The Band Compressor was designed for fixing and enhancing by compressing and trimming a specific range of an instrumental or vocal track. It makes the track tonally more consistent and controls abberations in crucial frequency ranges.The Band Compressor is a sort of dynamic EQ that works only on a selected frequency band.The bands are:LOW - shelving response below about 120Hz. Perfects for bass, drum subgroup, vocals (it controls pops and proximity effect) and overall mix.L.MID - peaking 250-300Hz, the "hard", muddy low mids that usually are very demanding to be controlledLOWS&HIGHS - both lows and highs, the "contour" curve. To be used as an automatic "loudness" controlH.MID - about 3kHz peaking, the presence band. If excessive boost is applied it gives unwanted strident and harsh quality causing listening fatigue, compressing the band avoids the effectHI - shelving response from 5kHz up for brightness control. Good on everything, especially on vocals (it lets to combine HF boost with a de-esser in one process), guitars and drums overheads, as it allows to brighten the drums without cymbals all over the place.AIR - shelving response from 10kHz upward with a steeper slope. Designed for overall mix processing.Only the selected band is controlled (cut, boosted or compressed), the rest of the frequency spectrum is unchanged and remains intact.The direct path can be muted with the DRY CUT switch. It lets to listen the signal that is being processed and can be used for parallel processing as well.The band filters are passive apart from the L.MID filter and the filtered signal is compressed by a high quality FET compressor with ratio and attack/release times carefully selected for each band.If the compression knob is on 0 then no compression is taking place, the unit is working as a one band EQ with the range from -10dB to +12dB.In contrast to multiband compressors, the BC is very easy and intuitive to use and its minimal signal path topology yields less audio degradation.

The Amtec DST-5A is a clipper/distortion module designed to be used in API-500 compatible racks. It is a line level device capable of producing a broad spectrum of harmonics.Its versatility is greatly increased by a novel mixing stage, a choice of 4 different transfer curves and simple, but carefully fine-tuned EQ stages.It can be used at every stage of audio work on individual tracks, sub-mixes or full mixes. The DST-5A offers anything from subtle peak limiting (rounding off the transients and increasing loudness) and tone enhancing thatbrings out character of vocals, drums, guitars, synthesizers etc. to fully distorting the original tone.It can be used to simulate the saturation aspect of tape recording, to add crunch, grind and growl with a choice of warm or raspy distortion qualities.

The MIP-5A is a microphone preamp that is a 500 version of our old prototype micpre that worked like a charm.Transformer-balanced input and output, fully discrete class-A amplification. The topology is unique, no typical DOA.All controls are self-explanatory apart from maybe the OUTPUT PAD switch which reduces the output level by 6dB using the output transfomer (to help enjoy the MIP-5A's distortion) and the WOOL switch which changes the transfer function for certain parts of the frequency spectrum and makes the overload characteristics very smooth and gentle. The clipping distortion sounds quite dark. When the WOOL function is deactivated the overload is conventionally bright and buzzy.

The Amtec Model 099 is a tube compressor/limiter based on the legendary Fairchild 660. The unique character of the original unit is retained with an addition of some new functions and options.The signal path topology is the same as in its famous precursor from the 50's, but switchable output attenuator is also included. The compression/amplification takes place in a single push-pull tube stage, that consists of readily available tubes. The tubes form a feedbackless amplification circuit with variable-mu characteristics that interfaces with the outside world via high-quality custom input and output transformers.The output attenuator allows to reduce the output level and increase the input level, so that more harmonic content can produced by the 099.The output attenuator control also acts as a termination switch. The original Fairchild unit is unique in that the variable-mu tube gain stage drives the output transformer directly and any load on the output that is other than the proper 600 ohms load disturbs the operation of the gain stage by changing its transfer function. It leads to restricted gain reduction law and also changes the frequency response.We eliminated the problem by including the termination switch. If the following device has modern-style high-impedance "bridging" input, it can be terminated right at the output of the 099 (using the Hi-Z part of the switch), so that the overall load is 600 ohms.The sidechain circuit that controls the actual compression has transformer-balanced input and can be internally routed from the output of the unit post-compression (i.e. feedback topology that is typical to the Fairchild and majority of other compressors, this position is marked NORMAL), from the input of the unit pre-compression (feedforward topology, marked FRWD) or from the external input on the back of the unit (position EXT).This sidechain signal can be filtered, so that the compression is not triggered evenly by the whole frequency spectrum. The rotary switch FILTER lets the user to choose from no filtering, one of four low frequency cut positions or the high frequency boost position marked D-S (de-essing).The compression slope switch has six positions from gentle compression (2:1) to limiting (20:1). The compression slopes are of soft-knee characteristics.The standard six time constans of the original Fairchild are preserved with no changes to them and are marked 1 to 6 around the Time Constans knob. These constans have fast attack time, so to greatly increase the 099's versatility we added some new time constans. These constans are marked P, S, E and D and offer longer attack times, therefore are better suited to processing of drum and bass tracks, as well as the whole mixes. The position D (like Drums) has especially long and uniquely shaped attack.On the other hand, the position marked F is the faster version (both attack and release) of the standard preset 1.The unmarked position at the bottom of the switch disables any compression.One feature of the 099, particularly rarely seen in pro-audio equipment, is presence of the Stand-by switch. It allows to greatly reduce anode voltage supply, while keeping all of the other internal voltages intact (including the heater supply) and thus preserving the tube life, while not in use for prolonged period.Unlike the original unit, the gain reduction meter scale in the 099 is accurate.The entire calibration of the unit and the tube replacement can be done without the need to take the unit out from the rack. Each tube in the 099 has independent balance trim control making the calibration quick and easy.

