Mackie SR408 / SR568 Owner's Manual - Page 76

PHANTOM POWER DO & DON'T CHART DO DON'T If you are plugging in a condenser microphone, do verify that your microphone can be phantom powered. Don't worry about your other microphones as long their outputs are balanced and floating. Ensure that the microphone's output is low impedance, balanced and floating. This is especially important for vintage ribbon microphones like the RCA 44BX and 77DX. Don't connect microphones or devices that do not conform to the DIN 45 596 standard. Mute the sound system when turning the phantom power on or off, or when connecting or disconnecting microphones. If you forget, the resulting loud, nasty POP may be your last. Don't connect A-B or T-system microphones (another remote powering system) without suitable adaptors. Microphones that do not require power simply ignore the DC present between pin 2/pin 3 and pin 1. If you measure with a voltmeter between pin 2 and pin 3, you will read 0 Volts DC. This is what your dynamic microphone sees. Measuring between pin 2 and pin 1, or between pin 3 and pin 1, you will read the phantom power voltage, usually 48V, without a microphone connected. The dynamic microphone, as well as your balanced mixer input, ignores this voltage. Lately, the term phantom power has been perverted to refer to any remote powering system. In the strict sense of the DIN standard, this is not true. Furthermore, microphones or transducers that claim to use this system are not compatible with the DIN standard and will almost certainly be damaged if connected into such a system. Fortunately, these systems use tip-ring-sleeve phone plugs or miniature XLR connectors and they are usually associated with instrument pickup applications2. Phantom powering is defined in DIN standard 45 596 or IEC standard 268-15A. Your Mackie Designs mixer conforms to this standard. What works? To be compatible in a phantom powered system, a device (microphone, preamp with a microphone-style output, or direct box) must have a balanced and floating, low-impedance output. This includes all microphones commonly used for sound reinforcement and recording, such as the Shure SM58, SM57, Electro-Voice RE-15, RE-16, RE-20, ND series, Beyer M160, M500, AKG D224, D12, D112, and many others. If you are fortunate enough to own any tube condenser microphones, such as the AKG C12, Neumann U47 or U67, these microphones may be connected in a phantom powered system and will operate without regard to the presence or absence of phantom power. They will always require their external power supply (which must be plugged in and turned on). What doesn't work? The list is short: 1. Microphones with unbalanced outputs. 2. Microphones with grounded center-tapped outputs. Many old ribbon microphones were supplied connected this way. Have a technician lift the ground from the center tap. 3. High-impedance microphones. 4. Microphones that exhibit leakage between pin 2 or pin 3 and pin 1. These microphones will sputter and crackle when phantom power is applied and will work fine when you turn off the phantom power. Get the microphone repaired. 2 There is another remote powering system called A-B or T-system powering. It uses pins 2 and 3 to carry both power and audio. It is not compatible with dynamic microphones or phantom-powered microphones. 76