Phantom Power | Broken Condenser Mic

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Phantom Power | Broken Condenser Mic

Post by apaclin »

Hi, apparently I broke a Neumann TLM103 mic by plugging it in with the phantom power already on. It made noise for a while after a did that and then produced either no sound or an occasional noise when moving the XLR cable. The cable is fine, I tried dynamic with it already.

What could be actually broken in the mic and can it be fixed?
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Re: Phantom Power | Broken Condenser Mic

Post by James Perrett »

It would be worth trying the cable with another phantom powered mic as a dynamic mic doesn't need all the cores to work. Or check the voltage on the cable at the mic end between pins 1 and 2 and then 1 and 3. The phantom power supply in your mixer/interface/preamp could just as easily be the problem here.
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Re: Phantom Power | Broken Condenser Mic

Post by Hugh Robjohns »

apaclin wrote: Sat Oct 16, 2021 8:00 pm Hi, apparently I broke a Neumann TLM103 mic by plugging it in with the phantom power already on.

You'd have been spectacularly unlucky to have killed the mic that way! I've been hot-plugging mics for over 30 years and haven't killed one that way yet, and that included a pair of tlm103s i had for over a decade

It made noise for a while after a did that and then produced either no sound or an occasional noise when moving the XLR cable. The cable is fine, I tried dynamic with it already.


Sounds like your cable has a broken shield connection, or a nasty brand of XLR with sockets that don't mate correctly or reliably.

A dynamic mic will still appear to work normally without a shield (pin 1) connection, but a phantom powered mic won't.

What could be actually broken in the mic and can it be fixed?

I'd be very surprised if hot plugging killed the mic, but if their is a fault your local Neumann/Sennheiser agent will be able to help.

But first, I'd find, borrow, or buy a new mic cable, and ideally one with genuine Cannon, switchcraft or Neutrik connectors, not cheap chinese knock-off connectors!
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Re: Phantom Power | Broken Condenser Mic

Post by apaclin »

Hugh Robjohns wrote: Sat Oct 16, 2021 8:56 pm But first, I'd find, borrow, or buy a new mic cable, and ideally one with genuine Cannon, switchcraft or Neutrik connectors, not cheap chinese knock-off connectors!

This is a custom Mogami 2534/Amphenol ac3f-ac3mm cable, which is a quality one. I already tried another condenser mic and it works. Weirdly I hot plugged TLM103 many times and it worked, but not this time...
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Re: Phantom Power | Broken Condenser Mic

Post by MOF »

If another condenser microphone works then it’s not the cable. Just check that the xlr contacts are clean, if that doesn’t work then it looks like it will need repairing.
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Re: Phantom Power | Broken Condenser Mic

Post by Hugh Robjohns »

apaclin wrote: Sat Oct 16, 2021 9:24 pmThis is a custom Mogami 2534/Amphenol ac3f-ac3mm cable, which is a quality one.

Quality cables break too, and connector sockets tarnish or lose tension...

I already tried another condenser mic and it works.

That implies all three cable connections are intact, but doesn't rule out connector tolerance problems... so I'd want to try an entirely different cable with different connectors, just to be sure. I've been caught that way before!

But if the mic still doesn't work on a different cable, you really have been spectacularly unlucky.

The mic's transformerless output driver (and electronically balanced preamp inputs) can be damaged by hot plugging on jack plug patchbays because of the high voltage spikes that result from shorting supply capacitors on plugging/unplugging. But there is no shorting action when plugging/unplugging via XLRs... hence spectacularly unlucky.

It will need the services of a qualified and experienced mic fixer. Commiserations.
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Re: Phantom Power | Broken Condenser Mic

Post by apaclin »

Hugh Robjohns wrote: Sun Oct 17, 2021 10:06 pm
The mic's transformerless output driver (and electronically balanced preamp inputs) can be damaged by hot plugging on jack plug patchbays because of the high voltage spikes that result from shorting supply capacitors on plugging/unplugging. But there is no shorting action when plugging/unplugging via XLRs... hence spectacularly unlucky.

It will need the services of a qualified and experienced mic fixer. Commiserations.

Already tried two different cables.

Well, then I'm proud that I'm spectacularly unlucky. It makes me very unique 😂
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Re: Phantom Power | Broken Condenser Mic

Post by Wonks »

Have you tried it in a different interface or mixer? And what is the interface you are using that the mic is plugged into?

Have you got other mics using phantom power also plugged in at the same time? If so, can you try it with them unplugged and the TLM as the only mic?

The TLM103 has a relatively high current draw of 3mA. Some mixers and interfaces struggle to provide the full P48 current if there are several phantom mics plugged in.

The ones that take less current will continue to work whilst the higher current draw ones can stop working.

Or it may be that the P48 supply in the interface/mixer/preamp has developed a fault and isn’t providing the full voltage or current.

It may well be that the mic is faulty, but as it is a ‘high’ current draw mic, then the P48 supply could be the cause of the problem. So unless the other condenser mic you tried was also a TLM103, it’s worth trying it on a different interface or mixer of a type different to yours.
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Re: Phantom Power | Broken Condenser Mic

Post by Hugh Robjohns »

Wonks wrote: Mon Oct 18, 2021 7:46 amThe TLM103 has a relatively high current draw of 3mA. Some mixers and interfaces struggle to provide the full P48 current if there are several phantom mics plugged in.

You're absolutely right to suggest trying a different mic preamp or interface, as it is just possible that the phantom supply is failing and supplying too low a voltage for the TLM... but I fear the mic ist kaput.

But I'm not sure it's fair to say the "the TLM103 has a relatively high current draw of 3mA". The spec allows for up to 10mA, so I'd say 3mA was a pretty modest amount.

Just in the interests of research, I've done a quick search of the Microphone Data web database to find out how many capacitor mics fall into each mA increment of current consumption.

0mA< 123 mics >1mA
1.1mA< 258 mics >2mA
2.1mA< 162 mics >3mA
3.1mA< 207 mics >4mA
4.1mA< 73 mics >5mA
5.1mA< 36 mics >6mA
6.1mA< 12 mics >7mA
7.1mA< 22 mics >8mA
8.1mA< 3 mics >9mA
9.1mA< 75 mics >10mA
10.1mA< 3 mics >14mA

As you can see, there are a lot of mics that require between 1 and 2mA, but almost as many that need between 3 and 4mA. The number of mics that need more than 4mA is a lot lower, but many of those are very popular models!
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Re: Phantom Power | Broken Condenser Mic

Post by apaclin »

Wonks wrote: Mon Oct 18, 2021 7:46 am Have you tried it in a different interface or mixer? And what is the interface you are using that the mic is plugged into?

Have you got other mics using phantom power also plugged in at the same time? If so, can you try it with them unplugged and the TLM as the only mic?

It's Apollo Twin 2015. I tried TLM on it's own.
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Re: Phantom Power | Broken Condenser Mic

Post by apaclin »

We fixed it gaiz! And the solution was trivial, there was a cable inside unplugged, that connected the parts and we just plugged it in! Probably unplugged due to previous falls.
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Re: Phantom Power | Broken Condenser Mic

Post by Hugh Robjohns »

:bouncy: Wow! Glad you found it and it was such an easy fix.

And the moral is... never drop expensive capacitor microphones! :lol:

Also good to know that you weren't spectacularly unlucky with hot-plugging, after all!
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