Digitally Controlled
Analog Equalizer

1.1 What the W5091R is

The W5091R is a four-channel digitally controlled analog equalizer for professional studio use. It combines a classic analog equalizer signal path with a modern control surface, grouped channel operation, recallable presets and fast A/B/C comparison. The audio path remains analog; digital control provides repeatable settings, memories and efficient operation.

The front panel is organised around the way engineers actually work: select a channel or group, remove unwanted extremes with the high-pass and low-pass filters, shape the source with three musical bandpass sections, and compare the complete result using memory banks and bypass. Factory presets provide practical starting points for mastering, mixing and tracking, while user memories allow preferred settings to be adapted and retained.

1.2 Background: the built-in Neumann W5091 module

At the heart of the W5091R are original Neumann W5091 equalizer modules from the Neumann N5000 console system. The W5091 was designed as a four-channel audio-processing module. Each channel contains a high-pass filter, a low-pass filter and three active bell-type equalizer sections with selectable frequency, bandwidth and gain.

The original Neumann concept was already digitally controlled and analog in the audio path. The W5091R builds on that idea and presents it as a modern rack unit with practical channel grouping, live memory banks and studio-friendly comparison functions.

1.3 Where this unit shines

• Recallable analog tone shaping on stereo buses, stems and inserts.
• Fast comparison between three EQ ideas using banks A, B and C.
• Four-channel operation for two stereo pairs, four mono channels or grouped multi-channel work.
• Broad, musical equalization using one-octave or three-octave bandwidth choices.
• A total of 24 presets: 16 protected factory starting points plus 8 user slots.
• Workflows where the engineer wants analog character with repeatable settings and clear visual feedback.

1.4 Signal and control philosophy

The W5091R separates audio and control. The audio remains analog, while the front panel selects electronic settings. Editing always follows the selected channel or channel group.

The selected memory bank A, B or C is always live. Changes are written directly to the active bank. There is no separate Store command. A long press on another bank copies the current settings to that bank and switches to it, making comparison quick and natural.

2.1 Start with a channel

Picture the W5091R patched across a vocal, bass, drum bus or stereo mix. You first choose the channel you want to hear. If you are working in stereo, select one side and add the other side to the group. From that moment, the unit behaves as if the two channels are one equalizer: every move is mirrored across the group.

2.2 Clean up before you shape

The first useful move is often not boost, but removal. Engage the high-pass filter to clear unwanted low-end energy, or use the low-pass filter to remove top-end noise. The cut filters are the studio equivalent of clearing the workbench before placing the important tools on it.

2.3 Shape with three musical bands

The three bandpass sections become the creative core. Select a band, choose its frequency with the encoder, set gain, and choose a broad or narrower bandwidth. A three-octave setting is useful when the source should feel warmer, clearer or more open. A one-octave setting is useful when a more specific area needs attention.

The displays show the selected EQ curve and parameter boxes, so the control surface remains easy to read during listening. The workflow is adjust, compare, refine and trust your ears.

2.4 Compare ideas with A, B and C

Banks A, B and C are live working memories. While bank A is selected, your moves become bank A. While bank B is selected, your moves become bank B. To copy an idea, long-press another memory bank. The current settings are copied to that bank and the unit switches to it. You can then change the copy and compare without rebuilding the starting point.

2.5 Trust your decisions

Good EQ decisions are made by comparison. Long-press the active A, B or C bank for temporary linear, long-press a band’s LIN key to temporarily reverse that band’s on/linear state, press SHIFT and then long-press LIN to solo one bell band, press SHIFT and then long-press IN to solo the complete bandpass section while HP and LP are temporarily excluded, or long-press IN without SHIFT to solo the currently active HP and LP filters while held; inactive filters remain off. Use BYPASS ALL for the complete-unit comparison. The goal is to make the best setting easy to find and easy to verify.

When comparing A, B and C banks, preset auditions, temporary linear states or bypass conditions, try to compare at similar perceived loudness. A slightly louder result can appear better even when the tonal decision itself is less useful, so loudness-matched listening leads to more reliable choices.

3.1 Front panel map

The front panel is organised into seven working areas: keypad, high-pass filter, three bandpass sections, low-pass filter and global controls. The configuration menu is separate from normal EQ operation and is designed for setup, diagnostics and system information.

3.2 Keypad and channel selection

The keypad selects one channel or a grouped set of channels. All editing applies to the selected channel or channel group.

3.3 Memory banks A, B and C

The W5091R has three memory banks per channel or channel group: A, B and C. The selected memory is always the active working memory. Changes are stored directly in the selected bank; there is no separate Store action.

3.4 Preset library

The W5091R preset library is separate from the three live A/B/C working memories and contains 24 presets in total: 16 protected factory presets grouped under Mastering, Mixing and Tracking, plus 8 user slots for your own starting points. First select the channel or channel group and the memory bank that should receive or provide the settings. Make sure that no temporary memory override is active, press Shift, then briefly press that same, already selected memory key (A, B or C). The preset menu opens with the selected bank as its context; using Shift with a different memory key does not open preset mode.

