500 Series EQs – Shaping Frequencies in a Modular Workflow
Equalizers are among the most essential tools in audio production. In the 500 Series format, they combine precise tone shaping with the flexibility of a modular system, allowing engineers and producers to tailor their signal path to specific requirements. Control, tone shaping, and flexibility are at the heart of their role.
Whether during recording, mixing, or mastering, 500 Series EQs help structure signals, create space within a mix, and turn sonic decisions into deliberate actions directly within the analog signal path.
The question is rarely which equalizer is objectively “the best.” What matters is which module best suits the source material, workflow, musical style, and desired sonic outcome.
Today, the 500 Series format offers an enormous variety of equalizer designs. From classic API-inspired circuits and inductor-based designs to modern parametric solutions, there are specialized tools available for virtually every application in the signal chain.
At the same time, 500 Series EQs differ significantly in character, workflow, and intended use. Some modules are designed for maximum precision and transparency, while others intentionally introduce color, saturation, or the distinctive character associated with classic console designs.
One of the greatest advantages of modular systems is the ability to combine different sonic philosophies within a single rack. This allows signal paths to be tailored specifically for recording, mixing, or mastering applications.
In practice, the number of frequency bands or available features is rarely what matters most. What matters is whether an equalizer supports musical decision-making and integrates naturally into an existing workflow.
That is why you will not find a random collection of 500 Series EQs at Peakhouse Audio. Our selection is based on hands-on studio experience, direct comparisons, and modules that have proven themselves in professional recording, mixing, and mastering environments.
If you are unsure which 500 Series EQ best suits your setup, we are happy to help with equipment selection, integration, and signal-flow planning.
Less focus on frequency curves—and more focus on modules that make sonic decisions faster, more musical, and more repeatable.
AMS Neve 1073 LBEQ
AMS Neve 1073 LBEQ The AMS Neve 1073 LBEQ is a compact 500-series mono equalizer that brings the legendary EQ section of the classic Neve 1073 console module into a modern lunchbox format. Designed and manufactured in England, it uses the same discrete Class-A circuitry and inductor-based filter design as the original 1073. The module can operate as a standalone EQ in any 500-series rack or as an insert EQ when paired with the Neve 1073LB microphone preamp, creating a complete classic 1073 signal path. Sound Character The 1073 LBEQ delivers the classic Neve EQ tone with powerful low end, musical midrange and smooth high-frequency presence. Its hand-wound inductor filters reproduce the musical EQ curves that made the original 1073 one of the most sought-after studio processors in recording history. Highlights ✔ classic Neve 1073 EQ in 500-series format ✔ three-band inductor-based EQ ✔ discrete Class-A circuitry ✔ hand-wound inductors for authentic Neve tone ✔ high-pass filter (50 / 80 / 160 / 300 Hz) ✔ ±16 dB high-shelf at 12 kHz ✔ ±18 dB mid band with selectable frequencies ✔ ±16 dB low-shelf EQ ✔ EQ bypass switch ✔ signal presence and clip LED ✔ compatible with all 500-series racks
API 550A
API 550A The API 550A is a classic 3-band equalizer in API 500-series format, considered one of the most legendary analog EQ modules in recording history. Originally developed for API consoles, it is based on traditional API discrete circuitry and delivers the recognizable API sound with direct control, musicality and exceptional clarity. At the core of the 550A is the classic API 2520 op-amp design, combined with a fully discrete analog signal path. The three EQ bands offer switchable frequency points for fast and intuitive tonal shaping. A defining feature of the 550A is API’s famous proportional-Q circuit: as boost or cut increases, the bandwidth automatically narrows, resulting in highly musical yet precise EQ moves. The high and low bands also provide switchable shelving or peaking behavior, increasing tonal flexibility. Sound Character The API 550A delivers the classic musical, punchy and direct API EQ sound. Midrange remains focused and present, lows stay controlled and highs sound open and natural. Boosts especially retain a very organic character. It performs exceptionally well on vocals, drums, guitars, bass and synthesizers. Highlights ✔ 3-band equalizer in API 500-series format ✔ discrete API 2520 op-amp design ✔ classic proportional-Q circuit ✔ 7 selectable frequencies per band ✔ ±12 dB gain per band ✔ switchable shelving/peaking high and low bands ✔ fast and intuitive operation ✔ highly musical tonal shaping ✔ hard bypass ✔ ideal for recording, mixing and summing
API 550B
API 550B The API 550B is a classic 4-band equalizer in API 500-series format, widely regarded as one of the most iconic analog EQ modules in professional recording studios. It is based on the legendary API discrete circuit design and delivers the recognizable API sound with musicality, punch and exceptional clarity. At the core of the module is the classic API 2520 op-amp design, combined with a fully discrete analog signal path. The four EQ bands feature fixed selectable frequency points for fast and intuitive operation during recording and mixing. A defining feature of the API 550B is its proportional-Q circuit: as boost or cut increases, the filter automatically becomes narrower, resulting in highly musical yet precise tonal shaping. The 550B is equally suited for individual tracks and stereo bus processing and remains one of the most widely used API EQ modules. Sound Character The API 550B delivers the classic musical, punchy and direct API EQ sound. Midrange remains present and focused, lows stay tight and highs sound open and natural. Boosts especially retain a very organic musical character. It performs exceptionally well on vocals, drums, guitars, bass, synthesizers and stereo buses. Highlights ✔ 4-band equalizer in API 500-series format ✔ discrete API 2520 op-amp design ✔ classic proportional-Q circuit ✔ 7 selectable frequencies per band ✔ ±12 dB gain per band ✔ switchable high and low band filter behavior ✔ highly musical tonal shaping ✔ hard bypass ✔ ideal for recording, mixing and summing
