Sennheiser MKH 816T Question

[mik...@hotmail.com]

Greetings all,

A coworker came to me with a question I can't answer. I'm hoping someone here might be able to help.

We have an old Sennheiser MKH 816T shotgun mic in our production cabinet. These mics use the older type of phantom power--12 volt T.

Now, I do know they are not compatible with traditional 48 volt phantom--unless the proper adapter is used. I'm also guessing plugging one into a 48 volt supply may damage the microphone.

Well...without asking anyone first, my coworker says he went ahead and plugged it into a mixer equipped with 48 volt phantom power to test it. Nothing happened.

He then came to me and asked if he might have trashed the mic, by doing this? I've never used a mic like this, so I really have no idea of possible consequences.

We do not currently have the necessary adapter to covert 48 volt phantom to the 12 volt T type supply, so I can't test it, to see if the mic has been damaged.

Anyone here able to comment on the likelihood of the mic being damaged by this? If damage is unlikely, would it be worth ordering the necessary adapter & putting this older mic back into use?

Thanks in advance!

Mike

[Scott Dorsey]

<mik...@hotmail.com> wrote:
>We have an old Sennheiser MKH 816T shotgun mic in our production cabinet. These mics use the older type of phantom power--12 volt T.
>
>Now, I do know they are not compatible with traditional 48 volt phantom--unless the proper adapter is used. I'm also guessing plugging one into a 48 volt supply may damage the microphone.
>
>Well...without asking anyone first, my coworker says he went ahead and plugged it into a mixer equipped with 48 volt phantom power to test it. Nothing happened.
>
>He then came to me and asked if he might have trashed the mic, by doing this? I've never used a mic like this, so I really have no idea of possible consequences.

He might have. The problem is that the output blocking capacitors aren't
rated for 48V on those, and momentary application of 48V will make them fail.

>We do not currently have the necessary adapter to covert 48 volt phantom to the 12 volt T type supply, so I can't test it, to see if the mic has been damaged.
>
>Anyone here able to comment on the likelihood of the mic being damaged by this? If damage is unlikely, would it be worth ordering the necessary adapter & putting this older mic back into use?

You should definitely order or make the adaptor (although note that if you
run this off a real T-power supply instead of the phantom-to-T adaptor it
will be harder to overload), just so you can see if it's damaged.

These mikes will run on 9V so you can put a 9V battery in a Bud box with
a couple connectors, a resistor, and some DC blocking caps and have something
good enough for test purposes. (It will overload more easily with 9V though).

It's a weird microphone but it's a real lifesaver outdoors. You don't see
them very often because wireless packs now get used on wide shots where
before we would have used a long shotgun, and because they are a pain if you
are trying to boom and mix at the same time (and these days we get some poor
sod booming, mixing, and operating camera at the same time). But I think
they are worth trying.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Peter Larsen]

On 25-07-2014 20:35, mik...@hotmail.com wrote:

> We have an old Sennheiser MKH 816T shotgun mic in our production cabinet.
> These mics use the older type of phantom power--12 volt T.

NO, this is important, NO, it is NOT using any type of phantom power. It
uses Tonleiter. Because of that you should KEEP the t�chel cabeling
standard until the phantom to tonleiter powerconverter that you purchase.

> Now, I do know they are not compatible with traditional 48 volt
> phantom--unless the proper adapter is used. I'm also guessing
> plugging one into a 48 volt supply may damage the microphone.

This is why it is imperative to let tonleiter run on DIN standard plugs.
Electrically they are better anyway, as long as it is the t�chel
version. You never hear wiggle-noises on those.

> Well...without asking anyone first, my coworker says he went ahead
> and plugged it into a mixer equipped with 48 volt phantom power to
> test it. Nothing happened.

You do not know that nothing happened. Keep your distinctions very
clear, technology can be unforgiving.

> He then came to me and asked if he might have trashed the mic,
> by doing this? I've never used a mic like this, so I really
> have no idea of possible consequences.

Phantom powering is a really ingenious concept, so the most likely is
that nothing happened.

> We do not currently have the necessary adapter to covert 48 volt
> phantom to the 12 volt T type supply, so I can't test it, to see
> if the mic has been damaged.

Buy it! - yes, it is THAT simple. Phantom-2-Tonleiter converters aren't
even expensive.

> Anyone here able to comment on the likelihood of the mic being

> damaged by this? - If damage is unlikely,

It is not probable, but I do not want to rule it out, simply because the
highest voltage the mics electronic components expect is 12 volts and
the design pre-dates phantom. It is nowever not probable because there
is no voltage difference that can drive a current unless the input(! -
output if you so want) on the mic is specifically designed to extract
the 48 volts.

> would it be worth ordering the necessary adapter & putting this
> older mic back into use?

The adapters aren't very costly, so you can afford to risk buying one.
In a lot of contexts it is the FIRST go to mike for vox at a distance,
so yes, it should be in use and the decision to leave it unused is of
questionable competence.

In the unlikely event that the mic needs servicing is is probably well
worth it. Do not drop MKH 1xx, 4xx and 8xx microphones, it can lead to
the FM crystal physically breaking. I know this because a friend of mine
replaced the crystal in one of his 406'es.

> Thanks in advance!

Crossing my fingers for a fine audio tool.

> Mike

Kind regards

Peter Larsen

[Sean Conolly]

"Peter Larsen" <dig...@hotmail.com> wrote in message
news:53d2bb5c$0$23224$edfa...@dtext01.news.tele.dk...

> On 25-07-2014 20:35, mik...@hotmail.com wrote:
>
>> We have an old Sennheiser MKH 816T shotgun mic in our production cabinet.
> > These mics use the older type of phantom power--12 volt T.
>
> NO, this is important, NO, it is NOT using any type of phantom power. It
> uses Tonleiter. Because of that you should KEEP the t�chel cabeling
> standard until the phantom to tonleiter powerconverter that you purchase.

Apparently there was a period when these were produced with T12 power and
XLR connecters, which is just an accident waiting to happen with all the P48
gear now.

For the OP - there's a chance that the mic went into the closet because it
didn't work the last time someone tried it on P48.

Sean

[mcp6453]

Since the 48 volt phantom power is fed through 6.81K resistors, isn't there a good possibility that the voltage actually
reaching the electronics is limited and the mic is not damaged? Why wouldn't the 816 have overvoltage protection?

[Scott Dorsey]

mcp6453 <mcp...@gmail.com> wrote:
>
>Since the 48 volt phantom power is fed through 6.81K resistors, isn't there a good possibility that the voltage actually
>reaching the electronics is limited and the mic is not damaged?

It's current limited, and that helps a lot. Does it help enough? Usually,
but not always.

> Why wouldn't the 816 have overvoltage protection?

Because it was designed before 48V phantom existed.

[Sean Conolly]

"mcp6453" <mcp...@gmail.com> wrote in message
news:rNCdnesybuJjgEnO...@giganews.com...

As Scott said - it was designed before P48 was a consideration, so it's just
a matter of how much over-voltage the designers thought was prudent - 2x, 4x
... ?

Plus one of the pins with 48v is supposed to be a ground for the 12v, so it
raises the possibility of reverse biasing a component somewhere, depending
on what they did with pin1.

Just speculation on my part, but enough that I wouldn't want to take bets on
the results.

Sean