SMSL SH-6: Not attaching ground terminal dangerous?

[S0_B00sted]

Hello,

I'm looking to purchase a headphone amp. I'd like to be able to use the amp with my PC38X headset while plugging the mic into the onboard audio on my motherboard since it's just for voice chat and doesn't need to be super-high quality. I'm worried this will cause a ground loop.

The SMSL SH-6 has a ground terminal on the back that you attach from the power cord. I assume not attaching this would prevent a ground loop. The amp would be connected to a to-be-decided DAC which would be connected to my PC which is obviously grounded via USB. Would this also ground the amp, making the ground terminal unneccessary or would it still be dangerous not to attach it?

Obviously I'm not super knowledgeable about electronics.

 

[Holmz]

What comes into the SMSL SH-6?
12V, 230v, 230v…

Touching a 9V battery to the tongue cans test them, painfully.
At 230v it is deadly.

 

[Doodski]

What comes into the SMSL SH-6?
12V, 230v, 230v…

Touching a 9V battery to the tongue cans test them, painfully.
At 230v it is deadly.

I can just imagine a peep taking a hit on the tongue of 230VAC. Convulsing and then choking on whatever was eaten last. Horrible. My father was a industrial firefighter paramedic and he attempted to save a electrocution victim. He ended up with a mouth full of vomit via CPR and he still tried to save him.

 

[Holmz]

@Doodski maybe once?

It looks like it is double insulted with only a two prong 100-250v input, so the post if there to help with ground loops.
Hence you have to try it both ways.

If it was used as a preamp to drive powered speakers, then one can still get a ground loop through the RCAs.
So you may need to ground it in both directions.

But just try it without anything first. It should be OK.

 

[S0_B00sted]

@Doodski maybe once?

It looks like it is double insulted with only a two prong 100-250v input, so the post if there to help with ground loops.
Hence you have to try it both ways.

If it was used as a preamp to drive powered speakers, then one can still get a ground loop through the RCAs.
So you may need to ground it in both directions.

But just try it without anything first. It should be OK.

Got it. Looking at it I wasn't sure if it was for safety or if it was just for helping with ground loops. Thanks!

For future reference with other amps, it should not be assumed that they will be grounded just by being connected to something else that is grounded?

 

[AnalogSteph]

For future reference with other amps, it should not be assumed that they will be grounded just by being connected to something else that is grounded?

They generally are, unless you have gone to the trouble of using a galvanically isolated connection (e.g. by using an isolation transformer).

IEC Class II devices should never generate more than a bit of mains leakage and are designed to be safe without a PE connection; expecting audio connections to potentially carry fault current would obviously be unsafe. They'll drain the mains leakage of a few nF worth of filter capacitors fine though.

It is unusual to find a ground terminal on such a headphone amp at all. Presumably this is for cases where you're running a Toslink connection into a DAC that's also Class II, so the whole setup would end up floating. If you've ever noticed hum in headphones that went away after touching the headphone amp's case or audio ground, that's the kind of issue this can solve. The internal supply is likely to be of the switching kind, which generally have more mains leakage than a traditional transformer plug pack due to mains filter components. Amplifiers like the Schiit Magni range, Topping L30/L50 and JDS Labs Atom are all using old-fashioned transformer supplies for this reason.

 

[grogi.giant]

I'm worried this will cause a ground loop.

No, the other way around. If you don't have ground connected, it cannot have a loop...