500 Series Compressors

The SSL Bus Comp Classic brings the legendary stereo bus compressor of SSL consoles to a 19" / 1U rack unit. Built on the authentic circuit with THAT 2181 VCAs, it delivers the signature "glue" that binds a mix, makes drums punch and gives the master a solid sound.

Legendary Harrison-Character Compressor in 500-Series FormatThe Harrison Audio Comp 500 Series Compressor brings the iconic tonal finesse of Harrison’s studio legacy into a compact, powerful 500-series module. Built around a classic feed-forward architecture and featuring a THAT 2180 VCA chip, it delivers smooth, musical dynamic control—from subtle, transparent leveling to colorful, saturated compression—making it the “secret sauce” you’ll reach for on vocals, guitars, drums, and beyond.Key Features:Classic feed-forward VCA design with THAT 2180 chip for rich analog performanceProgram-dependent Attack that automatically adapts to the input signalContinuously variable Release control ranging from fast to slow for expressive dynamics shapingVersatile range from transparent leveling (e.g., 1:2 ratio with fast release) to vibe-heavy compressionInput overload LED for precise gain stagingSlim, rugged 500-Series module—perfect for lunchbox racks or studio racks

Glueing mixes together for 40+ yearsThe legendary sound of the SSL Stereo Bus Compressor has been glueing mixes together for 40+ years. Often imitated but never equaled, the centre section compressor from the 1980's Solid State Logic G-Series analogue console is an audio production legend. It is a simple unit with a simple purpose; it makes complete mixes sound bigger, with more power, punch and drive.FeaturesLegendary SSL G Series Stereo Bus CompressorTHE glue and punch makerAdditional compression ratio settings 1.5 / 3 / 10Renowned ‘Auto’ releaseHPF in sidechain switchable to 30Hz / 60Hz / 106Hz / 125Hz / 185HzSidechain In / Out switchTurns a mix into a recordThe Stereo Bus Compressor brings cohesion and strength to your mix unlike any other processor. To this day it remains a key element of the SSL sound and has become not just a tool for production but a part of top engineers and producers creative process.  

Legendary sonic signature of the SL 4000EThe new E Series Dynamics Module for 500 Series racks reproduces the legendary sonic signature of an early 80's classic, the SL 4000 E console channel strip, which was featured on countless 1980's recordings. The E Series Dynamics Module features a compressor/limiter and an expander/gate, both of which return faithfully to the circuitry and key components which define the sound of the original SL 611E Series channel strip.FeaturesImmortal SSL 4000 Series circuitryClass A VCA replicationExpander/GateBased on classic 611E console channel stripChannel compression in 500 seriesA true RMS converter is used in the side chain while the gain element is an all discrete design identical to the Class A VCA chip used in the original unit. The compressor contains additional switching options to defeat the over-easy curve and to use a linear release instead of the more usual logarithmic curve. The result is a compressor with three distinct voices, each with its own musical character.

Deceptively simply, extremely effective SiX Channel Strip (SiX CH) is a single-width 500 Series channel strip using the SuperAnalogueTM channel processing features from SSL’s SiX console including the Mic-pre, low and high frequency EQ, as well as the single knob compressor.FeaturesSSL SuperAnalogueTM  mic pre+48V phantom powerPhase invert switch5 segment LED meter in dBuSwitched 12 dB/oct, 75 Hz High Pass Filter (HPF)Classic SSL HF and LF EQSwitch from shelf to bell curveSingle knob Channel Compressor with variable Threshold.Front Panel TRS Line Input with 1MΩ Hi-Z switch.SuperAnalogue Using the same technology as SiX and large-format SSL consoles, SiX CH features a SuperAnalogueTM mic pre, offering wide gain range and ultra-low noise. It’s clean, fast and punchy - the perfect preamplifier for any source material.SSL HF and LF EQSiX CH EQ is a classic SSL style gentle, broad stroke two-band design with high and low shelving filters at 3.5 kHz and 60 Hz, +/-15 dB gain range. Each band can be independently switched between shelving and bell curves. The bell curves change centre frequency to operate at 5 kHz and 200 Hz giving greater versatility from the two controls.Channel compressor A ‘one knob’ channel compressor with features that give powerful and versatile performance from its deceptively simple controls. Using the tried and tested SSL feed-forward circuit design, program-dependant attack time and automatic make-up gain to maintain signal level.TRS Line Input The front facing TRS line input offers a convenient way to add instruments on the fly or use SiX CH as a feature packed summing module. 10 kΩ nominal Line Input impedance can be changed to 1 MΩ via the Hi-Z switch. The 1MΩ impedance makes this input suitable for very high impedance sources such as passive guitar pickups without the need for an external DI box.

