Rupert Neve 551 - 500 Series Inductor EQ - Manual (Page 4)

551 Design Notes
Featuring 3 bands of EQ inspired by Mr. Neve’s most prized vintage designs, along
with custom transformers and class-A gain blocks, the 551 brings the thick, powerful
lows and sweet highs of Rupert’s classic EQs to the 500-Series format.
The 551 echoes the simple and definitive Rupert’s classic 3-band EQ feature-set,
with a custom inductor, switched frequencies and a HPF. Traditional transformer
coupled inputs and outputs designed specifically for the 500 series are used for both
technical performance reasons and optimum musical reproduction.
The 3-band, custom-tapped inductor EQ on the 551 was inspired by RND’s favorite
portions of Rupert’s vintage EQ designs. The low frequency band is designed to
produce a creamy, resonant bass response. Additionally, the LF band on the 551
can be used as either a shelf or a peak filter, adding punch, dimension, and immense
control to your low end. The 551’s inductor midrange band is also based off of his
classic EQs, which are ideal for sweetening vocals and instruments while bringing
them forward in a mix. Additionally, the mid frequency band’s proportional “Q”
response makes it well-suited for minimizing problematic frequencies in a source.
The 551’s high frequency band is a hybrid vintage / modern design, blending
inductor circuitry with capacitor-based topologies to achieve the vintage tones with
enhanced control. The High Pass filter is a 12dB/octave design with a fixed 80Hz
frequency. As Rupert originally intended with his most prized classic designs, each
EQ section uses low-feedback, class-A discrete electronics to prevent low-level
artifacts and harshness from detracting from the tonal shaping. The EQ circuit itself,
however, is a decidedly modern updated design using techniques and components
that were simply not available 35 years ago, and should not be considered a
“clone”.
Both the high and low band can be switched from shelf to peak curves and offer 15
dB of boost or cut. The high band can be switched from 8 kHz to 16 kHz, and the
low band can be selected at 35 Hz, 60 Hz, 100 Hz or 220 Hz. The inductor based
Mid Band offers 6 center frequencies; 200 Hz, 350 Hz, 700 Hz, 1.5 kHz, 3 kHz
and 6 kHz. The Mid Band also has a “Mid Hi Q” switch to narrow the bandwidth
(increase the Q) of the filter.
Power and audio connectivity can be supplied through any 500 series compatible
rack.
551 Features
EQ IN
Engages all bands of the equalizer except the hpf.
HF
Adjusts up to 15 dB of boost or cut at selected high frequencies.