API 560
API 560 The API 560 is a classic 10-band graphic equalizer in API 500-series format, widely regarded as one of the most iconic analog EQ modules in professional studio environments. It is based on traditional API circuitry and delivers the recognizable API sound with precision, musicality and immediate hands-on control. At the heart of the API 560 is the legendary API 2520 discrete op-amp, combined with a fully discrete analog signal path. This design provides excellent headroom, clarity and strong analog punch. Its ten fixed frequency bands allow precise control across the full audio spectrum. Each band offers ±12 dB boost and cut, making both subtle corrections and strong tonal shaping possible. The graphic layout allows very fast decision-making during recording, mixing and bus processing. Sound Character The API 560 delivers the classic precise yet musical API EQ character. Adjustments sound direct and controlled without becoming harsh. Midrange shaping is particularly effective, while lows stay tight and highs remain open and detailed. It works exceptionally well on drums, vocals, guitars, bass and stereo buses. Highlights ✔ 10-band graphic equalizer in API 500-series format ✔ discrete API 2520 op-amp design ✔ classic API graphic EQ architecture ✔ ±12 dB boost/cut per band ✔ extremely fast hands-on workflow ✔ musical shaping across the full spectrum ✔ high headroom ✔ hard bypass ✔ ideal for recording, mixing and bus processing
Chandler Limited Little Devil Equalizer
Chandler Limited Little Devil EqualizerDer Chandler Limited Little Devil Equalizer ist ein hochwertiger, vollständig diskret aufgebauter 4-Band Equalizer im 500-Series-Format, der klassische britische Konsolen-EQs der 60er und 70er Jahre in ein modernes, kompaktes Modul überträgt.Das Design orientiert sich klanglich an legendären „British Console EQs“ wie den 1071/33115-Schaltungen und kombiniert diese mit Chandler-typischer Class-A-Technik, Übertragern und induktorbasierten Filtern. Als Teil der Little-Devil-Serie wurde der EQ entwickelt, um im 500-Rack eine komplette Channelstrip-Lösung mit starkem Vintage-Charakter zu ermöglichen.KlangcharakterDer Little Devil EQ liefert einen musikalischen, warmen und druckvollen Vintage-Sound mit klarer britischer Klangästhetik.Typische Eigenschaften:kräftiges Low-End mit Substanzoffene, seidige Höhenmusikalische Mitten mit angenehmer PräsenzDie Kombination aus Shelving-Filtern und induktorbasierten Mittenbändern sorgt für eine besonders organische Klangformung, bei der selbst starke Eingriffe natürlich und „analog“ wirken. Durch die umschaltbaren Q-Faktoren der Mittenbänder kann der EQ sowohl breit musikalisch als auch fokussierter eingesetzt werden.Highlights✔ 4-Band EQ im 500-Series Format (Single Slot) ✔ inspiriert von klassischen britischen Konsolen (1071 / 33115) ✔ vollständig diskrete Class-A Transistorschaltung ✔ transformer-balanced Ein- und Ausgänge ✔ High & Low Shelf (±18 dB) bei 12 kHz sowie 50 / 110 Hz ✔ Lo-Mid & Hi-Mid parametrisch (±18 dB) mit 7 Frequenzen pro Band ✔ umschaltbare Q-Charakteristik (breit / schmal) ✔ Low-Cut Filter (47 / 82 / 150 Hz) ✔ Hardwire / True Bypass ✔ klassische Induktor- und Übertrager-TopologieTypische Anwendungen im Studio✔ Tracking-EQ mit musikalischem Charakter ✔ Vocals (Präsenz, Wärme, Air) ✔ Drums (Punch & Definition) ✔ Gitarren (Mid-Shaping & Höhenkontrolle) ✔ Bass (Low-End-Kontrolle & Gewicht) ✔ 500-Series Channelstrip-SetupsTechnische Daten✔ Gerätetyp: Mono Equalizer (500-Series Modul) ✔ Schaltung: diskret, Class-A, Transistor ✔ Bänder: 4 (High, Low, Hi-Mid, Lo-Mid) ✔ Gain: ±18 dB pro Band ✔ Frequenzen:Bass: 50 / 110 HzLo-Mid: 220 – 820 Hz (7 Schritte)Hi-Mid: 1.2 – 8.2 kHz (7 Schritte)Treble: 12 kHz ✔ Q-Faktor: umschaltbar (Mid-Bands) ✔ Filter: Low-Cut (47 / 82 / 150 Hz) ✔ THD: ca. 0.0065 % ✔ Eingangsimpedanz: 10 kΩ ✔ Ausgangsimpedanz: 600 Ω ✔ Bauform: 500 Series, Single Slot ✔ Stromversorgung: über 500-Series Rack
Cranborne Audio Carnaby 500
Cranborne Audio Carnaby 500 Carnaby 500 ist ein parametrischer 3-Band-EQ für das 500er-Format mit einem einzigartigen und revolutionären EQ-Konzept, das von Cranborne Audio entwickelt wurde. Carnaby 500 ist der weltweit erste Harmonic EQ™ - ein analoger EQ, der die harmonische Sättigung nutzt, um Frequenzanteile zu verstärken und abzusenken. Er bearbeitet Quellen, Stems und Mischungen mit echter analoger harmonischer Sättigung mit dem Gefühl, der Vertrautheit und der Kontrolle eines Equalizers. Parametrischer 3-Band-EQ und mehrDer Carnaby 500 verfügt über 3 interaktive Bänder des Harmonic EQ™, wobei jedes Band über 10 dB Boost/Cut und eigene, überlappende Frequenzregler verfügt. Jedes Band des Carnaby 500 bietet eine individuelle Obertonmischung, die auf das jeweilige Frequenzband abgestimmt ist, um maximale Musikalität zu erreichen. Das HI-Band umfasst einen Frequenzbereich von 5 kHz bis 25 kHz und nutzt eine sanfte Sättigung, um die hohen Frequenzen auf natürliche Weise über das Audioband hinaus zu erweitern und so Gesang und akustischen Instrumenten den richtigen Schliff zu geben. Das MID-Band ist ein Peak-Filter mit festem Q und einem weiten durchstimmbaren Frequenzbereich von 200 Hz bis 6,2 kHz. Es nutzt die Sättigung, um der Quelle im gesamten Frequenzbereich eine harmonische Betonung zu verleihen. Im Gegensatz zu anderen EQs hat der Carnaby 500 ein dynamisches Ansprechverhalten und erhöht die Gesamtanhebung/-absenkung und die Obertöne, wenn die Schaltkreise stärker angesteuert werden. Ein Eingangs- und Ausgangspegelregler an jedem Band ermöglicht eine Pegelanpassung von ±20 dB, so dass der Carnaby 500 mit dem Eingangsregler stärker ansteuern werden kann, um mehr Sättigungs- und Verzerrungseffekte zu erzielen, oder zurückgenommen