Grounded Macbook

**Daniboy** · 09-07-2015, 04:36 PM

I use a 13" Macbook Air, which has a 45W MagSafe charger.

This charger comes with 2 power conectors, one big cable that is grounded and a little adapter which is not grounded.

How important is grounding the Macbook while playing? Is it ok to not use the grounded cable?

Thanks.

**nem0nic** · 09-07-2015, 06:11 PM

Typically it's good to ground any electrical device. But if you ever hear a hum in your audio, it's worth a try to switch out to the ungrounded adapter.

**Daniboy** · 09-07-2015, 07:13 PM

Originally Posted by nem0nic

Typically it's good to ground any electrical device. But if you ever hear a hum in your audio, it's worth a try to switch out to the ungrounded adapter.

Really? Just before reading "ungrounded adapter" I could swear you would say "grounded adapter". I didn't know the ground wire could cause hum. Thanks for the info.

**barstarsounds** · 09-07-2015, 07:45 PM

i was under the impression that as long as they were all at the same potential to ground (same circuit) then it would decrease the chances of a hum?

**nem0nic** · 09-07-2015, 09:10 PM

Grounding can cause a hum for 2 common reasons. First, you can have a ground loop. In any DJ booth-type situation, there are going to be multiple paths to ground. And multiple potentials, creating a ground loop. This manifests itself as a constant hum that is the frequency of your AC waveform (audio samples here).

Second, a lot of devices will dump "noise" down a ground line. This is usually switching noise (like a refrigeration unit or a fog machine) or otherwise poor electrical design on devices attached to that ground. This can manifest itself and any kind of crazy noise - from morse code sounding chattering to tweeter popping snaps and woofer blowing pops. I had a computer once that was super quiet unless I used the trackpad - in which case it would chatter like R2D2 having a stroke. Thanks HP.

So yeah, sometimes dropping the ground is a good way to go. But hey, I also like not getting shocked. So my rule of thumb is only drop ground if you are addressing a noise issue. And then only until you figure out a better solution. In the US, there are some great products that can fix ground loops without fucking up your audio quality or dropping the ground (Ebtech HumX for example).

**SirReal** · 09-07-2015, 11:43 PM

Actually, you mean "lift" the ground. Meaning to not ground. Dropping the ground, technically, means to ground something. Just didn't want any confusion. Always ground electronics and sound gear. If there's a hum then you can cycle though testing your gear until you find the "culprit" of the loop and lift it's ground.