Factory presets and the Load function for user presets are auditioned before they are stored. Select a preset and press the third encoder: the preset is applied temporarily to the selected channel or group while OLED 2 shows AUDITION ACTIVE and memory unchanged. Auditioning and loading automatically force the selected channel or channel group into circuit (IN). BYPASS ALL remains the only override, so switch it off before auditioning. Choose to return if you want to restore the original bank settings and continue browsing, or continue with loading to open the final confirmation. Confirming the load keeps the auditioned preset in the active bank and closes preset mode; returning from the final confirmation restores the original bank settings. User Store and Clear actions do not use auditioning and retain their normal confirmation step.

3.5 High-pass and low-pass filters

The high-pass and low-pass filters use the same control logic: a display shows the selected corner frequency, an up/down button selects the frequency, and a filter on/off button toggles the filter between linear and the selected corner frequency.

3.6 Bandpass filters 1, 2 and 3

Each bandpass filter has frequency, gain and Q-factor control. The bands are partially overlapping, making it possible to shape musical areas rather than isolated frequency points only.

3.7 Global controls

Global controls affect the complete selected operating context. They are intended for quick verification, safe comparison and system-level decisions without changing detailed band settings.

3.8 Temporary listen functions

Temporary listening functions help you isolate the contribution of individual EQ sections without changing the stored settings. Most remain active only while the final key is held; temporary linear is the exception and remains active until a memory key is pressed.

Temporary linear: long-press the currently active A, B or C memory key. The selected channel or group is heard with its EQ filters set linear. The function remains active after the key is released, the previously active memory LED flashes slowly, and pressing any memory key leaves temporary linear and restores normal memory operation.

Band solo: press SHIFT, then long-press the selected band’s LIN key. The selected bell band is isolated while LIN is held. SHIFT is a sequential prefix: its LED flashes until LIN is pressed, so the two keys do not need to be held at the same time.

Temporary LIN audition: long-press a band’s LIN key without SHIFT to temporarily reverse that band’s current state. If the band is on, it is made linear while LIN is held. If the band is already linear, it is temporarily switched on while LIN is held. Releasing LIN restores the previous state.

BP solo: press SHIFT, then long-press IN to solo the complete bandpass section while HP and LP are temporarily excluded. Releasing IN restores the previous state.

HP / LP solo: long-press IN without first pressing SHIFT. Any HP or LP filter that is already active is soloed while IN is held. Inactive HP and LP filters remain off. Releasing IN restores normal operation.

Band flip: long-press the selected band’s Q key. The band’s gain is inverted while Q is held, so a boost becomes a cut and a cut becomes a boost. The encoder remains active, allowing you to sweep frequency and hear where the band affects the content.

Global bypass: long-press BYPASS ALL for a temporary unit-wide comparison. Release it to return immediately to the previous state.

For all listening checks, compare at approximately the same perceived loudness. Louder settings often seem more impressive, so matching level as closely as possible leads to more trustworthy EQ decisions.

3.9 Firmware update

To enter firmware-update mode, long-press the POWER button while switching the unit on using the rear IEC inlet switch. The POWER-button LED indicates the update state.

• Purple: the unit is waiting for a firmware update.
• Lime, steady: the update has been accepted.
• Lime, fading off–on: firmware transfer is in progress.
• Yellow: the update has been rejected because the signature is invalid or the firmware version does not correspond with the hardware configuration.

4.1 Rack mounting and cooling

Mount the W5091R in a standard 19-inch rack. The unit occupies 2U and uses natural cooling. Leave sufficient ventilation space and avoid placing the unit directly above equipment that produces excessive heat.

• Use all appropriate rack screws and support the rear in mobile racks.
• Do not block ventilation paths.
• Allow the unit to stabilise before critical measurement or mastering work.

4.2 Power connection

Connect the IEC mains inlet to a correctly rated mains outlet. Use the rear-panel mains switch as the primary power isolation point when installing or changing connections. Do not open the unit unless qualified to work on mains-powered audio equipment.

4.3 Audio connections

Use balanced XLR connections for professional studio integration. Keep input and output cabling clearly separated from mains wiring and high-current digital wiring where possible.

4.4 Grounding, hum and cabling

Keep audio cabling away from mains transformers, power supplies, LED dimmers and high-current digital cables. If low-frequency hum or narrow peaks appear in measurement, first check grounding, cable routing and whether unused inputs are properly terminated.

• Use balanced audio connections wherever possible.
• Avoid unnecessary ground loops between computer, converter, patchbay and rack.
• Keep USB and control cables physically separated from sensitive analog input wiring.
• When measuring noise, terminate unused inputs at the source impedance used in the studio.

