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Any 48v ph power schematics available?


stephane

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Can you stand the physical size of five 9 Volt batteries? If so, it would only require 5 batteries, two 1% (or better) 6.8k resistors and two 50 Volt 22uF or larger caps. Batteries would run for about 200-400 hours.

Best,

Larry F

Lectro

Anyone know of a schematic for a portable 9v battery operated 48v phantom power supply. Would this be easy to make?

Stephane

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Possibly.... I was hoping for a single 9v battery unit for the smallest practical size, but if a 5 x 9v setup is a simpler design then I may just go that direction.  I'm assuming a single battery unit would increase the complexity of the design, and (from what I've read on the web) the s/n noise as well. Is that right?

But simpler is better. So, if I do go ahead and try to make this 5 battery phantom power box, how would I wire the caps and resistors?

Stephane

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  • 2 months later...

I smell some marketing voodoo here.

It would be interesting to see what the actual voltage is with "phantom power for electret condenser microphones". The EE in me says that it may be closer to a 12v supply instead of a 48v. I've been happily surprised in the passed though.

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" what the actual voltage is with "phantom power for electret condenser microphones" "

meaning voltage requirements??

it depends!

you must check the specifications of the microphone in question.

Some require the original spec full 48 VDC to operate properly, others follow the amended spec and operate properly on lower voltages, between 9 VDC and 52 VDC.

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  • 1 month later...

I got a Denecke box , works great! Word on the street is that a MC-60 cable for lectrosonics UM400 provides Phantom power. http://www.bhphotovideo.com/c/product/533394-REG/Lectrosonics_MC60_MC_60_XLR_Female_to.htmlt

It's mis-leading how b&h posts that there is phantom power. This is actually 5v bias for electret condensors

http://wanderingear.net

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"Phantom power" is an industry standard (including a wider voltage range sub-standard) for providing 48VDC to equipment --typically microphones-- via a balanced, floating, shielded connection.

The term "phantom powering" has been misused to describe adding a DC voltage over an unbalanced, coaxial connection to the point of becoming a generic term for any DC powering over an otherwise AC connection.

Caveat Emptor!

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I smell some marketing voodoo here.

It would be interesting to see what the actual voltage is with "phantom power for electret condenser microphones". The EE in me says that it may be closer to a 12v supply instead of a 48v. I've been happily surprised in the passed though.

Group, please correct me if I'm wrong, but the operative word in this quote is 'electret'. as opposed to a standard condenser mic. A standard condenser uses phantom power, not only to allow sufficient potential to support the audio voltage swing, but also to charge the condenser itself (establishing the 'zero' level). An electret condenser has a permanently (sort of) charge on the condenser, and the applied voltage drives an audio amplifier. Electret mics are much cheaper (inexpensive - some sound very well); the 'sort of' refers to what happens when a violently strong pressure wave at the diaphragm may actually fully discharge the electret, requiring a significant amount of time to recharge its condenser. A 'phantom' voltage refers to where the potential applied is between the hot and return, and the cold and return, so that there is no apparent voltage between the hot and cold (as opposed to T power, which is applied between the hot and cold). I believe the standard phantom voltages are 12VDC and 48VDC. DPA has mics that require a 'phantom' voltage of 140VDC. Electret mics require 3VDC to 5VDC. Some electret mics may be supplied by a true 48V phantom voltage, where 5V of the 48 are used to drive the internal amplifier, and the rest of the pressure is wasted.

Just decided to check my assumptions, and here are two good links:

http://en.wikipedia.org/wiki/Phantom_power

http://en.wikipedia.org/wiki/Condenser_microphone#Condenser_microphone

Jay

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" A 'phantom' voltage refers to where the potential applied is between the hot and return, and the cold and return, so that there is no apparent voltage between the hot and cold "

this it is hidden (aka phantom) from dynamic microphones.

More good info from Jay...

Recapping, Phantom microphone power is an industry standard specification, with some options*, but basically describes the method of sending DC voltage at low current to power microphones (Condenser and/or electrit condenser) power over the same balanced, floating, shielded cable as the audio is using.

*one option includes any DC voltage from 9-54VDC

Calling DC voltages on single wire shielded cables (unbalanced, coaxial) "Phantom" is not really the same, but is becoming an accepted generic usage, as in describing the RF amplifiers powered over the antenna coax as "phantom".

Edited by studiomprd
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  • 1 month later...
  • 1 month later...

" what the actual voltage is with "phantom power for electret condenser microphones" "

meaning voltage requirements??

it depends!

you must check the specifications of the microphone in question.

Some require the original spec full 48 VDC to operate properly, others follow the amended spec and operate properly on lower voltages, between 9 VDC and 52 VDC.

MKH50 requires 100V. I was surprised when I first time actually saw it on multimeter, even tho it was on 48v phanom....

I thought something was wrong with mic, but then I heard that it operates on 100V, I still can't get how it gets 100v out of 48v. Probably has some IC amp inside?

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