The PEQ-10 is a 2U-high mono tube unit based on the Pultec EQP-1A. This is however not a faithful copy of the original, but rather an improved version which, besides increased abilities, preserves the sonic quality of incoming signal. Simple at first sight the equalization section is in fact very flexible giving you the tool to powerfully shape tonality without side effects. With the low frequency section you can boost bass without muddying the low mids, and the high frequency section can add sheen and "air" in an almost exciter-like fashion, but with much more natural results. Introduced warmth in the bottom end and sparkle in the treble give individual tracks and entire mixes more depth, punch, presence and clarity. The PEQ-10 consists of a passive equalizer that is coupled to a tube amplifier restoring the gain. The passive circuit uses inductors and capacitors to achieve equalization giving the most musical results and the least distortion possible. The gain recovery amplifier is unique in several respects. It uses commonly available tubes in a high-voltage, feedbackless push-pull circuit coupled to specially wound output transformer which provides balanced and floating output. Another improvement is increased input impedance. A lot of contemporary equipment cannot drive the traditional 600 ohms load sufficiently. The PEQ-10 has input impedance more than 3 times higher, thus it doesn't load down the output of the preceding device. Very gentle equalization curves make Pultec-type EQs sound very musical. This device is not an exception. The equalizer has a low frequency shelving boost and attenuation, which can be used simultaneously for special effects, as well as a peaking high frequency boost with variable bandwidth and a high frequency shelving attenuation. As for the make-up amplifier, it uses a configuration that has intrinsic high bandwidth and linearity, and does not need feedback to improve them. As a result you end up with minimum transient distortion. It also gives more open and effortless sound. The bypass switch omits equalization section leaving tube amplifier in the signal path. The power supply has full regulation of the +B and heater voltages. Each unit is hand-build with great attention to details. Despite having old-style features, the PEQ-10 is very versatile and is perfectly adequate to modern recording techniques. With new frequencies it became yet more flexible than the original. This is the ultimate equalizer to make silky smooth enhancements to vocals, bass, drums and complete mixes, but all of the other sources would benefit as well. SPECIFICATIONSLOW FREQUENCY SECTION:Shelving Boost/Attenuation @ 20, 30, 60, 100 HzHIGH FREQUENCY SECTION:Peaking Boost @ 1.5, 2, 3, 4, 5.6, 8, 10, 12, 16, 20 kHz, 10kHz shelf.Shelving Attenuation @ 5, 10, 20, 40 kHzAll Boost & Attenuation controls are now stepped at 1, 2, 3, 4, 6, 8, 10, 12, 14, & 16dBGain: 0dB +/-0.5dBInput Impedance: >1.8 KΩ, balancedOutput Impedance: 50Ω, balanced and floatingMaximum Output Level: >+20dBu (1% THD) [600Ω]Frequency Response: better than 2Hz..40kHz -3dB [600 ohms]Tubes: (1) ECC82/12AU7, (1) ECC83/12AX7Power Requirements: 115V or 230V (factory option), 12VA

