Why does a 1/4" jack short ground to the chassis?

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Hi. I believe it's common for 1/4in chassis mounted jacks to short ground to the chassis. I have one jack with a direct connection, another that makes a short when the jack is plugged in. I found this troublesome as it would mean that any fault earth current will flow through the return path of the output, it would also make it hard to avoid ground loops if my amplifier is connected to some dodgy signal source :\ I know there are plastic jacks that won't have this issue, but metal ones looks a lot cooler. Am I missing something here?
 

PRR

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There are MANY forms of "1/4-inch" jacks.

These are a cheapened form of telephone switchboard jacks. Telco jacks were often insulated frame in thick insulator panel. Our popular jacks cheapened the design to mount on metal chassis SOLIDLY.

They work great in simple systems where all "grounds" may return to chassis. They tend to work fine in headphones where the common wire is dubious anyway. In guitar amps some care is needed to keep rectifier and speaker currents out of tiny guitar signals.

As for safety: because you can touch the shell of a 1/4-inch plug, at least when part-in, you really should have that connected to a properly ground-bonded chassis. The metal bushing can be a robust bond. (Until the nut loosens.)

Various jacks have various switchings. Guitar jacks commonly ground the finger when the plug is yanked, so the idle amp won't buzz so much. Many other forms of switching are available.

The 1/4-inch, and its 1/8-inch children, are SO popular that you need to say a specific problem why it offends you. There are such problems, which is why XLR SpeakOn and other fancier connectors exist.
 
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