Gain Reduction | Pro Audio Hardware Compressors and Limiters

There's someone out there using this site from an Amiga.
 
http://en.wikipedia.org/wiki/Amiga
 
This deserves a lot of respect.
 
Didn't even know it had a browser!

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The Aphex Model 320A delivers intelligent compressor action, leveling and peak limiting simultaneously. This intelligent, versatile and highly affordable processor can be used to solve audio level problems and improve audio signals in the broadcast studio, recording studio, tape duplication house, film dubbing studio and in live sound applications. Patented control circuits include analog computers that continuously analyze the input signal and vary the control characteristics to provide for virtually undetectable operation, regardless of the dynamics of the program.
 
Extremely easy to use, you only need to set the Drive level to generate the desired amount of processing, set the Process Balance control between Leveling and Compression and adjust the Output level for unity gain. The Model 320A is then ready to provide complete dynamic control - smooth, inaudible compression, increased system gain, desired program density and the freedom from constant "gain riding" - fully automatically! Its unique circuit design actually enhances transient qualities, thus making even heavy processing undetectable.
 
The Model 320A provides the option of Dual Mono or Stereo operation. In the mono mode, you have two completely independent channels of processing to accommodate independent monaural signal feeds. In the Stereo mode, you can choose between linking only the leveling control signals or you can link both the compression and leveling signals. An intuitive front panel metering system displays input level, output level or gain reduction levels. All potentiometers are detented for accurate resetting of controls. A Leveling Speed (fast/slow) switch is located on the front panel, as is the defeat switch for the peak limiter. Operating reference levels are selectable from -10dBV, +4dBu or +8dBu. An RJ-11 connector is located on the rear panel to facilitate remote relay bypass of the unit.
 
-Intelligent Automated Gain Control (AGC) for consistent program levels
-"Invisible" compression characteristics assure tighter dynamics and virtually transparent performance
-Instantaneous peak limiting for effective system protection (user defeatable)
-Adaptive control circuits make for fast, simple set-up and no readjustment for varying program dynamics
 
The Model 320A is almost identical to its predecessor, with the primary improvement being the addition of a newly developed (patents pending) Frequency Discriminate Leveler (FDL) circuit. Lab tests and exhaustive research led to the discovery that, under conditions of program leveling, the human ear perceives the onset of low frequency (bass & percussion) transients differently from transients at higher frequencies. This perception, as it turns out, is a direct function of the relative attack time of the leveler. Without FDL, there is a significantly greater chance that low frequency transients can create an audible "bass pull back" effect. In addition to a potential loss of bass and/or low end "punch", mid and high frequency processing can be negatively impacted. To the listener, the effect can be heard as a perceived loss of bass or even "pumping" at the mid and treble frequency ranges.
 
FDL eliminates this problem by allowing low frequency transients to trigger a slower attack time on the initial transient. High frequency leveling is still controlled within the attack time determined by the onboard computer. From the listener's standpoint, the benefits are:
 
-No more bass pullback effect
-More bass punch for better music mixes
-Fast leveling can be used in more applications
-Reduced audio distortion in the leveling mode
 
Retail:
 
$250
 
Used:
 
$100-250
 
Verdict:
 
Well respected compressor that is transparent can be driven hard and delivers a great sound on a budget. Check out other Aphex products like the Dominator and Expressor too. Some have gained legendary status so this is a good investment if the condition is right.

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The same familiar striking front panel, machined from 1/4" aircraft aluminum, handcrafted solid aluminum knobs, LEDs mounted individually in machined stainless steel housings, custom VU meters with peak indicators, and heavy gauge chassis mark the 162SL as a leader for decades to come. The 162SL combines the best features of all the great dbx compressors, past and present, and gives you more versatile performance than ever before. In addition to having the auto attack and release as well as the hard knee threshold characteristics of the classic dbx 160, the 162SL offers AutoVelocity™ manual mode, in addition to classic dbx OverEasy® mode, made standard by the legendary dbx 165A. And speaking of the 165A, all of its features, including variable attack and release controls, as well as dbx’s latest limiting algorithm PeakStopPlus™, are included in the 162SL.
 