The ATG-1 Floor Processor is the perfect complement to the electric guitar. The push of a button will instantly tune your guitar with perfect intonation. An easy to use interface allows you to access a variety of functions including: guitar models, virtual capo, pitch shift, etc. You even have the ability to create and store your own alternate tunings and doublings as part of a preset. String-Tune: Utilizing Digital Signal Processing (DSP) technology to correct the pitch of each guitar string, String-Tune makes your guitar come through an amplifier perfectly in tune. Solid-Tune®: Constantly monitors the pitch of each individual string and makes any corrections necessary to ensure a perfectly intonated fretboard, while still allowing bends and vibratos. Alternate Tunings & Doublings: The ATG-1 features alternate tunings, including DADGAD, Drop D, Open E, and Open G. Doublings include Twelve String, Parallel Octaves and Fifths. You also have the ability to create and store your own custom alternate tunings and doublings! Guitar Modeling: Select from different guitar models and pickup models so your guitar will sound like the classic and modern electric guitars, acoustic guitars and bass guitars. Virtual Capo: Transpose your guitar up or down a full octave in standard or any alternate tuning. Presets: The ATG-1 has the capacity to store 64 presets for instant recall. The easy to use ATG-1 Floor Processor also includes stereo outputs, tone controls, and accepts MIDI control inputs. Capture creativity when it strikes while saving time in the studio and onstage. Note: The ATG-1 Floor Processor is only available for shipment to United States addresses. For international shipments click here to find our authorized distributor.

The Edge Strip bundle includes the stunning Edge Modeling Microphone, the Discrete MP ultra-linear mic preamp and our native AFX modeling plug-ins. These three elements work hand-in-hand to deliver a locker full of unobtainable vintage mics and a rack full of classic outboard gear, all for a fraction of the price of the originals

The API 2500+ Stereo Bus Compressor allows adjustment of sonic qualities to alter the punch and tone of the stereo mix. The 19-inch, rack-mountable unit features a dual-channel design that can be configured for stereo compression or for use as two separate units via a single compression setting. Among the many qualities which make the 2500+'s unique is its use of API's patented THRUST® circuit for a chest-hitting, punchy bottom end. Another distinctive feature of the 2500+ is its selectable "old" or "new" compression, with the old style using the "feed back" type of compression found in the API 525, and the new style using the "feed forward" type in which the compressor side chain is fed directly from the unit input. Additionally, the output stage of the 2500+ offers an auto-makeup gain button that permits the user to vary the threshold or ratio while automatically maintaining a constant output level. Added to the 2500+ is the Mix/Blend circuit. First featured in the limited production 50th Anniversary Edition, Mix/Blend control provides either cross fader or parallel mixing of the compressed and uncompressed signal. Three different user settings are offered: OFF - compressed signal only X (Cross) - allows the MIX control to adjust between 100% uncompressed to 100% compressed - increasing one, while decreasing the other || (Parallel) - allows the MIX control to dial in compressed signal to blend into the uncompressed signal, (which remains the same). The 2500+ ensures fidelity with its fully balanced design and two front panel VU meters showing input, output and gain reduction levels. The 2500+ features API's industry exclusive five-year parts warranty and offers the user the reliability, sonic excellence and long life characteristic of all API products. Features API 2520 Op Amps Expanded variable threshold between -20dBu to +20dBu Selectable ratio, attack, and release times Patented THRUST® filter with 3 settings for frequency dependent side chain control Variable link between left and right channels Old "feed back" and new "feed forward" compression Soft, Medium, or Hard knee for easy to sharp compression Auto or manual gain make up 1/4" balanced side chain inputs Output clips at +32dBu New Mix/Blend circuit "Over Threshold" LED illuminates when input audio crosses the set threshold Stereo analog meters to show input level, output level, and gain reduction Full hard-wired relay bypass

Features API's Classic 312 Microphone Preamp in a 500 Series module Vintage Style Analog VU Meter Maximum 69dB of gain Traditional API fully discrete circuit design with 2520 Op Amp Proprietary AP2516 Input Transformer 20 dB pad switch 3:1 Output Transformer Tap Selection Switchable 48V phantom power Peak LED

Features Classic API Circuit Design Uses API 2520 Op Amps Variable Output Level Control 3:1 Output Transformer Tap Selection Four XLR Mic Inputs Four 1/4" Un-Balanced Inputs Front Panel Polarity Switch Front Panel 20 dB Pad Switch Front Panel Mic/Line Switch Front Panel 48V Power Switch

Features Classic API Circuit Design Uses API 2520 Op Amps Variable Output Level Control 3:1 Output Transformer Tap Selection Four female XLR mic inputs Four front panel 1/4" Hi Z instrument inputs Front panel polarity switches Front panel -20dB pad switches Front panel mic/instrument switches Front panel 48V power switches   Like the API 3124+, the 3124V is a high quality, compact, 4-channel mic preamp. It is equipped with the RE-115 K mic input transformer and the proprietary output transformer found in all API mic pres and throughout the API product line. Additionally, the 3124V offers Variable Output Level Control and switchable 3:1 output transformer selection. The unit has an internal 48-volt phantom power supply, which is switchable for each channel, as well as -20dB pad switches that affect both the mic and Hi-Z instrument inputs, both located on the front panel. The 3124V also features up to 65dB of gain. Additionally, the Hi-Z front panel inputs feed directly to the op amps, which allow a low level input such as a guitar or bass to be amplified without a matching transformer or direct box. These Hi-Z inputs can take levels as high as +20dBu, making them perfect for keyboards and other high level devices. The mic preamp outputs are on rear panel male XLR connectors.