werden kann, um bei Bedarf einen saubereren Klang zu erhalten. Stereo-Link über OPTOSYNCDas Carnaby 500 verfügt nicht nur über einen weltweit einzigartigen EQ-Schaltkreis, sondern auch über eine innovative Stereo-Link-Funktion namens OPTOSYNC, mit der zwei Carnaby 500 als perfektes Stereopaar für Mischungen und Stereoquellen arbeiten können. Robustes Industriedesign und automatische KalibrierungMit seiner robusten und außergewöhnlichen Konstruktion, den 41-fach gerasteten Potis an jedem Regler und der automatischen Kalibrierung aller analogen Sättigungswege ist der Carnaby 500 ein zeitloser Prozessor, der das Studio über Jahre hinweg bereichern wird. Hauptmerkmale 3-Band Harmonic EQ™ im 500er Format, sorgfältig entwickelt vom Cranborne Audio Team in Großbritannien Spezieller analoger EQ-Schaltkreis und einzigartige "Saturation-Core"-Technologie für harmonisch angereicherte EQ-Effekte Parametrische LO- und HI-Shelving-Bänder mit ±10 dB Cut/Boost und harmonischer Sättigung Parametrisches Peak MID-Band mit ±10 dB Cut/Boost, festem Q und harmonischer Sättigung LO-, MID- und HI-LED-Anzeigen zur Darstellung des Sättigungspegels ±20dB Eingangs- und Ausgangspegel für dichte harmonische Sättigung oder saubere EQ-Effekte Drahtloskommunikation OptoSync zwischen den Modulen für verlinkte Regler im Stereobetrieb 3,5 mm Klinkenbuchse zum Verbinden nicht-benachbarter Module Schaltkreis-Autokalibrierung für perfekte Stereoabstimmung zwischen allen Modulen True-Bypass IN/OUT über DIP-Schalter mit vollständigem oder dem Eingangstrim nachgeschalteten Modus Gerasterte Bedienelemente auf der Vorderseite für schnellen Recall und präzises Bediengefühl
Dangerous Music BAX500
Dangerous Music BAX500 The Dangerous Music BAX500 is a premium 500-Series Baxandall equalizer module that brings the sonic character of the renowned Dangerous BAX EQ into the compact 500-Series format. Designed for recording, mixing and mastering, it provides extremely musical tone shaping with minimal intervention. Instead of surgical EQ moves, the BAX500 uses broad shelving curves affecting several octaves at once, allowing subtle adjustments that open the top end, tighten the low frequencies and improve depth and clarity within a mix. The module features a DC-coupled signal path without transformers, mastering-grade components and a relay-controlled hard-bypass for accurate A/B comparisons. Sound Character The BAX500 delivers extremely musical and transparent tonal shaping. Its Baxandall shelves operate across several octaves, gently enhancing highs and lows without introducing harshness or phase issues. Instead of imposing character, it reveals clarity, depth and balance already present in the material. High-cut and low-cut filters remove unwanted extreme frequencies, improving headroom and helping mixes translate better across playback systems. Highlights ✔ 500-Series Baxandall equalizer module ✔ high and low shelving filters with ±5 dB range ✔ broad EQ curves across multiple octaves ✔ high-cut and low-cut filters (12 dB/octave) ✔ DC-coupled signal path without transformers ✔ relay-controlled hard bypass ✔ detented controls for precise recall ✔ mastering-grade components ✔ mono module – stereo operation with two units ✔ hand-built in the USA
Dangerous Music BAX500 Pair
Dangerous Music BAX500 Pair The Dangerous Music BAX500 Pair consists of two matched BAX500 500-Series equalizer modules, designed for stereo mix bus, stem processing and mastering applications. The modules bring the legendary Dangerous BAX Baxandall EQ curves into the compact 500-Series format, offering extremely musical tone shaping with minimal processing. Unlike surgical EQs, the BAX500 uses wide shelving filters that affect multiple octaves simultaneously, allowing subtle adjustments to create significant tonal improvements such as increased openness, depth and low-end solidity. When used as a stereo pair, the BAX500 becomes an ideal tool for mix-bus sweetening, mastering correction and stereo stem processing where transparency and musicality are critical. Sound Character The BAX500 is designed for extremely musical and transparent tone shaping. Its shelving curves operate across multiple octaves, opening the top end while tightening the low frequencies without introducing harshness or phase issues. Instead of imposing character, the EQ reveals clarity, depth and balance already present in the mix. Additional high-cut and low-cut filters remove unwanted extreme frequencies that consume headroom and reduce clarity, improving mix translation across different playback systems. Highlights ✔ stereo pair of Dangerous BAX500 500-Series EQ modules ✔ classic Baxandall shelving curves ✔ high and low shelves with ±5 dB gain range ✔ high-cut and low-cut filters for frequency control ✔ broad musical EQ curves across several octaves ✔ DC-coupled signal path without transformers ✔ relay-controlled hard-wired bypass ✔ detented controls for precise recall ✔ mastering-grade components ✔ hand-built in the USA
Drawmer MQ-1
Drawmer MQ-1 MQ-1 – Vintage 7-Band-Equalizer mit proportionalen Q-Kurven Der MQ-1 ist ein 1-kanaliger, parametrischer 7-Band-Equalizer, der vom legendären „Motown EQ“ inspiriert wurde. Seine proportionalen Q-Kurven erinnern an die legendären EQs, welche in den berühmten Detroit-Studios der 1960er Jahre genutzt wurden. Dieser 100 % analoge EQ verfügt über 7 Glockenkurven, die jeweils eine stufenlose Absenkung/Anhebung von ±10 dB bereitstellen und auf die wunderbar musikalischen Frequenzen des Originals eingestellt sind. Aber das ist noch nicht alles. Zusätzlich ist er mit der beliebten „CRUSH“-Funktion aus dem Drawmer 1971 ausgestattet. Diese Schaltung fügt eine angenehme harmonische Sättigung und klassische analoge Wärme hinzu – und verleiht durchlaufenden Audiosignalen damit zusätzlichen Charakter. Das Ergebnis? CRUSH macht die Bässe fetter, verleiht den Mitten mehr Präsenz und stattet die Höhen mit einem angenehmen Glanz aus. Je härter der EQ angesteuert wird, desto mehr Charakter erhält das Signal. Dieser in England entwickelte und hergestellte Verstärker liefert den klassischen warmen analogen Sound, nach dem du gesucht hast. Eigenschaften 7-Band-Equalizer mit proportionalem Q-Faktor für die 500er-Serie.Inspiriert vom Motown-EQ der 1960er-Jahre.Integrierte „CRUSH“-Funktion, die Mixes mit harmonischer Sättigung aufwärmt.Stufenlose Anhebung oder Absenkung um ±10-dBFestverdrahteter Bypass.Entwickelt und hergestellt in Großbritannien Technische Daten EQ-Frequenzen: 50 Hz, 130 Hz, 320 Hz, 800 Hz, 2 kHz, 5 kHz, 12.5 kHz, +/- 10 dB GainEingangsimpedanz: 20 kOhmMaximaler Eingangspegel: +21 dBAusgansverstärkung: +/-10 dBAusgangsimpedanz: < 100 OhmFrequenzgang: 20 Hz - 20 kHz +/-0,5 dBTHD+N: @1 kHz, Referenz 0 dBu, 0,002 %Rauschen (Referenz 0 dB): -93,5 dBAbmessungen: 1x 500er-Serie-SteckplatzGewicht: 0,38 kg
