QC Mini – Right ear only "thin HF whine" when DSP >30%

Quad Cortex
1

Hi everyone,

I’m experiencing a very specific issue with my QC Mini and wanted to check if this is a known quirk or a unit-specific defect.

The Symptom:

  • When DSP load is low (<20%), the headphone out is dead silent.

  • When loading presets with DSP usage **≥30%**​ (Amp + Cab/Capture), a thin, high-frequency tonal whine​ appears in the RIGHT ear only.

  • It sounds like a “tinnitus” or “digital mosquito” (very thin, pure tone), definitely NOT​ the usual broadband hiss/hash. Left ear remains much blacker.

Troubleshooting Done:

  1. **HP Level:**​ Reducing Headphone Output Level (-3 to -6dB) has zero effect​ on the volume of the whine.

  2. **Bypass:**​ Turning blocks off does nothing; the noise correlates strictly with total DSP load, not specific blocks.

  3. **Grounding:**​ The noise disappears or significantly reduces when OUT 1 is connected to an earthed audio interface/monitor.

Question:

Is this just the nature of the floating power supply design (needing a ground reference), or does the fact that it’s right-ear only​ and immune to HP level adjustment​ suggest a faulty headphone jack or PCB ground issue?

Thanks!