The API 500-6B lunchbox is a 6-slot rack designed to accept all API standard 5.25" X 1.5" modules. This quality allows an engineer the flexibility to bring along specialized EQ effects to any situation: 550A, 550b or 560. The lunchbox is self-powered with a rear panel selected AC voltage switch and a removable power cord. The input/output jacks are XLR. The lunchbox comes standard with a +48 volt internal phantom power supply, bussed to pin 15 for interface with the API 512c Mic Preamplifier.API makes several modules for the 500-6B, including the 512c Mic Preamplifier, the 525 Compressor, the 527 Compressor, the 550A 3-band EQ, the 550b 4-band EQ and the 560 Graphic EQ. Combinations of these modules make perfect stereo recording packages (two 512cs and two 550bs) or vocalist's box (one 512c, two EQs and one 527).Other uses for the versatile lunchbox include:    Multi-track recording of acoustic and electronic audio sources    Sound reinforcement systems and recording to multi-track formats    Multiple facility projects where portability is a plus    Broadcast and audio for video production    Custom channel input strips Features:    Holds 6 API standard modules    215mA per slot    DB-25 connectors for easy input and output connection    XLRs to access channels 7 and 8 of the multipins    Power rail LED indication    Self-Powered, 100 to 250 Volts switchable, 47 to 63 Hz    Rubber feet & carrying handle for portability    Rugged steel chassis    Perfect for remote recording of Vocalist and InstrumentsSpecifications:Power Consumption, Quiescent:     .66 WattsSize:     15.5" X 5.5" X 7.5" DeepSize (Boxed for Shipping):     20.25" X 9.75" X 12"Actual Weight:     10.22 lbs.Shipping Weight:     12.65 lbs.

10 slot Rack with Power SupplyThe API Model 500VPR is powered externally by a tri-polar power supply and is designed to accept API standard format 5.25" X 1.5" modules. The 500VPR is internally wired for PIN 2 hot, and comes with the API L200PS. The input/output jacks are both XLRs. The 500VPR can hold up to ten API modules. API makes several modules to fit this rack, including the 550A, 550b, 560, 525, and 512c. Like all API products, the 500VPR rack enjoys API's standard 5 year warranty.Specifications:Size:     19" X 5.5" X 7.5" DeepSize (Boxed for Shipping):     22" X 10.5" X 16"Actual Weight:     7.62 lbs.Shipping Weight:     10.86 lbs.

API 505 DI Direct Input Like the console-based API 205L, the 505-DI is specifically designed to accept a guitar, bass or keyboard direct input while minimizing any loading effect on Hi-Z instrument pickups. Additionally, the 505-DI's Gain Control is used to normalize an instrument's input level, up to a +4 dBu output level. API's unique TONE control reduces potential low end "mud" in the signal, while turning on the BRIGHT switch adds additional clarity if desired. The various combinations of TONE and BRIGHT controls can eliminate the need for any EQ on the instrument while recording, keeping the signal path short and pure. This minimal signal path eliminates the need to use a standard direct box, which many times still requires a mic input, equalizer, and a fader to get the signal to a recordable level. The 505-DI is capable of boosting any instrument to a hefty line level without additional amplifiers. Use of the 100K / 400K LOAD switch allows the tone of the pickup to be altered slightly, alternately brightening or darkening the high frequency content. When inserting an instrument with an internal preamp or a line level instrument such as a sampler or a keyboard, the 505-DI offers a 20 dB PAD switch to drop the level without loading, thereby retaining the integrity of the incoming signal. Features Wide Range Gain Control with 55dB of gain Front Panel Hi-Z Input Front Panel Thru routing TONE Control helps customize your sound BRIGHT Switch boosts clarity and presence 10 segment LED VU meter for monitoring output level Peak Output LED Indicator 20 dB pad switch, applies to mic/line/instrument 100K / 400K Switchable Load Traditional API fully discrete circuit design Uses the famous API 2520 and 2510 Op-Amps