Drawmer MQ-2
Drawmer MQ-2 MQ-2 – Vintage 7-Band-Equalizer mit proportionalen Q-Kurven und Kompressor Der MQ-2 ist ein Stereo-7-Band- Equalizer, der vom legendären „Motown EQ“ inspiriert wurde. Seien proportionalen Q-Kurven erinnern an die legendären EQs, die in den berühmten Detroiter Studios in den 1960er Jahren verwendet wurden. Dieser 100 % analoge EQ verfügt über 7 Glockenkurven, die jeweils eine stufenlose Anhebung/Absenkung von ±10 dB bereitstellen und auf die wunderbar musikalischen Frequenzen des Originals eingestellt sind. Der MQ-2 ist jedoch nicht nur ein EQ. Außerdem verfügt er über einen programmabhängigen, einfach zu bedienenden One-Knob-Kompressor, der seine Hüllkurve an die Eigenschaften des Signals anpasst. Aber das ist noch nicht alles. Darüber hinaus ist der MQ-2 mit der beliebten „CRUSH“-Funktion aus dem Drawmer 1971 ausgestattet. Diese Schaltung fügt eine angenehme harmonische Sättigung und klassische analoge Wärme hinzu – und verleiht durchlaufenden Audiosignalen damit zusätzlichen Charakter. Das Ergebnis? CRUSH macht die Bässe fetter, verleiht den Mitten mehr Präsenz und stattet die Höhen mit einem angenehmen Glanz aus. Je härter der EQ angesteuert wird, desto mehr Charakter erhält das Signal. Mit unabhängigen Reglern für beide Kanäle war es noch nie so einfach, den klassischen warmen Analog-Sound zu bekommen, nach dem du gesucht hast. Eigenschaften Stereo 7-Band-Equalizer mit proportionalem Q-Faktor für die 500er-Serie.Inspiriert vom Motown-EQ der 1960er Jahre.Benötigt zwei Steckplätze der 500er-Serie.Integrierte „CRUSH“-Funktion, die Mixes mit harmonischer Sättigung aufwärmt.Stufenlose Anhebung oder Absenkung um ±10-dBOne-Knob-Kompressor zur einfachen Pegelregulierung.Beliebig tauschbare Reihenfolge von EQ und Kompressor im Signalweg.Umfassende PegelanzeigeFestverdrahteter Bypass.Entwickelt und hergestellt in Großbritannien Technische Daten EQ-Frequenzen: 50 Hz, 130 Hz, 320 Hz, 800 Hz, 2 kHz, 5 kHz, 12.5 kHz, +/- 10 dB GainEingangsimpedanz: 20 kOhmMaximaler Eingangspegel: +16 dBAusgansverstärkung: +/-14 dBAusgangsimpedanz: < 100 OhmFrequenzgang: 20 Hz - 20 kHz +/-0,5 dBTHD+N: @1 kHz, Referenz 0 dBu, 0,01 %Rauschen (Referenz 0 dB): -80 dBAbmessungen: 2x 500er-Serie Steckplätze Gewicht: 0,54 kg
Elysia xfilter 500
Elysia xfilter 500 The Elysia xfilter 500 is a high-end Class-A stereo equalizer in API 500 format, designed for professional recording, mixing, and mastering applications. As a compact module version of the xfilter, it delivers precise analog EQ processing with maximum flexibility in modern 500-series racks. Its fully discrete Class-A circuitry features true stereo linking, ensuring both channels are processed identically. This results in an exceptionally accurate and stable stereo image—ideal for bus and mastering tasks. The xfilter 500 provides four EQ bands: two parametric mid bands and flexible low and high bands. These outer bands can operate as shelving filters or be switched to resonant high- and low-pass filters. An additional passive high-frequency band (“Passive Massage”) enhances the top end with a smooth, musical character. Sound Character The xfilter 500 delivers transparent, open, and highly precise equalization with clear transient response and solid punch. The sound remains clean and detailed, making it ideal for controlled tonal shaping. Low frequencies can be tightened and defined, while high frequencies benefit from a smooth, airy enhancement through the passive LC filter. Overall, the EQ maintains a neutral and professional character suited for critical audio work. Highlights ✔ Class-A stereo equalizer in API 500 format (2 slots) ✔ 4-band EQ: low, low-mid, high-mid, high ✔ two parametric mid bands with switchable Q ✔ high and low shelf filters, switchable to resonant cut filters ✔ additional passive high-frequency band (“Passive Massage”) ✔ true stereo link for identical channel processing ✔ 41-step detented potentiometers for precise recall ✔ selected low-tolerance components ✔ excellent shielding against interference ✔ true bypass for uncolored signal path Typical Applications ✔ precise EQ during mixing ✔ stereo bus and master bus processing ✔ tonal shaping of tracks and groups ✔ tracking EQ for vocals, drums, and instruments ✔ high-end EQ in 500-series hybrid setups Technical Specifications ✔ device type: stereo equalizer ✔ circuit: discrete Class-A ✔ bands: 4 (2 parametric + high/low shelf/cut) ✔ frequency response: <10 Hz – 400 kHz (-3 dB) ✔ dynamic range: approx. 120 dB ✔ noise: approx. -98 dBu ✔ THD+N: approx. 0.0018 – 0.005 % ✔ max level: +21 dBu ✔ input impedance: 10 kΩ / output: 68 Ω ✔ format: API 500 series ✔ width: 2 slots
H2 Audio 5011
H2 Audio 5011 The H2 Audio 5011 is a 500 series EQ and a faithful recreation of the legendary Helios mic pre and EQ found on the Helios console at Olympic studios. The H2 Audio 5011 is a 3-band EQ with a unique Boost/cut low band and a high-frequency shelf fixed at 10kHz. The Mid band offers a choice of boost or cut with selectable frequencies ranging from 0.7 to 6kHz. The boost or cut is selected via a three-way toggle switch while the amount is controlled via the Mid Gain control. Furthermore, the 5011 boasts an electronically balanced input and transformer balanced output, similar to the 0011. The 5011 is a core component to the legendary British sound and has featured on countless classics from the Rolling Stones, PinkFloyd, Led Zeppelin David Bowie and many more.