4.5 First power-up check

1. Set all connected monitor paths to a safe low level.
2. Power the unit and wait until the power LED indicates ready.
3. Select one channel and confirm that IN and BYPASS ALL operate as expected.
4. Check that each filter can be set to LIN before applying gain.
5. Pass a known signal through each channel and confirm level, polarity and channel routing.

5.1 Recallable stereo mix EQ

Select channels 1 and 2 as a stereo group. Before starting from linear, audition the Mixing presets: Tight, Punchy, Smooth and Spacious. They provide contrasting starting points for a stereo mix or bus. Load the closest direction into the active bank, then refine BP1 for weight, BP2 for midrange balance and BP3 for presence or air. Keep bank A as the selected starting idea, long-press B to copy A to B, then make a brighter, leaner or otherwise adjusted version for comparison.

5.2 Dual-stereo mastering comparison

Use channels 1–2 for one stereo chain and 3–4 for a second stereo chain. The Mastering presets — Open, Warm, Defined and Air — can be auditioned as four different tonal starting points. For example, audition one direction on channels 1–2 and another on channels 3–4, then load the preferred starting point and use A, B and C for smaller variations. Fine gain is especially useful for subtle mastering-style moves after the broad direction has been chosen.

5.3 Drum bus weight and focus

On a drum bus, the Mixing presets Tight and Punchy are useful whole-bus starting points. The Tracking presets Kick Punch, Snare Crack, Tom Weight and Hi-hat Sheen can also be auditioned as tonal references when exploring particular parts of the drum spectrum; they are not intended to be fixed recipes for the complete bus. After choosing a direction, BP1 can add or remove weight, BP2 can manage boxiness or punch, and BP3 can shape attack and cymbal detail. Press SHIFT, then long-press LIN to hear what each band contributes before deciding whether it helps the groove.

5.4 Vocal or instrument tracking chain

Insert one channel on a vocal, bass, guitar, piano, keyboard or synthesizer chain. The Tracking presets provide source-oriented starting points: Vocal Clarity for vocals, Bass Definition for bass, EGTR Focus for electric guitar and Piano Clarity for piano or keys. Drum-oriented Tracking presets are available for kick, snare, tom and hi-hat. There is no dedicated synthesizer preset, so use the closest tonal starting point or begin from linear. After auditioning and loading, refine the high-pass filter, gain, frequency and Q to suit the actual source, and use B or C for creative alternatives.

5.5 Four-channel console insert workflow

Use the four channels across four mono sources or two stereo pairs. Each mono channel can start from a different Tracking preset, while a linked stereo pair can audition one of the Mixing presets. For example, one channel can start from Vocal Clarity, another from Bass Definition, while channels 3–4 operate as a stereo group using Spacious or another Mixing preset. Channel grouping makes it possible to edit related channels together while still allowing individual channels to be selected for correction.

5.6 Audition before loading

Tip: factory presets can be auditioned from preset mode before they are loaded. Use auditioning to explore different tonal directions while the active A/B/C memory remains unchanged. Load only the preset that provides a useful starting point, then adapt and compare it in the normal working memories.

6.1 Mechanical and rear panel

2U 19-inch rack format. Rear-panel connections include balanced audio I/O, mains inlet and control/service connectivity depending on product configuration.

6.2 Equalizer and filter ranges

Each channel provides a high-pass filter, low-pass filter and three musical bell-type equalizer bands. Band ranges follow the Neumann W5091 concept and are intended for broad tonal shaping rather than surgical equalization.

6.3 Neumann W5091 module reference data

The original Neumann W5091 module documentation specifies four balanced floating inputs, four balanced non-floating outputs, a maximum input/output level of +22 dBu, a high-pass range of 80–480 Hz, a low-pass range of 5–12.5 kHz and a 12 dB/octave cut-filter slope. These figures describe the original module and should be verified at complete-product level for the W5091R production unit.

6.4 Audio performance (measured)

The values below are typical measured results from the reference W5091R unit. Where numeric results differed between channel pairs 1–2 and 3–4, the listed value is the arithmetic mean of the two pair measurements. Analog component and module tolerances can cause small differences between channels and production units, so these figures are indicative measured performance rather than guaranteed limits.

Mastering preset performance

The four protected Mastering presets were also measured at the nominal 0 dB reference level (+6 dBu). The values below show the measured signal-to-noise ratio over 20 Hz–20 kHz together with THD at 1 kHz. See the Mastering factory preset curves further below in the manual.

Measurements were made using a QuantAsylum QA403 professional audio analyser. The W5091R nominal level of 0 dB corresponds to +6 dBu at the balanced inputs and outputs. The measured bypass noise floor of −109 dBu is close to the practical measurement limit of the QA403 in this setup, so this figure should be regarded as an approximate measured value. For crosstalk, both channel-pair measurements were below the same limits, so the common measured limit is shown rather than averaging inequality values.