The API 512c is a mic / line / instrument preamp designed to provide a low noise, unusually good sounding front end for all types of audio systems. Sonically, it offers the distinct API sound at an extremely affordable price. Offering low noise (-129 EIN) and 65 dB of gain, the 512c includes phantom power, and switchable polarity, -20 dB pad and Mic/Line or Instrument selector. Front panel XLR and 1/4 inch connectors combined with rear panel mic access allows for additional flexibility when installed into an API lunchbox®, API's 10 position 500V vertical rack, or an API console.The API 512c remains faithful to the circuit designs of API's founder, Saul Walker. Fully featured and still hand assembled, the 512c carefully preserves the original sound character that made it so much a part of the early days of recording. Offering high headroom and a wide variety of inputs and input access points, it is equally at home in the commercial recording studio as it is in the home project studio.The 512c Mic/Line Preamp makes use of the 2510 and 2520 op-amps and therefore exhibits the reliability, long life, and uniformity which are characteristic of all API products. Features:Mic Preamp with 65 dB of gainFront and Back Panel Mic Input AccessLine/Instrument Preamp with 50 dB of gainFront and Back Panel Line/Instrument InputLED VU meter for monitoring output level20 dB pad switch, applies to mic/line/instrument48v Phantom switchable powerTraditional API fully discrete circuit designUses the famous API 2520 Op-AmpTechnical Specifications:Rear Connector:     Output on edge connector, MIC Input on edge connector, can be defeatedFront Connectors:     XLR MIC Input, HI-Z 1/4" Unbal InputGain Range:     MIC, 10 dB min, 65 dB max. Unbal HI-Z Input, 14 dB min, 50 dB maxMaximum Input Levels:     MIC, +8 dBu, Unbal HI-Z Input, +36 dBuInput Impedance:     MIC Input, 1500 Ohms (150 Ohm mic), HI-Z Unbal Input, 20 K OhmsOutput Impedance:     Less than 75 Ohms, Transformer BalancedClipping Level:     +30 dBuFrequency Response:     +0, -.3, 30 to 20 kHzNoise:     Equivalent Input Noise: -129, Mic In. -125, Un-Balanced In.Actual Metered Noise: Mic, -95 dBu, Un-Bal., -90 dBuDistortion:     Less than .05% @ +4 Out, Less than .1% @ +28 OutSize:     1.50" X 5.25" X 6" DeepShipping Weight/Actual Weight:     2 lbs./1 lb. 7 oz.Power Consumption:     ±12/18 Volts/DC, @40 ma.

Features Mic Preamp with 65 dB of gain Variable Output Level Control 3:1 Output Transformer Tap Selection Front and Back Panel Mic Input Access Line/Instrument Preamp with 45 dB of gain Front Panel Combo-style XLR + 1/4 inch Line/Instrument Input LED VU meter for Gain Level indication 20 dB pad switch, applies to mic/line/instrument 48v Phantom switchable power Traditional API fully discrete circuit design with 2520 Op Amp Features API's unique Five Year Warranty The API 512v is a mic / line / instrument preamp, world famous for its ability to provide a low noise (-129 EIN) and unusually good sounding front end for all types of audio applications. Sonically, it delivers the instantly recognizable API sound at an affordable price, and in the scalable API 500 Series format. Offering an impressive 65 dB of gain, the 512v includes front panel Variable Output control, switchable 3:1 output transformer selection, phantom power, switchable polarity, -20 dB pad, and Mic or Instrument/Line selector. The front panel Combo-style XLR and 1/4 inch connector combined with rear panel mic access allows for additional flexibility when installed into an API lunchbox®, API's 10 position 500V vertical rack, or into an API console. The API 512v remains faithful to the circuit designs of API's founder Saul Walker. Artfully combining those circuits with API's proprietary transformers and the incomparable 2520 op-amp, the 512v is a highly musical and rich-sounding analog mic pre, equally at home in commercial recording spaces as it is in smaller home studios. Fully featured and still hand assembled, the 512v exhibits the reliability, long life, and uniformity which are characteristic of all API products.

