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My Audio Probe

This is just a short post to explain the concept of an audio probe and the design I went with for mine

An audio probe is a common device in audio electronics which allows you to poke at a circuit and listen to the signal at that point, this lets you work through the signal path and pinpoint any faults 

While you could just connect a lead to an amplifier and poke the signal you risk damage to the amp with any DC that might be present at that point. While a lot of amps have an input cap which will block the DC it shouldn't be relied upon, for this reason we need to add our own cap

As you can see from the picture below the construction of an audio probe is pretty simple, I have a standard audio jack with a ground clamp which stays connected to the ground of the signal, I then have a 100nF capacitor going to a banana jack that lets me connect a regular multimeter probe. 



Some people take apart a lead or use the leg of the capacitor itself for probing but I've found that cumbersome or prone to noise, using a multimeter probe means your hand is physically isolated from what you're probing resulting in less noise and less chance of you zapping yourself

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