Subject:Phantom power question

Posted by: captn_spalding

Date:1/28/2004 2:02:30 PM

Is there any down side to using 18v for phantom power? Mostly Neumann's mic's which call for 48v.

..spalding

Subject:RE: Phantom power question

Reply by: Chienworks

Date:1/28/2004 2:25:04 PM

Most condenser mics i've ever seen will work fine anywhere from 16 to 48v. Quite a few are rated as low as 5v. Modern electret elements themselves probably only need 1 to 2v and the mic circuitry will drop most anything it gets down to this level. One of my mixers puts out 48v and another one puts out 12v. Every condenser i've ever had my grubby little hands on works perfectly well with both mixers.

Subject:RE: Phantom power question

Reply by: captn_spalding

Date:2/25/2004 10:15:26 AM

Chien: I read (on a Neumann Forum, I think) that "high end performanc suffers" if you drop much below 40v. Now, considering the source, I asked Neumann tech suppot and just got the specs read back to me. So, I guess i'm asking if your experience includes any Neumanns. Particularly K184 or U89?

..spalding

Subject:RE: Phantom power question

Reply by: Chienworks

Date:2/25/2004 10:34:37 AM

Captn, nope. Never had any of those to play with. Of course, there's nothing magical about 48V or 40V or 2V. It depends on what the preamp in the mic needs to do it's job well. 48V is mostly a hangover from the days when there was a tube amp right in the condenser microphone housing (i can't imagine that!) Modern solid state electrets need much less voltage. Of course, they have to be able to handle 48V without burning out, and how they handle this can vary from one mic to the next. Some may use a simple divider circuit and if you feed it too much less than 48v it won't get enough out of the divider circuit to power it. Others may use a voltage regulator or a zener diode to attenuate anything over their optimal voltage. The spec sheets for the Neumann mics probably list an acceptable voltage range.

Subject:RE: Phantom power question

Reply by: captn_spalding

Date:3/18/2004 6:56:30 AM

Just to bring closure on this topic - The Neumann's are running fine on18v.

..spalding

Subject:RE: Phantom power question

Reply by: Rednroll

Date:3/18/2004 1:40:10 PM

Just as a side note of information on the technical side. "Line level" outputs are usually at 1Volt RMS or 2.8 volts Peak to Peak. So to be able to reproduce an audio signal that is 2.8 volts Peak to Peak in a transistor/opamp type of mic, you need 2.8 volts of DC minimum. Typical phantom power is 48 Volts DC. So Chienworks is absolutely correct in the use of either a zener diode or a voltage regulator, where their job is to reduce the input voltage to the mics operating voltage. So you can easily see that most of that voltage for phantom power is just disappated accross the voltage regulator. Now mic levels are much lower than line levels, but I don't happen to recall that operating level off the top of my head right now. So basically you should have no problem running 18 volt phantom power, unless they use a resistor voltage divider as a voltage regulator, then you might run into some problems if it's looking for 48 phantom power.

Subject:RE: Phantom power question

Reply by: Chienworks

Date:3/18/2004 5:56:55 PM

Mic levels vary all over the lot, hence the trim/gain control on any mixer worth using. However, as a good starting figure i usually use 0.001 volts RMS for mic level. It's close enough to get started.