Harrison Audio MR3eq
Harrison Audio MR3eq Originally developed for the Harrison MR3 studio console, the MR3eq stands out as one of Harrison's most popular EQ designs, renowned for its punchy, smooth sound, and powerful sculpting capabilities. Introduced in 1981, the Music Recording 3 (MR3) console rapidly became the preferred tool for numerous leading engineers and studios worldwide, helping to create some of the most iconic albums from the 70s and 80s. Like all Harrison production tools, the MR3 EQ delivers the vibe to inspire artists and the precision for engineers to excel. Thanks to the MR3eq module, the distinctive Harrison sound is now accessible in the 500 series format. Legacy in analog Harrison consoles have helped create some of the most highly regarded and influential music in history. Michael Jackson, ABBA, Led Zeppelin, Queen, Donald Fagan, and many more iconic artists have relied on Harrison production tools to help create their multi-platinum albums. The latest range of 500 series modules from Harrison harnesses the sound and features that engineers like Bruce Swedien, Roger Nichols, and Reinhold Mack trusted to make music that stands the test of time. MR3eq design The MR3eq is a high-performance analog EQ, crafted from decades of experience in equalizer and filter design. The circuit design of this EQ allows for precision in surgical tasks or the creation of broad musical strokes with lots of band interaction for a rich and colorful sonic character. 3-band parametric with HPF This powerful three-band parametric equalizer features Low and High-frequency 6 dB/octave Shelf bands, which can be switched to a 2nd order Bell response with Harrison’s renowned proportional Q. The Mid-band offers a continuously variable Q, while a separate High Pass Filter section includes a distinctive 3 dB resonant peak. The MR3eq’s flexible design and powerful sculpting capabilities make it a versatile tool that enhances a wide array of source materials, proving equally effective in both tracking and mixdown scenarios. Key features: The Harrison sound. Perfect for both precision EQ’ing and broad musical strokes. Three-band parametric EQ with+/- 10 dB boost/cut range. High-frequency (800 Hz –15 kHz) 6 dB/octave Shelf band, switchable to 2nd order bell. Low-frequency (40 Hz – 800 Hz) 6 dB/octave Shelf band, switchable to 2nd order bell. Mid-band (400 Hz – 8 kHz) with continuously variable, proportional Q. Separate High Pass Filter with characterful 2 dB resonant peak. Separate ‘In’ switches for EQ and HPF sections. Input overload LED Compatible with 500 Series format chassis.
Hazelrigg Industries DLC
Hazelrigg Industries DLC The Hazelrigg Industries DLC is a high-end 500-series tube inductor equalizer that combines classic analog tone with modern precision. Designed by D.W. Fearn and based on the renowned VLC / VT-5 circuitry, it is built for professional recording, mixing, and mastering environments. At its core is a vacuum tube input stage (6072A) paired with an inductor-based EQ design and a clean, low-distortion solid-state output stage. This hybrid architecture delivers vintage tube warmth while maintaining modern clarity and headroom. With hand-wound inductors, premium capacitors, and transformers on both input and output stages, the DLC provides highly musical and organic equalization. Sound Character The DLC delivers a warm, rich, and highly musical sound. Its inductor-based EQ curves are smooth and natural, making it ideal for tonal shaping. The tube stage adds harmonic depth, subtle saturation, and density while preserving detail and clarity. Compared to purely vintage designs, it retains a more open and controlled sound. A unique feature is the ability to boost and cut simultaneously, enabling complex and musical EQ curves. Highlights ✔ 500-series tube inductor equalizer ✔ vacuum tube input stage (6072A) ✔ hand-wound inductors for musical EQ curves ✔ hybrid design (tube input + solid-state output) ✔ transformers on input and output ✔ high and low boost/cut controls ✔ frequency selection switches ✔ simultaneous boost & cut capability ✔ true bypass ✔ based on D.W. Fearn designs (VT-5 / VT-2) Typical Applications ✔ musical EQ for vocals and instruments ✔ analog enhancement in mixing ✔ adding warmth to digital productions ✔ bus and master processing ✔ creative tone shaping with inductor EQ Technical Specifications ✔ device type: inductor equalizer (500 series) ✔ circuit: hybrid (tube + solid-state) ✔ tube: 6072A input stage ✔ EQ: high/low boost & cut with frequency selection ✔ dynamic range: approx. 80 dB ✔ THD+N: approx. 0.07 % ✔ frequency response: approx. 20 Hz – 20 kHz ✔ I/O: via 500-series rack ✔ format: API 500 series (single slot)
Heritage Audio 73EQ JR
Heritage Audio HA-73EQ JR The Heritage Audio HA-73EQ JR is a high-end 500-series equalizer module that recreates the legendary sound of classic 1073 EQ circuits in a compact format. Designed for professional recording, mixing, and hybrid studio workflows, it delivers classic analog tone shaping with modern flexibility. It combines a discrete Class-A signal path with Carnhill transformers and a transformer-coupled line preamp, resulting in authentic British console tone with harmonic richness, depth, and musical precision—without requiring an external preamp. Sound Character The HA-73EQ JR delivers the classic “1073 EQ sound”—warm, smooth, and musical. Its Baxandall shelving filters provide natural high-frequency clarity and powerful low-end shaping, while the inductor-based mid band adds density and presence without harshness. Even with strong EQ boosts, the sound remains stable and musical. The Class-A output stage adds subtle