Knowledgebase
Troubleshooting Intermittent Audio Distortion and/or MIDI Connectivity on Windows
Posted by Ryan Buckley on May 11, 2016 - 4:49 pm

If you are experiencing audio distortion on your Windows computer first check and make sure you are not reaching the CPU limit on the hardware.  If you are you'll see a notification flashing on the LCD of the hardware.  This means you need to remove one or more blocks from the grid to free up some CPU headroom.

If you are not maxing out the CPU continue reading to find out why you may be experiencing issues.

USB Signal Quality
Fractal Audio's Windows driver implements an isochronous transfer mode which uses error checking but no retransmission in case of CRC errors. Electrical noise on USB signals causes CRC errors and thus data loss. This leads to audio signal distortions (clicks). This means that a USB audio device can work only if USB signal quality is good and no CRC errors occur. Most other USB device types (e.g. FLASH drive, printer) are based on bulk transfer mode, which uses automatic retransmission in case of errors. These kind of devices are much more tolerant with respect to USB signal distortion. For this reason, it is possible that a mouse, keyboard, FLASH drive, printer etc. works well on a given USB port using a given cable while an audio device does not work with the same port or cable. Below is a list of possible sources for this kind of problems.

USB cables
Quite often, the USB cable (or its connectors) is the cause for USB signal distortions. Some cables available in the market are not suited for USB 2.0 high-speed communication (480 Mbps). Also the maximum allowed cable length of 5 meters should not be exceeded.

Solution: Try using a different cable. Try a shorter cable (less than 2 meters).
Tip: Stay away from special USB cable offerings optimized for audio, or cables which include additional functionality such as status LEDs.

PCB mounted USB ports
We've found that on some PC main boards (or laptops) signal quality of some USB ports is insufficient for isochronous streaming. The cause could be that on the PCB USB signals are routed close to a switching voltage regulator, for example.

Solution: Try using a different USB port to connect the audio device.

Front panel mounted USB ports

External USB ports (mounted on a front panel or elsewhere in the PC case) are a possible source of USB signal distortion. Quality of cables or connectors used to connect the external USB port with the main board could be insufficient, or internal cables are placed close to the power supply or other sources of electrical noise.

Solution: Try using a USB port that is mounted directly on the main board.

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