The heart of any dynamics processor is its VCA. The dbx 162SL is no different. It features dual proprietary dbx VCA modules. This state-of-the-art implementation of dbx’s original Blackmer decilinear VCA boasts an unheard of dynamic range and ultra-low distortion seen only previously in the Blue 160SLs. With sonic clarity designed for the studio, the 162SL maintains its superior performance in harsh environments, pure enough for the studio, rugged enough for the road was the engineering motto of the Purple Series of Compressors / Limiters. Like it's big brother, it takes full advantage of the best parts available and dbx's advanced manufacturing, including Jensen® transformers on each output standard. Following in the footsteps of the Blue Series 160SL, with the Purple Series 162SL, dbx continues to create to the most technologically advanced compressors in the world.
 
•Super fast manual attack and release
 
•High-Drive Jensen® output transformers
 
•Hard-knee/OverEasy® switchable
 
•Ultra-low distortion compression for unheard of clarity even under extreme gain reduction
 
•Program-dependent "Auto," Patent-pending AutoVelocity™ Manual, or fully variable attack and release modes
 
Retail:
 
$2100+
£1500
 
Used:
 
$2100+
£1500
 
Verdict:
 
Transparent workhorse compressor, extremely good.

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Every dynamics processor you'll ever need squeezed into 2U of space.
 
16 presets configured by prestigious industry professionals and Class A analog circuitry give you that sought-after professional sound at the touch of a button. Can be used as a front end, as a mix-down processor, or as a final mastering processor. It features a Focusrite Class A mic pre with both DI and mic inputs for clarity without coloration. Following this is a stereo preset compressor which is entirely editable. It also features a spatial enhancer; TubeTran technology for controllable tube warmth; and high-quality (16/24 bits and 128X over-sampling) A/D converter. A comprehensive visual meter ensures optimum levels at all times. Balanced/unbalanced TRS outputs.
 
Focusrite Platinum Penta Stereo Analog Preset Compressor Features:
 
  * Can be used as a front end, a mix-down processor, or a final mastering processor
  * Direct input for both mics and instruments
  * Focusrite Class A mic pre with both DI and mic inputs for clarity without coloration
  * Focusrite stereo preset compressor with 16 presets for perfect compression at the touch of a button, and which is entirely editable
  * TubeTran technology for controllable tube-style warmth
  * Analog spatial enhancer allows you to create an ambient, spacious mix
  * 16/24-bit/128X oversampled converter with a sampling rate of up to 96kHz
  * TRS balanced/unbalanced outputs
 
Retail:
 
Discontinued
 
Buy: $100-120
 
Verdict:
 
Focusrite do make better gear but this one that isn't universally liked.

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Most compressor/gates provide less than musical compression, coupled with gating that swallows transients—or closes early, cutting off decay and reverb tails. The superb engineering in the 266XL ensures that both its compression and gating provide versatility and excellent sonic performance in situations where other compressor/gates typically produce undesirable processing artifacts.
 
When using the 266XL’s AutoDynamic™ Attack and Release controls, artists and engineers will find that the center settings deliver classic dbx compression, while the full control range produces voicings that extend from slow “leveling” to aggressive “peak” limiting.
 
The Auto Dynamic™ circuitry continuously adjusts the actual attack and release times to optimally match the program material. Since users aren’t restricted to using the Attack and Release controls only in “peak” operation, they can tailor the response of the 266XL for individual tracks, mixed program material, special effects or system protection. As a result, production studios can use the versatile 266XL to replace multiple “single-purpose” limiters while sound reinforcement users can standardize on the 266XL for all of their applications.
 
The 266XL’s advanced gate circuitry uses a completely new, program-dependent timing algorithm to produce ultra-smooth release characteristics—even with complex signals, such as voice or reverb decays. dbx engineers went on to take advantage of the wide dynamic range and high precision of the dbx® VCA to design in an extra-wide threshold range and ensure top gating performance for each application.
 
Separate precision LED displays for gain reduction, compression threshold and gate threshold allow quick, accurate setup, while the 266XL’s intuitive operation lets users easily smooth uneven levels, add sustain to guitars, squash drums or tighten up mixes. In Stereo couple mode, the Channel 1 controls become Master controls, and Channel 2 follows precisely to ensure a rock solid stereo image—even with high amounts of compression. Professionals and newcomers will find that the 266XL sets up rapidly and musically the first time it is used, and every time thereafter.
 
The dbx® 266XL processor is the result of an intensive engineering and product development effort aimed at taking advantage of the latest and best advances in manufacturing technology to deliver true dbx audio performance and reliability to our customers at the lowest possible cost. The 266XL puts a completely new level of compressor/gate performance within everyone’s reach.
 
