Why are audio crackles a) caused by unplugging USB2MIDI cable, and b) fixed by increasing CPU utilisation?

angusts

New member
Joined
Apr 18, 2020
Posts
3
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:
  1. 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.
  2. 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.
 
One thing to try. Uninstall the Nvidia High Def audio component.

I don't have a clue as to the why, I wish I could help there.

Here's a far out guess: It sounds like an electrical resistance/conductance issue. By plugging in the USB2MIDI cable into any 3.0 socket you are changing or balancing the resistance/conductance, also by changing the CPU utilization could be influencing the voltage thus the resistance/conductance.

@Digerati Am I way off?
 
@xrobwx71 thanks for the suggestion - however uninstalling Nvidia HD Audio made no difference.
@xilolee thanks too for your suggestion - but I'm afraid disabling EIST in BIOS also made no difference.
In both cases I continue to get crackles all the time when playing any sort of sound while the USB2MIDI cable is not plugged into a USB 3.0 socket.

Note that I am quite happy to keep my USB2MIDI cable plugged in - I still occasionally use the synth. I am more interested in understanding why the crackles occur when it is not plugged in, but now that I have this workaround it's not a big issue and I wouldn't want you guys to spend a lot of time on it.

Many thanks.
 

Has Sysnative Forums helped you? Please consider donating to help us support the site!

Back
Top