Originally released in the 70's, the API 525 is a "feedback" type compressor. An input (threshold) control and output (make-up gain) control are provided, along with an additional "Ceiling" fine-tune function which 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. 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/pop reduction. The 525 design has been taken from the original blue prints and spec control drawings from the API archives.Release times vary with frequency, with high frequency / full bandwidth content released faster than lower frequencies for natural envelope tracking. Attack time is fixed, chosen to catch the fastest peaks, without "pumping". Equally useful as a tracking, mixdown or program compressor/limiter, the 525 utilizes "vintage" dynamics control and an easy to use multi-function control set. The 525 has a hard-wire bypass switch, a balanced input, and a pinout that is the same as all the other 500 series modules. Two or more 525s can be linked for multi-channel compression.The API 525 Compressor makes use of the 2510 and 2520 op-amps and exhibits the reliability, long life, and uniformity which are characteristic of all API products. Features:Exact reissue of API's original 525 from the early 70'sPeak detecting "feedback" compressor/limiterVariable Threshold and Output levelsUnique "Ceiling" control combines key functionsAnalog VU meter for monitoring gain reduction4 Switchable release modesDe-Ess functionTraditional API fully discrete circuit designActive Balanced Input/OutputHardwire bypass Technical Specifications:Input Impedance:     > 30 K Ohms, BalancedOutput Impedance:     100 Ohms, Transformer coupled, BalancedOperating Levels:     -15 dBu to +20 dBuMaximum Gain Reduction:     25 dBNoise:     98 dB below +10 dBu output, at 10 dB of CompressionHarmonic Distortion:     0.5% Max, 30 to 20 kHzAttack Time:     15 micro secondsRelease Times:     .1, .5, 2.0, 2.5 secondsDe-essing:     Inversion of the Voice Energy CurveSlopes:     Compression, 2:1, Limit, 20:1Metering:     Compression or Limiting-Illuminated Analog dB meter, shows Gain ReductionFrequency Response:     ±.5 dB, 30 to 20 kHzPower Requirements:     ±12/18 Volts/DC, @80 ma.

Seit den frühen 1970er Jahren und der Neuauflage vor über 20 Jahren hat sich der 525 Discrete Compressor als einer der am meisten geschätzten Vintage-Style-Kompressoren in der Branche etabliert. Aufbauend auf der leistungsstarken Kernschaltung des ursprünglichen 525, behält der neue 525A den diskreten Audio-Signalweg bei und erweitert die Funktionalität für noch mehr Anwendungen im modernen Studio. Er kombiniert gekonnt APIs firmeneigene Transformatoren sowie die 2510- und 2520-Operationsverstärker und bewahrt die klanglichen Eigenschaften des Originals, während er die Zuverlässigkeit, lange Lebensdauer und Gleichmäßigkeit zeigt, die charakteristisch für alle API-Produkte sind.

Features Feed-forward or feed-back compression Hard or soft knee compression Patented THRUST® switch for frequency-dependent sidechain control Continuously variable, 31 position detented THRESHOLD control Continuously variable, 31 position detented RATIO control Continuously variable, 31 position detented ATTACK and RELEASE controls Continuously variable, 31 position detented OUT (output) level control 10-segment gain reduction/VU meter (GR/Output) Overload LED IN switch with soft and hard relay bypass Audio circuit uses the 2510 and 2520 discrete op-amps   The API 527A Compressor/Limiter takes its place alongside the family of API VCA based compressors, including the 225L compressor and 529, 2500, and 2500+ stereo bus compressors. Anyone familiar with these units will immediately be at home with the 527A. Features common to the line include "feed forward" (NEW) and "feed-back" (OLD) gain reduction methods selectable on the front panel, provide a choice of "that old way" or "the new way" of compression, for the highest level of flexibility in signal gain control. The "old way" or feed-back method is what most of the classic compressors used for the gain control circuit. The "new way" gain reduction is more typical of the newer VCA type compressors that rely on RMS detectors for the gain control voltage. There is a "SOFT"/"HARD" knee switch for an "over-easy" type compression resulting in a very natural, uncompressed sound or a typical sharp knee type that lends itself to a much more severe limiting effect. The patented THRUST® function can be switched in and out via the front panel as well, applying a filter before the RMS detector circuit that preserves that punchy bottom end. Two or more 527A Compressor/Limiters can be linked together via a DC link allowing multiple units to be combined for stereo and multichannel applications. The output level remains fairly constant regardless of the threshold or ratio control, much like the "more/less" Ceiling control on the API 525 Compressor. This allows for live adjustments without any noticeable gain changes in the program level. The 527A Compressor/Limiter makes use of the 2510 and 2520 discrete op-amps and exhibits the reliability, long life, and signature sound which are characteristic of API products.

Features Continuously variable detented Gain, Threshold, Attack, Ratio and Release controls 10 segment LED meters show Gain Reduction and selectable Input or Output Level Over Threshold LED Patented THRUST® Switch for frequency dependent side chain control 3 selectable compressor curve Knee settings Selectable New or Old switch for feed-forward or feed-back operation Selectable variable or auto compressor make-up gain Three way In/Out including full hard relay bypass Audio circuit uses 2520 and 2510 Discrete Op Amps with transformer output The new 529 Stereo Compressor combines the unmistakable sound of API's compression technology with the convenience and popularity of the API 500 Series format. Carefully designed to deliver a wide range of compression options, the 529 delivers warmth, clarity and punch, whether used for subtle adjustments or heavy compression effects. Based on the unprecedented success of the 2500, the 529 takes many of the features and controls from API's famous stereo compressor and puts them into the first dual slot 500 series module from API. This stereo compressor features API's patented THRUST® circuitry for a punchy low end, along with an Old/New switch that lets you choose between classic and modern compression characteristics: Old for vintage-style feedback compression and New for today's more common feed-forward compression. The Auto-makeup Gain button lets you adjust ratio and threshold controls without affecting the output level. Using API's discrete op-amps and transformer technology, the 529 delivers the legendary analog sound of API. The 529 is backed by API's unique 5 year warranty.

