Rupert Neve 551 - 500 Series Inductor EQ - Manual (Page 5)

8K /16K
With the switch out, the center or corner frequency of the high band is 8 kHz. With
the button pressed, the center or corner frequency changes to 16 kHz. Between this
switch and the HI PEAK switch, you have 4 different EQ curves to finesse the high
frequency content.
HI PEAK
When the button is out, the high frequency band operates in shelf mode, boosting or
cutting above the corner frequency at approximately 6 dB/octave. Below the corner
frequency the amount of boost or cut gradually diminishes. With the HI PEAK button
pressed, the high frequency band changes to peak mode with a bell shaped boost
or cut curve. The Peak mode utilizes an inductor and capacitor circuit to create the
bell-shaped curve.
MID FREQ
The MID FREQ rotary switch has 6 positions to select the center frequency of the
mid band EQ stage. This circuit utilizes an inductor and capacitors to shape the EQ
curve, the same way as Rupert Neve’s console designs of the 70’s. The frequencies
chosen are 200 Hz, 350 Hz, 700 Hz, 1.5kHz, 3 kHz and 6 kHz. 200 Hz is
especially useful for cuts on individual tracks within a dense mix.
MID HI Q
The resonance or Q of the mid band at maximum boost is typically 2 when the
button is out. When the MID HI Q is pressed at maximum boost, the Q narrows
to approximately 3.5. The Q widens nicely with less boost or cut as is typical for
passive EQ circuits. The Q tends to be slightly wider when the frequency is set lower,
and slightly higher for higher frequency selections. The Q is also narrower for cuts
than it is for boosts and the mid band is non-symmetrical by design.
MID LEVEL
Adjusts up to 15 dB of boost or cut at the selected mid frequencies. Remember to
reduce the signal level at the source to minimize the potential for distortion when
any of the 3 bands are boosted significantly.
HPF
Engages an 12dB per octave High Pass Filter set to 80Hz
LOW FREQ
The LOW FREQ rotary switch has 4 positions for selecting one of four corner or
center frequencies for the low band EQ section. The frequencies are 35 Hz, 60 Hz,
100 Hz and 220 Hz.
LO PEAK
When the button is out, the low frequency band operates in shelf mode, boosting
or cutting below the corner frequency. Above the corner frequency the amount of
boost or cut gradually diminishes at approximately 6 dB/octave. With the HI PEAK
button pressed the low frequency band changes to peak mode with a bell shaped
boost or cut curve.