Transient Designer Module The Transient Designer TDx brings level-independent dynamics processing to the world of the 500 Series. On/Bypass With On/Bypass you switch the module on or off (bypass). Signal LED The Sig LED (Sig) indicates whether an audio signal is present at the input and exceeds a level of -20 dB. This LED indicator is used as an aid to quickly identify whether a signal is arriving at the TDx in a complex studio cabling system. Attack Attack can be used to boost or cut the transient phase of a signal by up to 15 dB. Positive attack increases the amplitude of the transient response. Negative attack attenuates the amplitude of the transient response. Sustain With Sustain you can lengthen or shorten the decay phase of a signal by up to 24 dB. Positive Sustain extends the decay. Negative Sustain shortens the decay. Mix The mix control allows for continuous crossfade aka parallel mix between processed (WET) and unprocessed (DRY) signals. Output With the output control the output gain can be attenuated in order to optimally drive subsequent devices. The Differential Envelope Technology Our Differential Envelope Technology (DET) allows dynamic signal characteristics to be processed by forming the difference between envelopes and thereby making them level-independent. The envelope trackers align the working processes with the natural signal characteristics. This ensures optimum results for every moment.  Specifications:  Input & Output: balanced Maximum input & output gain: 21 dBu Input impedance: 20 kΩ Output impedance: 150 Ω Common mode rejection: > 82 dB Frequency range (-3 dB): 10 Hz – 100 kHz THD & N (0 dBu, 10 Hz – 22 kHz): 0.03 % Noise (A-weighted): -92.3 dB Dynamic range: 113 dB Dimensions & Weight Unit weight: 0.65 kg Shipping weight (incl. packaging): 0.9 kg

Dual-Band De-Esser Module Our well known De-Esser as a dual-band version built into a single module for the 500 Series. On/Bypass With On/Bypass you switch the module on or off (bypass). Signal LED The Sig LED (Sig) indicates whether an audio signal is present at the input and exceeds a level of -20 dB. This LED indicator serves as an aid to quickly recognize whether a signal is arriving at the DeS in a complex studio cabling system. Hi-S The Hi-S control adjusts the intensity of the S sound reduction in the upper frequency band. The center frequency for sibilance detection is 11.2 kHz with a bandwidth of 3 kHz. Lo-S The Lo-S control adjusts the intensity of the S sound reduction in the lower frequency band. Male/Female Voicing The Voice switch is used to adjust the low-band de-esser to the voice characteristics. The switch changes the center frequency for the sibilance identification: Female: 7.6 kHz, Male: 6.4 kHz. The processing bandwidth in the low band is 1.44 kHz. De-Esser Tech Talk De-Essing by Phase Cancellation SPL has developed a circuit technology that combines efficient de-essing with maximum ease of use. De-essing already during recording spares a lot of time in comparison to the subsequent search for the S-sounds in post production. The DeS automatically adjusts itself to the relevant frequencies and hones in on them so that only the range of the S-sound is processed and neighbouring frequencies remain untouched. This range is phase-inverted and mixed back into the original signal, which acoustically deletes the S-sound. The DeS therefore works unobstrusively and sound-neutral. Auto-Threshold The DeS features our Auto-Threshold which automatically adjusts the threshold if the input level fluctuates due to varying distance to the microphone which leads to fluctuating input levels. With Auto-Threshold engaged, the de-essing intensity remains constant at the value you set – a great help not only for untrained speakers/singers in the studio and live. With conventional de-essers using compressor technology, the processing intensity decreases as the distance to the microphone increases to which compressors or limiters then react by letting the S sounds reappear. The disadvantage of weaker de-essing – bad enough in itself – therefore also leads to undesired effects in the subsequent processing. Auto-Threshold prevents these disadvantages from occurring in the first place. Specifications: Input & Output: balanced Maximum input & output gain: 21 dBu Input impedance: 20 kΩ Output impedance: 150 Ω Common mode rejection: -82 dB Frequency range (-3 dB): 10 Hz – 100 kHz THD & N (0 dBu, 10 Hz – 22 kHz): 0,03 % Noise (A-weighted): -92.3 dB Dynamic range: 113 dB Dimensions & Weight Unit weight: 0.65 kg Shipping weight (incl. packaging): 0.9 kg

