Does phantom power affect TRS connections?

[JoelB]

One would assume not, but I have a lot of gear plugged into TRS jacks on this device - Would prefer to use a few channels for microphones without having to unplug everything that is plugged in. Does phantom only work on XLR connectors on this machine? (I hope so...)

 

[Logrinn]

I have never heard of any equipment that has phantom power going to the line inputs.
Checking the block diagram in the manuals of both the Model 12 and Model 24 one can also see that it's only going to the mic inputs.

The manual (Model 24) also states:

"When phantom power is on, the PHANTOM +48V indicator lights, and phantom power is supplied to the MIC input jacks (1-12, 13/14-19/20)." (emphasis mine).

And for Model 12 it says:

"Press the MULTI JOG dial to provide phantom power to the MIC/LINE (BAL)/INST (1-6, 7/8 and 9/10) XLR connectors" (emphasis mine).

 

[-mjk-]

That drawing is whacked. It shows Channels 1 though 12 Line inputs are connected in parallel with the XLR inputs before the amplifier block. 13 through 20 are bridged after the amplifier block. Looking at the drawing, I'd put a DMM across the Line input and check it to make sure it's not really wired like that.

 

[Logrinn]

You're quite right. I read the block diagram wrong.
I'm still pretty sure there's no phantom power at the line inputs though, but like you said, it's easy to check with a meter.

Will do that and report back.

 

[Logrinn]

As I expected there wasn't any power when I measured the TRS input on my Model 12.

 

[-mjk-]

@Logrinn that diagram clearly isn't right, but your analysis of the statements in the user manuals was dead on. I too have never heard of phantom power on line inputs. Thanks for confirming that with the DMM.

 

[Charlemagne Kid]

Just got a M12 and in the manual, these two paragraphs seem to contradict each other. If I understand correctly, you can use a balanced dynamic mic while using PHANTOM, but what is the difference between a balanced and unbalanced dynamic mic? Is it just the type of connector you use?

- Turn the PHANTOM +48V switch on (pushed in) only whenusing a condenser microphone that requires phantom power. Turning the PHANTOM +48V switch on (pushed in) when a dynamic mic or other mic that does not require
it is connected could damage this unit and connected equipment.

- When using condenser mics that require phantom power and dynamic mics together, be sure to use balanced dynamic mics. Unbalanced dynamic mics cannot be used when phantom power is enabled.

 

[Arjan P]

Usually any mic you buy has a + and a - wire inside, and both are isolated from the ground connection (chassis). All have their own pin in the XLR receptacle, so +, - and GND. That is what's considered a 'balanced mic' in the above statement.

Some older mics, particularly notorious are old ribbon mics, do not have a separate ground connection, but have ground and minus together. If that is the case, this will short your phantom power supply. This power supply could be damaged, burned out - or it will have provisions against damage, but then still such a mic will be responsible for removing the phantom power for all other connected mics.

The first paragraph is not wrong in saying it's better to leave phantom power off if not needed, but generally speaking, a mic (and mic lead) that doesn't need phantom power but is wired the right way will have or cause no issues whatsoever. I'd say 99.5% of mics today are in that category.

 

[Charlemagne Kid]

Thanks Arjan, this helps clear it up. I only have one condenser mic and all others are dynamic. To be safe, my think my approach will be to use a preamp for the condenser and leave PHANTOM off.

Thanks again for the explanation....

-Mike

 

[Hammarlund]

Virtually all modern dynamic mics are balanced, if you bought it in the last decade it would be very surprising NOT to have it balanced

 

[Arjan P]

"Virtually all modern dynamic mics are balanced, if you bought it in the last decade it would be very surprising NOT to have it balanced"

Yeah, like I said, 99.5% of mics today.

 

[-mjk-]

I would qualify that statement by adding "with an XLR connector". I have 2 wired karaoke mics (they were free, lol) that have aa 6.5mm TS plug on them. You just know that someone would take something like that and use an XLR adaptor to plug it into a mic pre, and possibly blow it up with phantom power, lol.

There is another thread going on now about someone who wants to use the mic pre XLR connectors on an interface for a line level input in a unbalanced configuration. That exposes the connected equipment to the 48 volt phantom power supply. The results could toast the mic pre/interface, and the connected gear. It's not worth doing it like that.