This sounds like a ground loop. Try changing your plug configurations for the Tempest and your laptop, i.e. try unplugging your laptop from the wall and see if the problem still exists, and try plugging your Tempest and the computer into the same outlet. You can also try using a surge protector/power conditioner, try powering your audio interface with a wall plug if it is bus powered normally, try plugging your Tempest into a different USB port, use a different or shielded USB cable, or try a USB hub if you haven't already.
If none of the above suggestions work, users have had good results using the following method. You must have an extra USB cable you don't mind modifying:
```
- Using wire strippers and/or wire cutters, Strip away a 10-15mm section of the rubber coating in the middle of the USB cable to expose the braided shielding.
- With the wire cutters, carefully cut the shielding away entirely, exposing the 4 wires surrounded by the shield.
- Make sure the shield is completely disconnected. Verify this by testing for continuity on both metal ends of the cable.
- Cut the black wire, which is connected to pin #4 and represents ground. This creates a "ground-lift".
- Fold the ground wire back and out of the way, then wrap the exposed section of the USB cable with electrical tape. Your ground noise should be gone.
```
If you'd rather not try a DIY fix, some companies also make USB signal isolators. Here are some examples:
**USA:**
[USB signal isolator] **EU:**
[USB signal isolator] You can read more about locating and eliminating ground loops in your system at the following web link (PDF file):
[Understanding & Eliminating Ground Loops]
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