saturation, enhancing depth and cohesion. Highlights ✔ 3-band EQ in classic 1073 style (500-series module) ✔ discrete Class-A signal path with transformer coupling ✔ Carnhill transformers for authentic vintage tone ✔ integrated Class-A line preamp (+6 to -20 dB) ✔ high shelf: ±16 dB at 10 / 12 / 16 / 20 kHz ✔ low shelf: ±16 dB at 35 / 60 / 110 / 220 Hz ✔ mid band: ±18 dB with 6 selectable frequencies ✔ Baxandall EQ design for musical shaping ✔ EQ bypass (EQL switch) ✔ high-headroom Class-A output stage ✔ compatible with all 500-series racks Typical Applications ✔ analog EQ during mixing ✔ vocal and instrument tone shaping ✔ drum and bass processing ✔ pairing with 500-series preamps and compressors ✔ building modular analog channel strips Technical Specifications ✔ type: 500-series 3-band EQ with line preamp ✔ circuit: discrete Class A ✔ gain: +6 to -20 dB (line) ✔ EQ: 3-band inductor-based (vintage style) ✔ high shelf: 10 / 12 / 16 / 20 kHz ✔ mid band: 0.36 / 0.7 / 1.6 / 3.2 / 4.8 / 7.2 kHz ✔ low shelf: 35 / 60 / 110 / 220 Hz ✔ max output: > +26 dBu ✔ THD: < 0.025% @ 1 kHz ✔ impedance: 10 kΩ in / <75 Ω out ✔ format: 500-series module
IGS Audio Rubber Bands 500 Mastering EQ
IGS Audio Rubber Bands 500 Mastering EQ RB500ME is a stereo passive equalizer packed into a double 500-series module. This beast is equipped with transformer balanced inputs and outputs (IGS Custom) as well as a class-A driver circuit. Of course, the entire filtering section is passive and it mirrors analog equalizers from the 60s. There is a separate frequency selector for low cut and boost sections. Top quality potentiometers and ELMA switches were used to achieve outstanding performance. The first ever Stereo Pulteq-style EQ in 500 format The Rubber Bands is a wonderful tool that can add multiple levels of color to any track or mix. The best thing about, it is that you can set it up in various ways, all sounding clearly distinctive and great at the same. This is the device that gives the studio engineer an opportunity to add their own personality to the music.
M Zähl EQ1 500 Stereo-EQ
M. Zähl EQ1 500 Stereo-EQ The M. Zähl EQ1 500 Stereo-EQ is a high-end fully analog 4-band stereo equalizer in API 500 format, based on the legendary circuitry of the Zähl AM1 studio console. Designed for demanding recording, mixing, and summing applications, it delivers outstanding sound quality and flexibility in a compact module. Its discrete analog design features proportional-Q behavior, meaning the bandwidth becomes narrower as gain is increased—allowing both musical shaping and precise corrections. Each band offers multiple selectable frequencies and a gain range of ±12 dB, providing a wide range of tonal control. The EQ’s flexibility is further enhanced by switchable filter types: high and low bands can operate as shelving or bell filters, while the mid bands feature different tonal characteristics for varied sonic textures. Sound Character The EQ1 500 delivers highly musical, natural, and precise equalization. Boosts sound smooth and organic, blending seamlessly into the mix without harshness. Low frequencies can be shaped with punch and control, while the midrange offers versatile tonal sculpting—from subtle presence adjustments to corrective EQ. High frequencies remain clear and open without becoming brittle. Thanks to its varied filter characteristics, the EQ is equally suited for surgical tasks and creative sound shaping. Highlights ✔ 4-band stereo equalizer in API 500 format ✔ based on the Zähl AM1 high-end console design ✔ fully discrete analog signal path ✔ proportional-Q behavior for musical EQ response ✔ ±12 dB gain per band ✔ 7 selectable frequencies per band ✔ switchable high and low bands (shelf / bell) ✔ varied filter characteristics for tonal flexibility ✔ hard bypass for transparent signal path ✔ ideal for recording, mixing, and summing Typical Applications ✔ precise EQ for vocals and instruments ✔ shaping drums, bass, and guitars ✔ stereo bus and summing processing ✔ tracking EQ during recording ✔ versatile all-purpose EQ in 500-series racks Technical Specifications ✔ device type: stereo equalizer ✔ format: API 500 series ✔ bands: 4 fully switchable EQ bands ✔ frequency selection: 7 frequencies per band ✔ gain: ±12 dB per band ✔ filter behavior: proportional Q ✔ circuit: discrete (API 2520 op-amp based)
Mäag Audio EQ4-500
Mäag Audio EQ4-500 The Mäag Audio EQ4-500 is a single channel 6-band equalizer module that fits into a single slot of the popular 500VPR series racks. Like the EQ2, many features and the design philosophies of the Mäag Audio EQ4M standalone equalizer are incorporated into the EQ4-500 Series equalizer. Like the 1U standalone Mäag Audio EQ4M stereo mastering equalizer, the EQ4-500 has six EQ band sections divided into four, fixed frequency bell-shaped peaking equalizer sections, a 2.5 kHz shelving equalizer section, and the Air Band shelf equalizer with a choice of: off, 2.5, 5, 10, 15, 20, and 40 kHz frequencies. The five frequency bands in the main section are: Sub or 10 Hz, 40 Hz, 160 Hz, 650 Hz, and the 2.5 kHz shelf EQ. The Air Gain allows for up to +20 dB boost for the Air Band shelving equalizer. The five EQs in the main section have a boost/cut range of +15 dB and -4.5 dB with center position detent at 0 db. The EQ4-500 has both a green signal present LED at -20 dBu and a red peak LED that flashes with +23 dBu peaks. There is also an In/Out bypass switch for the entire module. The Mäag Audio EQ4-500 Series 6-Band Equalizer is the ultimate equalizer for any 500VPR rack owner that, along with the access to the Air Band, will become your first “go to” tool for both recording and mixing duties.
