Rupert Neve 511 - 500 Series Mic Pre with Silk - Manual (Page 7)

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1. Tsutomu Oohashi, Emi Nishina, Norie Kawai, Yoshitaka Fuwamoto, and Hishi Imai.
National
Institute of Multimedia Education, Tokyo. “High Frequency Sound Above the Audible
Range,Affects Brain Electric Activity and Sound Perception” Paper read at 91st. Convention of
the A.E.S.October 1991. Section 7. (1), Conclusion.
2. Miland Kunchur,Depart of Physics and Astronomy, University of South Carolina. “Temporal
resolution of hearing probed by bandwidth restriction”, M. N. Kunchur, Acta Acustica united
with Acustica 94, 594–603 (2008) (http://www.physics.sc.edu/kunchur/Acoustics-papers.
htm)
3. Miland Kunchur,Depart of Physics and Astronomy, University of South Carolina.Probing the
temporal resolution and bandwidth of human hearing , M. N. Kunchur, Proc. of Meetings on
Acoustics (POMA) 2, 050006 (2008)
511 FEATURES
MICROPHONE INPUT
The microphone input is balanced but not floating, being a variant of an instrumen-
tation amplifier. Our well-proven “Transformer-Like-Amplifier” (T.L.A.) configura-
tion is used, which includes an accurate toroidal Common Mode Low Pass Filter
that rejects Common Mode signals and excludes frequencies above 150 kHz.
(There are high powered broadcast transmitters at and above this frequency in
several continents and, even if you can’t hear them, any vestigial intermodulation
products must be excluded!)
When the Mic Gain switch is set to Unity (0 dB), the Portico 511 microphone
pre-amplifier can handle a balanced input signal of more than +20 dBu without an
input attenuator pad! This is a unique feature that enables this input to double as a
line input.
THE LINE OUTPUTS
The main output signal comes from the output transformer secondary which is
balanced and ground free. A ground free connection guarantees freedom from
hum and radio frequency interference when connected to a balanced destination
such as the input to another Portico module or a high quality ADC. However
the transformer may be used with one leg grounded without any change in
performance. It is not necessary to “ground” one leg at the Portico output. It
would normally get a ground connection when fed to equipment that is not
balanced. Maximum output level is more than +20 dBu, which provides a large
margin over and above the likely maximum requirement of any destination
equipment to which the 511 is connected.
MIC GAIN
A 12-way precision rotary switch controls gain from 0 to 66 dB in 6 dB steps.
TRIM
Continuously variable +/-6 dB level control.