This is a strange problem, for which I've found 2 work-arounds, but I'd be interested if anyone can explain WHY it's happening, and if there's a better fix.
System:
CPU: Intel i7-4390K (6 cores, 12 threads, 3.4GHz)
RAM: 32 GB
Graphics card: Nvidia GeForce GTX 660
Internal SSD: 2 x 256 GB
Internal HDD: 1 x 2TB, 1 x 3TB
External HDD: 1 x 500GB
Speaker system: Logitech Z4
OS: Windows 10 Pro 64-bit, version 1809, build 17763
Background:
I recently bought an ORICO USB 3.0 4-Bay Hard Drive Docking Station as a quick way of attaching a couple of 1GB internal HDDs (harvested from an old Windows XP PC) to use as backup drives. I freed up a USB 3.0 socket to use for the Orico by unplugging my USB2MIDI cable (which connects an old Roland D50 synth) and plugging the USB2MIDI into a USB 2.0 socket.
Problem:
The next time I listened to music on the PC (about a week later) the audio was horribly and persistently crackly.
Fixes which failed:
- Unplug speaker system from PC and plug into phone - no crackles, speakers fine.
- Ensure Realtek High definition Audio driver is up to date.
- Ensure all sound effects are disabled.
- Drop sound quality from 24 bit, 96000 Hz to 16 bit, 44100 Hz.
- Turn off Exclusive Mode ("Allow applications to take exclusive control of this device").
- Power management: change minimum processor state from 5% to 100%.
- Download & run LantencyMon - says "system OK for handling real-time audio".
- Install latest 'Game ready driver' from Nvidia for GTX 660 (version 445.87).
As the above fixes had no effect I reversed them all apart from the Nvidia driver update.
Fixes which worked:
- INCREASE CPU utilisation:
I noticed the crackles reduced when I was running a virus scan and subsequently determined that the amount of crackling was dependent on CPU Utilisation (as displayed by Task Manager). I used CPUSTRES64 (from Sysinternals) to load the CPU and verify this as follows:
- Below 5% CPU utilisation - crackles were really bad.
- Between 5% and about 15% utilisation - crackles reduced as utilisation increased.
- Above 15% utilisation - crackles were completely gone.
- Processor speed was irrelevant:
- using power management to alter mimimum CPU speed between 1.5 GHz and 3.4 GHz had no effect.
- crackles were dependant only on CPU utilisation.
- Plug USB2MIDI cable into any USB 3.0 socket:
- USB2MIDI cable plugged into any USB 3.0 socket - NO CRACKLES
- USB2MIDI cable plugged into USB 2.0 socket - crackles
- USB2MIDI cable unplugged - crackles
Summary and question:
So the crackles are caused by UNPLUGGING my USB2MIDI cable from it's USB 3.0 socket.
The crackles can be eliminated by driving the CPU utilisation ABOVE about 15%, or by plugging the USB2MIDI cable back into any USB 3.0 socket.
This seems counter-intuitive. Can anyone offer any explanation, and/or suggest a fix that would work without either a) requiring thw USB2MIDI cable to be plugged in, or b) driving CPU utilisation above 15% ?
Many thanks.
