PHANTOM POWER: Will turning unit on/off with mic plugged in, fry the chip?

[markwesse]

I have just had to pay $200 to have the mic preamp/phantom chip replaced...ok its fragile. This happened before I got it (2nd hand) when the guy was demoing and plugged a dynamic in with phantom on and it killed it.

 

So my question is, does the frailty extend to having a mic plugged in, with phantom on and then booting. Do I sit there in terror at a gig while it boots, praying that the phantom wont die? (since I use a pga181 for live vocals...which is actually brilliant btw)

 

[brue58ski]

I have never heard of either scenario. Are you sure the guy was truthful when describing how the chip got burned out.

[Schmalle]

I can't comment on what actually caused the "frying of the chip" without knowing the circuit (and mic and cabling).

 

But here is an educated guess of the cause:

When you plug in a mic then two the XLR contacts are connecting only roughly simultaneously. It's possible that plugging in a electrostatically charged mic isn't connected to ground for a very short moment and discharging happens partly through the phantom power circuit - it's only a small fraction of a second but the current might be high enough to damage something in the circuit.

 

So taking this hypothesis seriously there is no need to fear when the mic is already plugged in.

It seems to be a good rule of thump to put the phantom power off before you plug or unplug a mic.

[datacommando]

On 11/15/2023 at 10:21 AM, markwesse said:

So my question is, does the frailty extend to having a mic plugged in, with phantom on and then booting.

Hi,

 

There appears to be very little specific info about this subject, other than this statement from the Helix Owner’s Manual.

 

”IMPORTANT! Never connect the Helix device’s XLR outputs to a device whose XLR inputs have 48V phantom power enabled!”

 

Clear as mud!

 

Hope this helps/makes sense.

[brue58ski]

I asked about what the guy did because I've never heard of that before. And I've plugged many a mic into phantom power with no issues. 

[Schmalle]

On 11/15/2023 at 2:34 PM, datacommando said:

Hi,

 

There appears to be very little specific info about this subject, other than this statement from the Helix Owner’s Manual.

 

”IMPORTANT! Never connect the Helix device’s XLR outputs to a device whose XLR inputs have 48V phantom power enabled!”

 

Clear as mud!

 

Hope this helps/makes sense.

Not sure what the XLR outs have to do with the mic in.

[datacommando]

On 11/15/2023 at 6:27 PM, Schmalle said:

Not sure what the XLR outs have to do with the mic in.

 

Exactly - I think they must mean that if Phantom Power in the Helix is turned, on and you connect to FOH via XLR and that also has Phantom Power engaged.

[TLF2007]

I had to get the io board replaced in my Helix due to "hot swapping" condenser (48V Phantom) mics. Now when I use them, I plug it, turn it on. Use accordingly, then turn off and take the mic out 

[line-6-user]

On 11/15/2023 at 6:47 PM, TLF2007 said:

I had to get the io board replaced in my Helix due to "hot swapping" condenser (48V Phantom) mics. Now when I use them, I plug it, turn it on. Use accordingly, then turn off and take the mic out 

The same happened to me.

 

I also plug and unplug the same way as you do.

 

I always worry if it fries the chip again... Maybe the device could have been designed better?

 

[markwesse]

I have  been hot plugging/mute for 30 years and never an issue...EVER lol

Until...Helix.

 

I got it fixed and the tech said it was a pretty frail design. He had never replaced a fry due to hot plugging

Ribbons on phantom and bad cables...is a completely different thing :-)

 

Now I have to remember when setup is done at the gigs, not to let anyone plug my mic in (which is mostly for a custom mic on guitar) until everything is booted...yet another management issue!

 

Its from the studio but it really works live...esp on 12 string...SDCs rule!