  * Goof proof operation to smooth uneven levels, add sustain to guitars, fatten drums or tighten up mixes
  * New gate timing algorithms ensure the smoothest release characteristics
  * Program-adaptive expander/gates
  * Great sounding dynamics control for any type of program material
  * Separate precision LED displays for gain reduction, compression threshold and gate threshold allow quick, accurate setup
  * Stereo or dual-mode operation
  * Balanced inputs and outputs on 1/4" TRS and XLR
  * Side Chain insert
  * Classic dbx® "Auto" mode
 
Retail
 
$99-110
 
Used:
 
$50-70
 
Verdict:
 
Not universally loved. But if you want to learn a bit about hardware compression for cheap it might be a good one to test out.

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C300 is an easy to use dual engine dynamics processor that gives you superior compression/limiting and gate/expansion feasibilities. It features flexible control of the signal path, 16 gate/expander and 16 compressor/limiter audio-optimized presets with intelligent TC multi-band and full-band technology, innovative new style compression, state-of-the-art TC quality, and an extremely intuitive and straightforward user interface that gives you access to complex and comprehensive dynamic processing with a few buttons and simple operations only.
 
C300 is mainly meant to be used in insert applications.
 
The C300 gives you source-based presets that are tailor-made for various types of sources. Depending on the preset you select you have access to intelligent TC full-band- or multi-band technology.
The C300 multi-band processing is built on a state-of-the-art TC algorithm that bases it calculations on the incoming source, and that why it called source-based. A multi-band compressor, as opposed to a full band compressor, acts differently on different frequency bands. That means that each frequency band actually has its own little compressor working on it, with unique settings like threshold, ratio, attack and release. If you for instance prefer a steep compression on the lower frequencies, a soft compression on the mid frequencies, and a bright and light compression on the higher frequencies, you should use a multi-band compressor.
 
The C300 comes with several presets that are fully optimized for this kind of compression and youl be surprised to discover just how easy multi-band compression can be.
 
Based on thoughts behind parallel compression you get a completely new approach to working with compression. Now you can take a compressed signal and mix it with a dry signal and enhance all details in the music, just by turning the mix knob. What that does to the sound is that instead of pressing down the signal peaks you preserve all the higher dynamics when you play loud, and at the same time you bring out all the details from the lower end of the signal. Try and apply parallel compression on a drum kit. Youl discover that all the lower details are smack in the face, while all the bells and high dynamics of the snare and cymbals are preserved and ncompressed so to speak. And the really cool thing about it is that the C300 makes parallel or new style compression the easiest thing in the world just select the appropriate preset, and youe up and running!
 
The entire user interface has been laid out to be simple, intuitive and straightforward. All non-essential knobs and tweaking possibilities have been cut away, and replaced with innovative combinations and expansions of parameter indicators and knobs. For instance, the gate and the compressor are both controlled with the same knob, giving you improved and much faster access to important parameters.
 
The C300 gives you highly advanced TC algorithms that will process your sound with extreme precision, ultimate audio quality and outstanding performance. State-of-the-art audio converters are built in, ensuring your passage from analog to digital and back, is in the very best quality.
 
The C300 comes with a flexible routing feature that gives you all combinations of parallel and serial link modes. Stereo serial mode allows you to process a composite full-mix signal on both engines simultaneously, virtually giving you an extra device. With the C300 you can insert a stereo full-mix signal into one engine, e.g. compress it, and then send the stereo signal into the second engine, and e.g. limit it, and then send out a processed full-mix stereo signal. What that gives you is the full use of stereo processing on two serial connected engines, something that not normally attainable in this type of dynamics processor.
 
In normal dual/mono mode youl either use one engine as a compressor and the other as a gate or both engines as compressors or gates, having two individually processed mono signals coming out from each engine. Or, youl link the two engines together, and e.g. use the first engine to compress the signal, and then the second engine as a limiter, sending out a processed mono signal.
 
Features:
 
* Dual engine compressor/limiter gate/expander
 
* 16 compressor/limiter presets and 16 gate/expander presets optimized for selectable audio sources
 
* Mix features for new style compression
 
* Intelligent TC multi-band and full-band technology
 
* Detail enhancement via new style compression
 
* Flexible routing gives you all standard combinations of link modes + a stereo serial mode that virtually gives you an extra device
 
* No nonsense user interface
 
* Comprehensive metering
 
* Optimized key filters in gate mode
 
* High quality knobs
 
Retail:
 
£120-170
 
(Getting old now)
 
Used: £90-120
 
Verdict:
 
A good first cheap compressor that was well received when it first came out. But now there are better alternatives such as the Art Pro VLA and the RNC at this price. Neither notable nor anonymous.

