SAFE Audio Interface Protector Kit (Archive)

This product is discontinued. This page is just here for archival purposes.

SAFE (’Scope Analog Front End) protects your audio input so you can confidently test your DIY gear before plugging it into your interface. Experienced builders can also use it to test new circuits or troubleshoot broken gear.

The SAFE kit includes two spring-loaded test clips for probing circuits and a 1/4" output jack for connecting to an interface. Use it in conjunction with free oscilloscope software (Soundcard Scope) to turn your audio interface and computer into a low-voltage, audio-only (no DC) oscilloscope. The circuit is completely passive and as such requires no power—not even batteries!


  • Protects against DC, over-voltage, and electro-static discharge
  • Input volume control
  • Spring-loaded clip probes
  • Unbalanced 1/4" output
  • Tiny and easy to build
  • Cheap!

Use SAFE to…

  • Test your DIY build before plugging it in for real
  • Troubleshoot your DIY project or broken gear
  • Hear your experimental circuit without risking damage to your interface