535-LA Line AmplifierFeatures: Continuously variable detented input level trim Polarity button 20dB Input Pad Calibrated Level mode Output Ratio selector Clip LED indicator Continuously variable Output Gain Traditional API fully discrete circuit design Audio circuit uses the famous 2510 and 2520 Op-Amps Traditional API fully discrete circuit design Modeled after API's highly prized console-based 325 booster cards, the 535 can both amplify and attenuate incoming and outgoing signals for ultimate flexibility—all while providing API's trademark warmth and tone.The 535 excels at adding warmth to a variety of signals. Recommended uses include: Warm up digital signals of all kinds Add Tone to Keyboard rigs Add warmth to any mix Audio playback devices, mic preamps, or audio processing devices that do not have their own level control will also benefit from the added tone and control of the 535-LA.The 535-LA also includes a balanced input, a polarity switch, a 20dB pad for incoming signal attenuation and a three position toggle switch, which allows for different output gain levels from the transformer. This is designed to drive long balanced lines with low distortion just as the 325 booster card does. Output gain range is from 6dB to 45dB. The 535 utilizes the discrete 2510 and 2520 Op-Amps along with API's proprietary transformers to create the unique, warm and reliable sound that API users expect. Like all API products, the 535-LA features API's unique 5 year warranty.

The beginnings of the 5500 circuit can be traced back to the original 550 equalizer designed by Saul Walker, the founder of Automated Processes Inc. The 550 was designed as a console equalizer, which uses an unbalanced input due to the architecture of the recording console. Because the ergonomics of a console dictate that the controls take up little space, sometimes the number of included functions can be limited. The 5500 is specifically designed to address these limitations; it has a balanced input, a true straight-wire bypass, an integrated power supply with noiseless muting and a range control that expands its versatility to mastering applications.The 5500's input XLR is connected to an active balanced circuit. The unit's output XLR is driven from a transformer coupled output and can drive any load from 600 ohms or more to full output capability. There is no change from input to output in the unit's polarity, so it is suitable in studios using either pin 2 or pin 3 as the "hot" connection. Additionally, the 5500 has a 1/4 inch input connector that interrupts any present signal on the input XLR. It is balanced and can be driven from either balanced or unbalanced sources. A positive signal on the tip will deliver a positive signal on pin 2 of the output XLR. Using the 1/4 inch input does not bypass any internal circuitry and does not change the gain or operating levels.Features:    Classic 550b Equalizer design    Two range switches to individually alter gain steps    Useable as a 550b, 550D or 550M    Peak/shelf switch on Hi and Lo bands    True hardwire bypass    Balanced In and Out on XLR    Unbalanced input on 1/4"    EQ In/Out switchTechnical Specifications:    Power Consumption, Quiescent:     .66 Watts    Size:     19" X 1.75" (1U) X 11.25" Deep    Size (Boxed for Shipping):     23.25" X 6.5" X 16"    Actual Weight:     9.68 lbs.    Shipping Weight:     13.51 lbs.

