1. Register NOW and become part of this fantastic knowledge base forum! This message will go away once you have registered.

phantom power with condensor mics

Discussion in 'Microphones' started by softscrubmonkey, Nov 4, 2004.

  1. hi im brand new here and i just have a question about phantom power with condensor mics. i have an MXL 990 mic and it says it runs on 48v phantom power but is it possible to run into my friends mixer that has 15v phantom power or would that be bad? thanks for any help.
  2. johnwy

    johnwy Well-Known Member

    Jan 6, 2003
    Smithtown, NY
    Home Page:
    the only risk you may have is a reduced amount of headroom, or maybe just wont work at all. you may want to invest in a seperate phantom power box (like Rolls or Audio-Technica), which can range about $75-$100.
  3. EricK

    EricK Guest

    Clearly stated on the MXL 990 product page on their web site:

    Power Requirements: Phantom Power 48V ±4V

    Probably appears in your manual as well. It means the mic requires 44-52v to operate within spec. Chances are your won't get anything out of the mic with your friend's 15v.
  4. ghellquist

    ghellquist Guest

    My limited experience is that mics generally do run down to about 15V. If by run you mean that they make signals on noise entering the blunt end.

    Some of the mics I have tested sound exactly as with 48V phantom, some show really interesting problems, especially with loud signals.

    I have never seen anything break when having too low phantom power (too high is another thing, that breaks stuff).

    So go ahead and test.

  5. Clayphish

    Clayphish Active Member

    Nov 14, 2004
    Just make sure you don't use dynamic mic's with phantom power, especially over a long period of time (like a month or 2).

  6. RandomGuest

    RandomGuest Guest

    Feb 10, 2001

    You're not going to hurt them by hitting them with phantom power, the output transformer insures that.

    Not only that... but ribbon mics and phantom power get along just fine too.

    No $*^t.

    There are 1/4 million dollar consoles where you can't turn off the phantom power [like a Neve 8078]... so, are you only supposed to use condenser mics with those desks?

    Dude, if you're not an old wife... lay off the "old wives tales"... they'll rot your mind.

  7. Davedog

    Davedog Distinguished Member

    Dec 10, 2001
    Pacific NW
    Dynamics requiring no phantom power will simply ignore any phantom power present..And the possibility of damage to them is nil...void....nada....see Fletchers reply...Lets not start any old wives tales here on my forum...hmmmmm!
  8. Clayphish

    Clayphish Active Member

    Nov 14, 2004
    I don't know 100% the technical aspects of the problem but I had a electronics teacher tell me that phantom power normally is capable to run through a dynamic mic without any problem developing if the dynamic mic has no issues with inconsistent resistance through it's circuit. The problem he said was when a mic's resistors are not up to spec. I suppose this means that the resistance applied between the 2nd and 3nd pin are inconsistent to one another (one being below it's rating) which then causes a portion of the DC voltage to flow through the coil or ribbon rather then out the ground (pin 1). He went on to say that with prolonged use, the microphone will show signs in reduced high frequency response. When questioned on the topic he said that it was ok to use dynamics with phantom power, but as a precaution it would be wise not to let the mic sit with phantom power running through it when it wasn't in use.

    Anyways, maybe I got it wrong, so if any of you with electronics background can contribute, that would be great. Please comment on any of my inconsistencies as well. My teacher was who taught it, not me.

  9. Cucco

    Cucco Distinguished Member

    Mar 8, 2004
    Fredericksburg, VA
    That theory is 100% correct. The only problem is that it applies to ribbon mics, not dynamic mics. And even then, as Fletcher mentions, it's okay to hit a ribbon with phantom power. Very few ribbons are in the category of "inconsistent resistance."

    Now, the real question is, can you feed phantom power to the output of another mic pre? The way phantom power is applied, you should be able to do this, I just haven't had enough balls to test the theory!

    Fletcher, Davedog???
  10. RandomGuest

    RandomGuest Guest

    Feb 10, 2001
    To the output of a mic pre?

    If the pre has a transformer balanced output or blocking capacitors it will... if it's like that TL Audio piece of snot you'll blow the output chip in under a NY minute.

    If phantom power is miswired it'll ^#$% up the element in any microphone not just a ribbon or a dynamic. However, if the phantom power is wired correctly [+48 vdc on pins 2 and 3 of an XLR with the "0 volt" reference being Pin 1 of the XLR] you're fine.

    A transformer will not pass DC. The way a transformer works is that with alternating current you make and break the magnetic field created by the primary windings around a magnet... as you make and break this magnetic field a current is induced to the secondary windings of the transformer. DC is a flat line, it will not "make and break" the magnetic field so no current is induced to the secondary winding... in other words, it can't pass DC. If you have improperly filtered DC with a bunch of ripple on the rail you might have a problem but those kinds of problems are really few and far between.

  11. JeffreyMajeau

    JeffreyMajeau Active Member

    Sep 5, 2000
    Fletcher, I wanted to thank you for explaining this to be back in June. I'm going through a period of burnout in this industry with all the BS that flies.

Share This Page