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Re: Phantom Power. Question from The Ghost Who Walks :-)

Subject: Re: Phantom Power. Question from The Ghost Who Walks :-)
From: "Scott Fraser" scottbfraser
Date: Sun Jan 3, 2010 7:13 am ((PST))
<<One of the things I don't understand is how the range of voltage for
Phantom Power can vary between 9-52V DC and whether the voltage
difference makes an "audio" difference.>>

Officially Phantom power is 48 volts DC, but in the past a number of
lower priced mixing desks didn't bother to incorporate a power supply
providing a 48 volt tap in addition to the + & - 12 to 18 volt rails
needed for the circuitry. They started supplying Phantom voltages in
the range of 24 to 36 volts, which many condenser mics are happy with.
Neumann mics specifically (I know from personal experience) will not
operate at less than 48 volts without seriously compromised dynamic
headroom, but the makers of the less than fully pro desks gambled that
their end users would likely not also be using high end microphones.
Today it's quite rare to find less than 48 volts available on any mic
preamp. Generally speaking most mics will exhibit higher self noise &
reduced dynamic range when powered by less than 48 volts. Electret
condensers are usually less affected, since the Phantom voltage is
only running the impedance converter circuit, not polarizing the
diaphragm. Generally electrets running on an internal 1.5 volt battery
are rather noisy because they are designed to hit a low price point
resulting in a number of design compromises.

Scott Fraser

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