The Heritage Audio 2264E compressor limiter is a diode bridge based dynamics module, engineered to be used in the restoration process of vintage 80 Series consoles. It can also be installed in the Heritage Audio Frame 8 and Rack 2, where there is provision for linking up to 8 units in 2 different buses. It is fully Class A, including the same output stage found in the HA1073, which reacts in a much nicer way to compression than class A/B amplifiers. It is completely handmade and wired in the same fashion as the rest of the Heritage Audio 80 Series modules. Specifications: Line input impedance: 10KOhms bridging, transformer balanced and floating. Output impedance: Less than 75 Ohms, transformer balanced and floating, 600 Ohms terminated. Maximum output: Greater than +26dBu, 600 Ohms terminated. THD: Less than 0.025% at 1Khz, Less than 0.05% at 100Hz, at no gain reduction. Frequency response : 20Hz (+0.3dB) to 20Khz (-0.2dB). Maximum Gain: 20dB. Maximum Power consumption: Less than 120 mA @+24VDC.

Discrete Compressor, Re-Issue. Originally released in the 70's, the API 525 is a "feedback" type compressor, such as the 1176 and 660, etc. An input (threshold) control and output (make-up gain) control are provided. An additional "Ceiling" fine tune function modifies threshold and make-up gain for precise changes in compression without changes in output.  A compression/limit switch sets ratio at either 2:1 or 20:1. Attack time is as fast as 15u/s. Four auto release modes are offered via two switches, 0.1s, 0.5s, 1.5s, & 2.0s. A De-Ess function inserts an inverse vocal energy curve filter in the detector for effective sibilance/p-pop reduction. The 525 is an identical re-issue of one of the most popular API products ever. The API 525 is perhaps the most successful solid state feedback compressor in history. It delivers dynamics control behavior unlike VCA "feed forward" compressors so common today. A remarkable multi-function "ceiling" control can increase gain reduction (lower threshold) while simultaneously raising output level to match, so the user can alter dynamics "on the fly" without level changes. This re-issue design has been taken from the original blue prints and spec control drawings from the API archives.        FEATURESReissue of API's original 525 from the early 70'sPeak detecting "feedback" compressor/limiterVariable Threshold and Output levelsUnique "Ceiling" control combines key functionsVU meter for monitoring gain reduction4 Switchable release modesDe-Ess functionTraditional API fully discrete circuit designHardwire bypass

The Little Devil Compressor is a discrete, transformer-balanced 500 Series module that combines Wade Goeke’s designs with studio favourites of the past. It draws on Chandler Limited’s LTD-2 and Germanium Compressor, as well as the 2264 and 33609, to create an entirely new compressor.Discrete transformer sound and handmade construction are at its core. Controls such as wet/dry mix, sidechain filter and curve selection make it extremely flexible, and together with its intense tone they deliver a powerful tool in a small box.

The TG Opto is a handmade, fully discrete, mono, double-width 500 Series compressor. It is a relative of the TG1 Opto found in Chandler Limited’s TG Microphone Cassette, TG1 Limiter and Zener Limiter, and its lineage goes back to the EMI TG12413 limiters of the TG12345 mixing and mastering consoles of the late ’60s and early ’70s.Chandler Limited is the only company in the world authorised to develop, manufacture and market the “Official Equipment” of EMI and Abbey Road. With the TG Opto, the TG2-500 preamp and the TG12345 MKIV equalizer you can build a complete TG console channel in a 500 Series rack.