Okay to plug in a phantom mic with the power turned on?

B

Brackish

New member
I've heard it both ways. Someone
has told me they've always left the
power on with no problems.
Anyone know the truth about this?
 
Plug the mic in then let the phantom charge up. Then turn the phantom off and wait atleast a minute before you unplug.
 
the only problem that can occur is arcing between the terminals as you plug the mic in. This will act like turning phantom power on and off a few times at the speed of light. This wont damage anything really but it's probably better keeping a load (microphone) attached before turning phantom power. It wont damage the mic, but put excessive strain on the regulated phantom power supply which isn't enough to harm it.
 
it's possible that you could damage your mic while disconnecting the xlr plug if the phantom power is on. some plugs fit tighter than others and your hands could slip while handling the mic and cable, which could damage the diaphragm if you bump the mic hard enough. i'd play it safe and kill the phantom power before connecting/disconnecting any condensor mic.
 
Two jobs ago, a coworker killed a 441 by unplugging it from the cable while phantom power was still engaged.

Better safe than sorry.
 
Sometimes there is no choice when you can't do phantom on a per channel basis. For instance, when I used to track drums all I had was a Mackie 1604 which is either all channels on or off. So I had to have phantom on dynamics or my OH condensors would be very sad. :)
 
In general, things will not get damaged, but the possibility is there, so I would trun the phantom power off first. I can not see any reason why you should not be able to, so why not get in the habit?
 
Well if you somehow short Pins 2 and 3 together when plugging in the Mic you can blow the Phantom power regulator in the Power supply....

How do I know this?? Well I did it yesterday by accident and I also did it a couple weeks ago by accident.....
Yesterday I was finnishing off building my Green Pre amp and I was testing the Phantom power and by accident i put the Probes of my DMM on pins 2 and 3 instead of 2 and 1 (Ground) which shorted the pins together and caused a Big spark which blew the LM317 Regulator and caused the Phantom power to jump to over 70v which can blow many Condenser mics.....

How did my green Pre amp turn out?? well I still have to do some trouble shooting on a Noise problem in one channel but the other Channel sounds AWESOME!!! I have never heard a Pre with that sort of Clarity and it sounds so Clean and I can hear things that I wasn"t able to hear before.....

It is definately the Best sounding Pre I have ever heard (I haven"t heard very many) and it makes me want to build a bunch more.......

I will post some samples once I get the other Channel working properly....

Cheers

PS: also be ware that it can sometimes take over a Minute for the Phantom power to turn off completely (Residual Charge in the Capacitors) so it is allways good to turn off the Phantom and wait a couple minutes before pluggin in a Mic....
 
Minion said:
Well if you somehow short Pins 2 and 3 together when plugging in the Mic you can blow the Phantom power regulator in the Power supply....

How do I know this?? Well I did it yesterday by accident and I also did it a couple weeks ago by accident.....
Yesterday I was finnishing off building my Green Pre amp and I was testing the Phantom power and by accident i put the Probes of my DMM on pins 2 and 3 instead of 2 and 1 (Ground) which shorted the pins together and caused a Big spark which blew the LM317 Regulator and caused the Phantom power to jump to over 70v which can blow many Condenser mics.....
Click to expand...

That doesn't sound quite right . . . the regulator should have been protected by the 6.8k resistors, and anyway those two resistors are sourced from the same point (the 48V rail), so shorting them shouldn't do anything. Also, the resistor between a multimeter's leads is about 1M usually, so it wouldn't be a short anyway.

So if your regulator blew up, I would recheck the circuit connections before you power up again.
 
Well after changeing the Regulator It works properly but if I short the + and - rails It blows the Phantom regulator...I have done this twice now(from being clumsy with my DMM) but it works just fine now as long as I don"t short the + and - Pins.....

Actually from reading the Green Metta at Prodigy Pro this is a Common thing with this Power supply.....

The Power supply for the Phantom is a Pluss and Minus supply (at least that is what my DMM says, When I put the DMM on ground and Pin 2 I get + 47.5v and when I put the DMM on pin 3 and Ground I get -47.5v) and doesn"t shorting the Positive to the Negitive cause a Short curcuit no matter what the Current is??


Cheers
 
Minion said:
The Power supply for the Phantom is a Pluss and Minus supply (at least that is what my DMM says, When I put the DMM on ground and Pin 2 I get + 47.5v and when I put the DMM on pin 3 and Ground I get -47.5v)
Click to expand...

It shouldn't be like that. Phantom is +48VDC on pins 2 and 3. There is a spec for higher voltage phantom power, but it's only used by sexy expensive German mics (loosely speaking).

I think I found the schematic for the phantom power supply. I don't really get the need for 100VDC. Generally it's easier on a regulator if the incoming voltage is close to the desired output. The language on this page about resistors getting hot, etc.,

http://www.diyfactory.com/projects/green/green.htm

Doesn't give me warm fuzzy feelings about the design.
 
Actually I might be getting +47.5v on each pin , I might have just had the Polarity of the DMM backwords...

The PSU runs off of a +/-15v Supply so it uses a voltage doubler/rippler a couple times over to get up to between 60-70v and then the LM317 regulates it to 48v...

One thing I notice about the LM317 is it is extremely sencitive to any shorts or reverce voltage being applied and even the Slightest bit can cause it to blow....

I was thinking of putting in a Diode to protect against reverse voltages but I don"t know if the Diode will pass the audio signal that is going the other direction....

The one channel that works though sounds "Super Sweet" ,Unlike any pre I have really ever heard before , but then again I don"t have many pre"s to compare it to, but I know what I like and It definately sounds awesome....

I"m going try re-grounding the noisey channel and see if it helps with the noise...If that doesn"t help i might try putting in a Freebe Toroidal Transformer I got today and see if that helps but I don"t see how one channel would get interferance and not the other, It might also be that I haven"t set the CMRR but I don"t have a Scope so I can"t do it.....


Cheers
 
i saw that 441 and i read it as 414 so i didn't even notice, my brain autoreconfigured the transposition subconsciously leading me to the correct interpretation.
 
You must log in or register to reply here.
Back
Top