Mother Audio VIVID
Mother Audio VIVID VIVID, 3 band inductor based eq for 500 series, represents our attempt to reformulate the well-known classic British design, increase its spatial and sonic qualities and make it more usable for demanding tasks such as mastering applications or processing groups of acoustic instruments. In fact, any source that contains a lot of spatial details which should be preserved and not damaged, can benefit from the quality that Vivid offers. The module was designed and manufactured in Serbia, by a small group of dedicated people, including hand-wound transformers, which we are particularly proud of. The eq module contains a specially designed input transformer, wound on an unusually large core(similar to one that can be find in the bv08 , legendary U47 transformer). The result is increased headroom and a very relaxed, lush and focused sound. The entire circuit is discrete class A, and contains two custom inductors, which are also manually produced in-house. After countless tests, we decided to use tantalum capacitors for all couplings and in other critical places (9 of them actually), similar to what can be seen on old Siemens devices, and this really made an audible contribution to the overall sound impression. How does it sound?The sound is big, open, never aggressive.Vivid is extremely musical, and it is very easy to find a setting that suits any material. What can it be used on?From vocals, acoustic instruments, equalization of ambient microphones, to stereo material processing.You can use it on “djent” low tuned guitars or a live recorded choral music,doesn't matter , it will always sound great and be a useful tool. Features Circuit: Class A , discrete IN: Transformer balanced OUT: Balanced Line Driver MID band: 300 ,720 ,1k5 ,2k6 ,4k ,6k Bell +-10dB Boost-Cut HIGH band: Switchable 8kHz Shelving , 20kHz Bell +-17dB Boost-Cut LOW band: Switchable 150Hz Shelving , 60Hz Bell +-17dB Boost-Cut HPF: -3 dB on 70Hz Bypass: True Bypass Specs Maximum input level: +21 dBu Maximum output level: +21 dBu Input impedance: 10k Output Impedance: 50 Noise: <-85 dBA THD: 0.0058% at +10dBu Max. current draw: 100mA
Mother Audio WAI 2950
Mother Audio WAI 2950 WAI (wire and iron) 2950, is a 3 band, completely discrete class A inductor based, 500 series eq. In a way, we recreated the legendary w295, an eq famous for its magically beautiful “high shelf” and real vintage vibe, the secret weapon of many producers over the past decades. Input and output are balanced by our custom high class transformers. A special challenge was the output transformer, which, with the integrated LPF at 20khz is a really critical element to not lose the well-known sonic character, and the choice ultimately fell on the 50%Nickl core. Also, the impedance of the input transformer, (which in the genuine unit was relatively low) was increased to today's standards and all this resulted in an extended low freq response and a slightly “excited” sound, if we compare it with the Siemens module. The pcb board is full of NOS bsx46 Phillips transistors, and as much as possible Siemens NOS film capacitors. How does it sound?Completely magical, huge, but still focused low end and incredibly sweet highs, creamy mid range, very characteristic for an inductor based circuit.What can it be used on?Anywhere where you actually want character and sweetness. Features Circuit: Class A , discrete IN: Transformer balanced OUT: Transformer balanced MID band: 700 ,1k ,1k5 ,2k3 ,3k5 ,5.6k Bell +-8dB Boost-Cut HIGH band: 16kHz Bell , +15dB -9dB, 3dB steps Boost-Cut LOW band: 40Hz Shelf, +15dB -9dB, 3dB steps Boost-Cut HPF: -3 dB on 70Hz Bypass: True Bypass Specs Maximum input level: +21 dBu Maximum output level: +21 dBu Input impedance: 10k Output Impedance: Less than 75 Ohms Noise: <-85 dBA THD: 0.09% at +10dBu Max. current draw: 100mA
Pulse Techniques EQP-500X
Pulse Techniques EQP-500X Pulse Techniques is pleased to offer the EQP-500X 500-series equalizer, the next generation of our API 2520 gain stage passive equalizers. In the early 1970s, after condensing the classic 3U model EQP-1A into the 2U form-factor model EQP-1A3, Pulse introduced a solid-state line amp version of the EQP-1A3. These units have exactly the same front end (input transformer and passive EQ section) but utilize a solid-state opamp (genuine API 2520) gain stage driving a Triad output transformer. Many users of this version of the Pultec describe them as “more punchy” and having “a tighter low end” than the tube version. Pulse has taken this proven design to the next stage by packing them into the 500-series form factor as the EQP-500X module. These may come in a smaller package, but don’t be fooled! These EQs deliver all of the punch, mojo and sonic impact of their full-sized counterparts. SPECIFICATIONS 30, 40, 70, 100 CPS shelf boost, 0 – 13.5 dB 30, 40, 70, 100 CPS shelf attenuate, 0 – 17.5 dB 1, 2, 3, 4, 5, 8, 10, 12, 16 KCS peak boost, 0 – 18 dB; 5, 10 KCS shelf boost, 0 – 14 dB 5, 10, 20 KCS shelf attenuate, 0 – 16 dB Input Impedance: ~600 Ohms Output Impedance: ~50 Ohms Noise: Below -80 dBm Distortion: ≤ 0.15% at 10 dBm into 600 Ohms Amplifier: 20 CPS to 20 KCS; +0, -1 dB ref 1 KCS including input/output xfmrs Output Level: +21 dBm maximum
Pulse Techniques MEQ-500
