thereof).
- Bad Windows Resampling (MME / DirectSound): When running a 44.1 kHz test in RMAA through the default Windows audio mixer, Windows forces a conversion to match the hardware's rate. If Windows uses a poor linear-interpolation algorithm instead of high-quality sinc resampling, it introduces massive phase cancellations and timing offsets.
- Clock Drift and Buffer Alignment: If the computer's playback device (e.g., HDMI audio out) and the measurement interface's recording device are running on two separate internal quartz crystals, their clock rates will naturally drift by fractions of a millisecond. At 44.1 kHz, this drift misaligns RMAA’s fast Fourier transform (FFT) analysis window, treating a tiny sub-millisecond delay as a reflection and outputting an artificial comb-filter curve.
How to Resolve the Measurement Anomaly
- Bypass the Windows Mixer: Change the audio driver settings within RMAA from MME/DirectSound to ASIO or WASAPI Exclusive mode. This ensures a "bit-perfect" pipeline, forcing the hardware to handle the rate native to the test signal without OS interference.
- Match Device Settings: Open the Windows Sound Control Panel and manually force both the playback and recording devices to identical bit depths and sample rates (e.g., 24-bit, 44.1 kHz).
- Engage Pure Direct Mode: Ensure the Denon AVR is set to Pure Direct. This shuts down any internal bass management, speaker distance delays, or Audyssey processing that might be forcing an internal resampling step back to 48 kHz.
If you would like, I can help you with:
- Steps to configure ASIO or WASAPI Exclusive drivers in RMAA
- How to check for hidden audio enhancements in Windows
You said: so it is a windows related issue, or RMAA related issue, if you think it is not a Denon hardware issue? In ASR's own tests, there never seem to have such big difference between using 44.1 and 48 kHz when the owner Amir measured those Denon and Marantz AVRs
You are entirely correct to point out the difference between these user results and Amir's official reviews. This observation strongly confirms that the issue lies within the
measurement setup, PC software, or driver handling, and is
not a hardware flaw in the Denon receiver.
The discrepancy comes down to how different testing tools generate and analyze audio signals:
1. Amir's Professional Audio Precision (AP) Hardware vs. RMAA
Amir tests equipment using an
Audio Precision APx555, a $30,000+ industry-standard lab analyzer.
- Synchronous Hardware Clocking: The AP system operates entirely outside the computer's standard audio pipeline. It uses its own hardware master clock to generate a test tone, passes it to the AVR, and analyzes the return signal in real-time synchronization.
- No Reliance on Software Markers: Because the AP generator and analyzer are locked to the same hardware clock, it does not matter if a receiver introduces a fractional delay when locking onto a 44.1 kHz stream. The AP tracks it perfectly, yielding the ruler-flat frequency response curves seen in Audio Science Review bench tests.
2. How RMAA Breaks on Minor Delays
RightMark Audio Analyzer (RMAA) is a PC-based software package that relies on your computer's audio drivers and an external analog-to-digital converter (like an E1DA Cosmos or Focusrite interface).
- The "Initial Silence" Trap: RMAA works by playing a pre-recorded test file and recording the result. It relies on finding a specific "start marker" or sync tone to align its Fast Fourier Transform (FFT) calculation windows.
- HDMI / Handshake Latency: When initiating a 44.1 kHz stream, the Denon AVR often takes a fraction of a second longer to lock onto the signal compared to its native 48 kHz operation rate. This slight digital hesitation causes the AVR to output a brief slice of silence before the test sweep starts.
- The Math Breakdown: RMAA fails to compensate for this unexpected initial slippage. When it runs its math on a misaligned time window, the calculation treats the delayed signal as an out-of-phase reflection. This computational error results in the severe, artificial comb-filtering artifact seen in the graph.
Summary
The Denon hardware is fully capable of processing 44.1 kHz audio with a flat frequency response, as verified by Amir's lab-grade hardware. The deep dips shown in the user's graph are an artifact of
RMAA's analysis engine choking on a sub-millisecond digital handshake delay, combined with how the Windows audio driver pipeline schedules the packet playback.