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The ProVLA II is a tube driven Vactrol®-based Compressor / Leveling amplifier designed to excel in any professional audio environment. Superior performance and an incredible tone makes the ProVLA II and indispensable tool for tracking, mixing, mastering, dynamic control of live sound sources or for use in broadcast audio.
 
Capable of delivering a far more musical natural sounding and sonically transparent compression than competitive units in its class, the ProVLA II uses an Opto-electronic circuit rather than the more typical design VCA driven level detection circuit. This VCA-less design coupled with a 12AT7 vacuum tube in the gain stage makes the Pro-VLA II the ideal dynamic control device for critical audio applications.
 
Exceptional signal integrity with extremely low noise and low distortion is achieved in the ProVLA II by utilizing a transformerless design throughout.
 
Vactrol® Technology
Unlike typical compression units that use Voltage Controlled Amplifiers (VCA’s) to handle level detection, the Pro VLA II’s Opto-electronic design allows a far more transparent and musical sounding compression without sounding aggressive or un-natural. This Vactrol based optical electronic circuitry is the basic component of the classic highly sought after compressors of past.
 
Vactrol® design allows the ProVLA II to react to audio signal in much the same way the eye naturally adjusts to fluctuations in light levels – smoothly, quietly and almost imperceptibly.
 
Soft Knee Leveling
The ProVLA II is a soft knee leveling amplifier by design. Although capable of providing dramatic compression effects, the ProVLA II was designed to excel in any application where transparent, expressively musical dynamics control is desired.
 
Comprehensive Metering
Large highly visible backlit analog VU meters accurately display input and output levels while extremely fast 10-segment LED’s display gain reduction. For added functionality, the LED’s display either average level for mastering & mixing applications or peak hold for monitoring individual sources when tracking audio.
 
Versatile I/O
XLR and 1/4-inch TRS balanced inputs and outputs are provided to ensure the ProVLA II can connect with any audio source or hardware. A +4dBu/-10dBu mode switch optimizes ProVLA II I/O for either consumer or professional equipment.
Features
 
  * VCA-Less Vactrol Opto-Compression Design
  * Mastering Quality Audio Signal Path with Tube Gain Stage
  * Enhanced Link Mode – While in stereo link mode, channel 1 level control acts as a master output level and channel 2 becomes a balance control between them, - optimizing the Pro-VLA II for use as a mastering tool
  * Variable Threshold, Ratio & Output Controls
  * LED Backlit VU Input/Output Level Metering
  * LED Metering Indicates Both Average Level And Peak Hold
  * Accurate Ten Segment LED Gain Reduction Metering
  * +4dBu/-10dBu Mode Switch Optimizes Pro-VLA II For Interface with Professional OR
  * Consumer Grade Components
  * Active Balanced XLR And ¼-Inch Inputs & Outputs
  * Toroidal Transformer Reduces Mechanical & Electrical Hum
 
Specifications
Attack Time 0.25msec. to 50msec. variable
Dimensions 3.5in x 19in x 9.2in / 8.9cm x 48.3cm x 23.3cm
Dynamic Range greater than 100dB (20-20KHz)
Equivalent Input Noise @+4dBu: -99dBu (''A'' weighted) / @-10 dBV: -107dBu (''A'' weighted)
Frequency Response 10Hz to 100KHz (+/- 0.5dB)
Input Impedance 10K Ohms
Maximum Attenuation 30dB
Maximum Input Level +20dBu (in +4dBu mode) / +10dBV (in –10dBV mode)
Maximum Output Level +20dB max
Release Time Variable 150ms to 3s
Slope Variable 2:1 to 20:1
Total Harmonic Distortion less than 0.1% (typical)
Weight 10.5lbs / 4.76kgs
 
ART Tube Compressors deliver analog leveling/compression designed to work seamlessly with any recording, sound-reinforcement, and electronic instrument application. Our Tube Compressors excel at making tracks sound rich and full for both live audio engineering and studio recording applications.
 
ART’s tube compression circuitry is a hybrid design utilizing the latest and most advanced analog and tube technology, and has exceptional signal integrity with extremely low noise.
 
ART tube compressors utilize optical electronics (a device known as a Vactrol®), coupled with a 12AT7 vacuum tube gain stage for superior musical performance. Unlike typical compressors which use VCAs to control level detection, ART tube compressors are very musical, expressive and natural sounding.
 