Pulse Techniques MEQ-500 Pulse Techniques recently introduced a 500-series version (EQP-500X) of our popular 19″ rack-mount solid-state line amp program equalizers (EQP-1A3-SS & EQP-1S3-SS) equalizers. Based on the venerable API 2520 op-amp followed by a high-quality Triad output transformer, these are preferred by some engineers to the vacuum tube models. Before bringing the MEQ-5 midrange equalizer into the 500-series family, we discussed the project with legendary producer/engineer Jack Douglas (John Lennon, Aerosmith, Alice Cooper, Cheap Trick, etc.). Jack has indicated previously that the MEQ-5 has been a staple of his guitar, bass, vocal and keyboard sounds over the years. With Jack’s input, we made a few enhancements to the standard MEQ passive EQ section, which included the addition of 1.2k and 1.5k centers to the low-mid, addition of 1.2k and 8k to the high-mid (overlaps low-mid section and expands top-end) and some minor tweaks to the Q of the high-mid settings. We are proud to recognize Jack Douglas with the production of the MEQ-500 Jack Douglas Edition 500-series Midrange Equalizer. Just like the tube and rack-mount solid state versions, the MEQ-500JD provides exacting control of the “power region” in program material, that frequency range from about 300 Hz to 5000 Hz in which most of the sound energy is concentrated. The ear is especially sensitive to sounds in this region. In this region, even small resonances in studio acoustics and microphone and speaker responses are very evident in their effect on the listenability of the sound. Three independent sets of controls make it possible to boost on a peak curve at 200 – 1000 Hz while simultaneously boosting on a peak curve at 1.5 – 5 kHz, while simultaneously dipping at 200 – 7000 Hz. Guitars, vocals, horns, strings, keyboards, snares, toms, anything with significant midrange that requires complex contouring is a candidate for the MEQ-500JD. SPECIFICATIONS Low-midrange peak boost: 200, 300, 500, 700, 1000, 1200, 1500 CPS, 0 – 10 dB High-midrange peak boost: 1.2, 1.5, 2, 3, 4, 5, 8 KCS, 0 – 8 dB Dip Atten: 200, 300, 500, 700 CPS and 1, 1.5, 2, 3, 4, 5, 7 KCS, 0 – 10 dB Input Impedance: ~600 Ohms Output Impedance: ~50 Ohms Noise: Below -80 dBm Distortion: ≤ 0.15% at 10 dBm into 600 Ohms Amplifier: 20 CPS to 20 KCS; +0, -1 dB ref 1 KCS including input/output xfmrs Output Level: +21 dBm maximum
Rupert Neve Designs 551
Rupert Neve Designs 551 The Rupert Neve Designs 551 is a high-end 3-band inductor equalizer for the 500-Series format, combining classic Rupert Neve EQ concepts with modern analog design techniques. The EQ section is derived from the design used in the renowned Shelford Channel, adapted for modular 500-Series systems. The module features discrete Class-A gain stages, custom inductors and Rupert Neve transformers, delivering the musical tone and harmonic richness associated with classic Neve console equalizers. Designed for professional recording and mixing environments, the 551 offers precise tonal shaping and analog character within a compact modular format. Sound Character The 551 provides a musical analog EQ tone with powerful low-end, clear midrange and open high frequencies. Its inductor-based design introduces subtle harmonic saturation, allowing both gentle tonal shaping and more pronounced EQ boosts without harshness. The midrange section, inspired by classic Neve console circuits, is particularly effective for enhancing vocal presence and shaping instruments within a mix. Highlights ✔ 3-band inductor EQ in 500-Series format ✔ based on the Shelford Channel EQ design ✔ discrete Class-A circuitry ✔ custom Rupert Neve input and output transformers ✔ low band: ±15 dB at 35 / 60 / 100 / 220 Hz ✔ mid band: ±15 dB with 6 selectable frequencies ✔ high band: ±15 dB at 8 kHz or 16 kHz ✔ switchable shelf or peak curves ✔ mid Hi-Q switch for tighter filtering ✔ 80 Hz high-pass filter ✔ EQ bypass switch ✔ compatible with all 500-Series racks
SSL 500 UltraViolet EQ
Solid State Logic SSL 500 UltraViolet EQ The Solid State Logic SSL 500 UltraViolet EQ is a high-end stereo equalizer in API 500 format, combining classic SSL tone with modern flexibility. It is partly derived from the “Violet EQ” section of the SSL Fusion and enhanced with additional parametric mid bands for precise tonal control. Designed as a 4-band stereo EQ, it is especially suited for mix bus and mastering applications. The combination of musical shelving filters and precise mid bands allows both subtle enhancement and surgical correction. A key feature is the Focus mode, which increases Q and gain range, enabling highly precise frequency shaping. Sound Character The UltraViolet EQ delivers a clean, open, and highly detailed sound, typical of modern SSL processing. At the same time, it remains musical and flexible. The shelving bands provide broad tonal shaping, while the parametric mids with Focus mode allow for precise corrective EQ work. It excels on mix bus applications, offering clarity, definition, and controlled low-end response. Highlights ✔ 4-band stereo EQ in API 500 format ✔ based on SSL Fusion “Violet EQ” concept ✔ high & low shelving filters (minimum-phase design) ✔ 2 fully parametric mid bands ✔ Focus mode for extended precision (up to ±18 dB) ✔ switchable high-pass filter (30 / 40 / 50 Hz) ✔ output trim control ✔ ideal for mix bus and mastering ✔ combines musical and surgical EQ capabilities Typical Applications ✔ mix bus and mastering EQ ✔ subgroup processing (drums, vocals, instruments) ✔ surgical frequency correction ✔ analog enhancement of digital mixes ✔ pairing with SSL Bus Compressor Technical Specifications ✔ device type: stereo equalizer ✔ format: API 500 series (dual slot) ✔ EQ: 4-band (HF shelf, LF shelf, 2 parametric mids) ✔ gain: ±9 dB (±18 dB in Focus mode) ✔ frequency ranges: – LF: 30 / 50 / 70 / 90 Hz – HF: 8 / 12 / 16 / 20 kHz – LMF: 100 Hz – 1.1 kHz – HMF: 400 Hz – 6 kHz ✔ high-pass: 30 / 40 / 50 Hz ✔ output trim: ±12 dB ✔ processing: analog