API 550aDiscrete 3 Band EQFew equalizers enjoy the respect and admiration of the coveted API 550A. Designed by the now-legendary Saul Walker in the late '60s, the discrete 550A was first used as a modular OEM equalizer. As the industry rapidly embraced the sonic quality of the 550A, it quickly found its way into many custom console designs by Frank DeMedio and other leading engineers. Many of these consoles are still in use today.The 550A provides reciprocal equalization at 21 points in 7 steps of boost to a maximum of 12dB of gain at each point. The fifteen equalization points are divided into three overlapping ranges. The high and low frequency ranges are individually selectable as either peaking or shelving, and a band-pass filter may be inserted independently of all other selected equalization settings. Frequency ranges and boost/cut are selected by three dual-concentric switches, and a pushbutton "in" switch allows the EQ to be silently introduced to the signal path. A small toggle switch is used to insert the band-pass filter into the 550A.The combination of Walker's incomparable 2520 op amp and his "Proportional Q" circuitry gives the 550A user an uncomplicated way to generate acoustically superior equalization. Features:    3 bands of classic API equalization    Each band offers 7 API selected frequency centers    Reciprocal and repeatable filtering    Maximum 12 dB of boost/cut per band    EQ Band 1 and 3 offer shelf/peak switching    "Proportional Q" narrows filter Q at extremes    Traditional API fully discrete circuit design    High headroom +30 dB clip levelTechnical Specifications:    Input Impedance:     66 kΩ high level, 17 kΩ low level   Output Impedance:     Less than 85Ω (transformer isolated)   Nominal Operating Level:     –15 dBm to +12 dBm   Insertion Loss:     None (bridging)   Frequency Response, Unequalized:     ±0.5 dB 30 Hz to 20 kHz   Noise:     Unequalized, output noise of –90 dBm, high level strapping and, –98 dBm, low level strapping, 20 Hz to 20 kHz unweighted   Distortion:     .05% THD max, 30 Hz to 20 kHz @ +4 dBm, .07% THD max, 30 Hz to 20 kHz @ +18 dBm   Clipping Level (3% THD):     +30 dBm   Power Requirement:     ±15 volts to ±18 volts @ 70 ma                        Toggle Switch:50 Hz to 15 kHz band-pass filter In or out                        Push Button: LF range Peak or Shelf                         Push Button: HF range Peak or Shelf                        Push Button: Equalization In or Out                        Tally light when In   Connector:     30 pin PC connector supplied   Size:     1.5" X 5.25" X 7.75" Deep   Size (Boxed for Shipping):     4.5" X 6.25" X 10.25"   Actual Weight:     2 lbs.   Shipping Weight:     2.53 lbs.

Based on API's original 550 from the late '60s, the API 550b is a continuation of the EQ that played a major role in the history of music recording, but with an additional filter band and several new frequencies. Incorporating API's exclusive circuitry and proprietary components (such as the legendary API 2520 Op Amp), the 550b artfully blends the past with the present. So many hit records still depend on the unique 550 sound that engineers around the world find it to be an invaluable tool. In fact, the 550b design has been taken from the original blue prints and spec control drawings from the API archives. It is unlike any other EQ you will ever use.Rather than offer a huge assortment of complex features, the API 550b provides exactly the right number of controls. Its four EQ bands are overlapped significantly to aid in dual roles as problem solver and sweetening device with each band offering seven switchable filter frequencies that span four-to-five octaves. These frequencies, purposely selected to be musical rather than numeric, were selected by an experienced "who's who" list of the industry's most proficient engineers.Making use of API's "Proportional Q," an innovation designed by Saul Walker in the '60s, the 550b intuitively widens the filter bandwidth at minimal settings and narrows it at higher settings without the need for additional bandwidth controls. This unique feature minimizes the "phase-shift" sound found in many equalizers. In addition, the reciprocal nature of the 550b enables the user to "undo" what has been done previously with exact precision.The benefits of the API 550b are most obvious to those who work with EQ on a continuous basis. If major tonal restructuring is required, the extraordinary headroom made possible with API's 2520 Op Amp offers the predictable and warm analog performance, even under duress. With a surprisingly wide range of tonal variations, the 500b is an invaluable and professional audio tool with great flexibility and excellent sonic ability. Features:Four bands of our famous sounding equalizationEach band offers seven API selected frequency centersReciprocal and repeatable filtering12 dB of boost/cut per bandEQ band 1 and 4 offer shelf/peak switching"Proportional Q" narrows filter Q at extremesTraditional API fully discrete circuit designHigh headroom +30 dB clip levelRe-issue of 1967 API 550 EQ with an extra bandTechnical Specifications:Number of Bands:     FourFilter Type:     "Low" and "High" bands are Peak/Shelf switchable. Low-Mid and Mid-High are peaking typeFilter Frequency Centers:     Low: 30, 40, 50, 100, 200, 300, 400HzLow-Mid: 75, 150, 180, 240, 500, 700, 1KhzMid-High: 800, 1.5K, 3K, 5K, 8K, 10K, 12.5KHigh: 2.5K, 5K, 7K, 10K, 12.5K, 15K, 20KFilter Boost/Cut:     ±12 dBFilter Slope:     12 dB per OctaveInput Impedance:     18.5 K +4 in, 7.5 K -2 inOutput Impedance:     Less than 75 OhmsNominal Levels:     -15 to +15 dBuClipping Level:     +30 dBu @ ±16 VFrequency Response:     +0, -.3, 30 to 20 kHzNoise:     Actual, unw noise, <-98 dBu, 20-20 kHzDistortion:     .07% max, @ +18 dBu OutputConnectors:     15 position .156sp edge connectorSize:     1.5" X 5.25" X 6" DeepShipping Weight/Actual Weight:     3 lbs./2.5 lbsPower Consumption:     ±12/18 Volts/DC,@ 40 ma.