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-   -   Question about "phantom" (https://www.dvinfo.net/forum/all-things-audio/67688-question-about-phantom.html)

Ken McGrath May 18th, 2006 07:50 PM

Question about "phantom"
 
Does phantom power, by definition, mean a supplied voltage in the 11 - 48 V range?

When I put a 1.5V battery in my AT897 to power it (when using a Sennheiser 100G2 xmitter), is this not "phantom" power, even though it is powering the mic.

Finally, my Senn 100G2 receiver does not supply phantom power, but the supplied lav with mini connector still "works". How does it work if there is no phantom power? Is there a lower voltage supplied at the mini connector input that powers the lav?

Danny Natovich May 18th, 2006 09:33 PM

The term Phantom power is used for powering the mic from an external power source via the standard 3-wire mic cable, The power is 9 - 48v very low current according to the mic specs.

1.5v internal batt. is not phantom power.

Most WL transmitters supplies 1.5v-5v power to the electret condenser lavalier capsules, You can call it " Baby Phantom" if you like.

Danny.

Aaron Winters May 18th, 2006 11:00 PM

My turn, is there an advantage to phantom power? Other then not having the battery on the mic of course.

Danny Natovich May 18th, 2006 11:09 PM

Phatom power is better. It is constant, Batt. is not. It is safer, Batt runs out
some time.

If you look at mics specs. you will see better performance with Phantom in
mic that can be powered by int. batt. or phantom.

Quiz: Why "Phantom" ?

Danny.

Steve House May 19th, 2006 04:41 AM

Quote:

Originally Posted by Ken McGrath
Does phantom power, by definition, mean a supplied voltage in the 11 - 48 V range?

When I put a 1.5V battery in my AT897 to power it (when using a Sennheiser 100G2 xmitter), is this not "phantom" power, even though it is powering the mic.

Finally, my Senn 100G2 receiver does not supply phantom power, but the supplied lav with mini connector still "works". How does it work if there is no phantom power? Is there a lower voltage supplied at the mini connector input that powers the lav?

The ISO specification for phantom calls for either 24v or 48v. Virtually all manufacturers have gone with the 48v standard. Some mics are very picky and require very close to the full 48v while others, primarily those with permanently polarized capsules, can run on as little as 9v. For example, the Schoeps 641 and the AT 4053a both require the full 48v while the AKG Blueline mics will run fine anywhere from 9v to 48v.

No, the battery in your AT is not "phantom" power - phantom is fed over the XLR connector from the mixer or whatever the mic is plugged into.

Your Senn receiver doesn't supply phantom but transmitter does supply the power the attached lav mic. It's not really "phantom" power in that the spec for phantom defines not only the voltage level but also which pins carry the voltage. The phantom spec says that XLR pins 2 and 3 are each at +48vdc with respect to pin 1. FYI, the Sennheiser 500 series plugon transmitter does, in fact, supply true phantom power to the mic it's plugged into.

Steve House May 19th, 2006 04:42 AM

Quote:

Originally Posted by Danny Natovich
..

Quiz: Why "Phantom" ?

Danny.

Why use it or why call it "phantom?"

Danny Natovich May 19th, 2006 04:45 AM

Why is it called "Phantom Power"?

Steve House May 19th, 2006 06:37 AM

Quote:

Originally Posted by Danny Natovich
Why is it called "Phantom Power"?

Because the voltage is the same on the "hot" and "cold" signal lines, it vanishes like a phantom when viewed from the microphone capsule's perspective. That's why dynamic mics don't see it. The other type of powering, "A/B" or "T-power," puts 12 volts ACROSS pins 2 and 3 and a dynamic mic could let all its magic smoke and sparkly pixy dust escape if connected to it.

Ken McGrath May 19th, 2006 07:09 AM

Thanks so much for these explanations. I finally understand!!

A. J. deLange May 19th, 2006 11:33 AM

Quote:

Originally Posted by Danny Natovich
Why is it called "Phantom Power"?

Because the power is carried in a "Phantom Circuit". This derives from the old days of telephony when the phone companies would use this basic wiring scheme to create a "Phantom Circuit" i.e. a circuit which did not exist in the usual sense but could nevertheless carry a phone conversation. In the typical setup there would be two phone circuits, each wired like our balanced mics i.e. each with a phone at each end connected to the line through a center tapped transformer. Two circuits, two sets of phones. At each end a third phone would be attached between the center tap of the transformer on one circuit and the center tap of the transformer on the other (in a normal circuit the center tap would be earthed). Thus each pair would carry the signal from its phones in differential mode and the signal from the phantom phones in common mode. The company got a free circuit without having to string a third pair of wires.

When I was a lad working at the college radio station we would go out remote location and send the audio back to the studio over balanced phone line circuits. We had handsets connected between the center taps of the transformers and earth at each end so the studio guy and field guy could talk to each other over the same line that was carrying the program. This is another example of a phantom circuit in which the earth carried the phantom signal in one direction and the phone line pair carried it in the other. This is really what we have here. The phantom cirucuit carries the DC power to the mic.

David Tamés May 19th, 2006 12:54 PM

Check out some of the related threads on this topic:

Dynamic mics immune to phantom power?
http://www.dvinfo.net/conf/showthread.php?t=67611

phantom or no phantom?
http://www.dvinfo.net/conf/showthread.php?t=67672

ME66 need K6 with Beachtek?
http://www.dvinfo.net/conf/showthread.php?t=9064


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