Retail:
 
£200-£300
 
Used:
 
Verdict:
 
A very characteristic compressor, perfect on a budget. Some people use it on the mix bus, but otherwise ideal for compressing drums and bass with character. The only problem with this unit is the lack of side-chain. A good project for diy-ers. Good built and professional look and feel.

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Since its introduction in the mid 1970's, the dbx 160 series has been the world's most popular line of audio compressors. After the classic 160 (which is still used daily in many world class studios), came the 165, the 160X and the 160XT. The 160X/XT were the models that truly became the industry standard. Solid construction, fool proof operation, great sound, at-a-glance metering and a bulletproof output stage all contributed to its popularity with musicians, recording studios, consultants and installers, and broadcast media production people alike.
 
The dbx® 160A is a legendary dbx® 160 family of compressor/limiters. The same classic sound, easy set-up and no compromise metering is now married to an improved signal path and stronger chassis design. The result is industry standard compressor/limiter which is digital-ready and road tough.
 
Featuring switch-selectable OverEasy® and Hard Knee compression curves along with extremely wide-ranging threshold, ratio and output controls, the dbx 160A is up to any task. True RMS level detection provides the most natural-sounding dynamics processing available, from subtle compression to "brick wall" peak limiting. Choose low ratios and OverEasy® compression to transparently smooth out fluctuating vocal and instrumental levels. Or use the 160A's Hard Knee compression and high ratios (up to and beyond :1 and over 60dB gain reduction) for bombproof protection against overload distortion in digital recording, P.A. systems and broadcast signals. The 160A is fully compatible with +4/-10dB and balanced/ unbalanced systems, and its electronically balanced output stage is an outstanding line driver for long cable runs (an output transformer is optional). The 19-segment, switchable input/ output LED metering can be easily calibrated to any operating level. 12-segment gain reduction LEDs provide precise analysis at a glance.
 
The dbx® 160A's unique "INFINITY +" inverse-compression mode actually decreases the audio output level below unity gain when the input exceeds threshold, a real lifesaver for correcting overbearing vocal choruses and controlling runaway house mix levels. A detector input can be used with an equalizer for de-essing sibilant vocals and selectively smoothing out boomy notes on acoustic guitar and bass. And two 160As can be stereo-coupled to process an entire mix or instruments mic'd in stereo, without shifting the left/right image. Its musical sound, easy operation and unequaled versatility made the original dbx® 160 a world standard. The 160A follows that tradition, while meeting the challenges of a digital world.ent in the mix, or overall characteristics of 4 independent signals or control the gain leveling on a couple of stereo pairs, the dbx 160A is for you.
 
Retail:
 
£300-400
 
Used
 
£200-£300
 
Verdict:
 
General all purpose kick and drum compressor. Valued for its "over easy" compression. Extra Notes:
 
  * OverEasy® or classic hard knee compression with dbx's® ultra-musical program dependent attack and release times
  * Compression ratio variable from 1:1 through infinity :1 to negative compression
  * Precision dual RMS LED display monitors input or putput and gain reduction over a wide range and calibrates for different operating levels
  * Over 60dB of gain reduction available
  * Exclusive Infinity+ compression allows negative compression
  * Independent balanced and unbalanced outputs can drive 600 loads to +24dBm simultaneously. New floating balanced output stage drives any load
  * Optional output transformer capable
  * Strappable with another 160A for true RMS stereo summing operation

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The SSL XLogic G Series Compressor unit is a 1U rack mounting stereo compressor.
 
the SSL XLogic G Series Compressor utilises the classic SSL G Series centre compressor design elements within a SuperAnalogue design topology. This brings the dual benefits of spectacular audio performance with a universally acclaimed compressor characteristic.
 
The XLogic G Series Compressor uses the same classic twin VCA design as its console counterpart. Combined with improved input and output circuitry, this new unit provides improved audio performance, while retaining the dynamics characteristics that have provided numerous hit mixes for the world's best audio engineers.
 
SSL XLogic G Series Compressor main features include:
 
  * Legendary SSL G series stereo buss compressor
  * Gain reduction meter as fitted to the classic SSL console range
  * External side chain source select
  * Auto fade with rate control automatic linear fade in/out control
  * Remote connector for remote operation of the auto fade function
 
Retail
 
$2100+
 
Used
 
$2100+
 
 
Verdict:
 
Highly sought after mix bus compressor. Used to get the SSL console sound. You can try to built one at a fraction of the cost http://www.gyraf.dk/gy_pd/gyraf_diy.html to get close to the sound. Emulations aren't close.

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