Over the years, the use of compressors has become necessary for mixing and mastering. The plugin’s market has become saturated with all types and kinds of compressors.
From tube to VCA compressors, producers use them all for different sound signatures, feel, and overall vibe. Some compressor plugins are modeled after classic hardware units to provide an analog, vintage, warmer feel. Others implement digital technology to achieve a snappy, clean sound for use on drums, vocals, etc. However, one type of compressor that seems to be gaining some traction is the Opto Compressor and we will discuss it in this article.
To understand Opto Compressors, we need to know how compression works and the necessary controls ordinarily available to the user. Compressors function in a similar way to limiters, as in both plugins work to reduce the dynamic range of the audio, which is the difference in volume between the quietest and the loudest sounds in a track. Applying compression makes your track sound more leveled and cleaner since compression aims to maintain a good level of loud and quiet parts.
Basic compressor controls include:
A threshold is a limit beyond which the compressor is enabled. For example, if the threshold is set at -8dB, all signals which exceed that will enable the compressor to force those signals to duck down in gain to fit the limit (i.e compress them). Else, the compressor will be in a no compression state/disabled.
The “knee” corresponds to the way the compressor converts from a no compression state to a compression state. There are two types of knees; hard knee and soft knee. Hard knee means that when signals exceed the threshold, the compressor is enabled immediately and it feels “snappy”. On the other hand, soft knee means that when signals exceed the threshold, the compressor is enabled gradually and so it feels softer.
Attack control refers to the time it takes for the compressor to fully compress the signals. The fast attack is normally ranging from 20 – 800 microseconds, whereas slow attack is anywhere between 10 to 100 milliseconds.
The release is the exact opposite of the attack. It refers to the time it takes for the compression to be fully lifted off of the signal. It normally comes in the range of 40 ms to 5 seconds.
The compression ratio refers to how much a compressed signal is attenuated. The image below gives a clear representation of that.
Output gain allows the user to control the gain of the track after compression. This is useful for users to compensate for the gain loss due to compression.
- 1 What Are The Different Types Of Compressors?
- 2 What Is An Opto Compressor?
- 3 How To Mix With Opto Compression?
- 4 10 Best Opto Compressor Plugins (VST, AU, AAX)
- 5 1. Brainworx bx_opto Review
- 6 2. Tube-Tech CL-1B Review
- 7 3. ACME Audio Opticom XLA-3 Review
- 8 4. Waves Renaissance Compressor Review
- 9 5. IK Multimedia Opto Compressor Review
- 10 6. Softube Summit Audio TLA-100A Review
- 11 7. London Acoustics – Brighton Opto Tube Comp Review
- 12 8. Audiority LDC2 Compander Review
- 13 9. brainworx Millennia TCL-2 by TWINCOM Review
- 14 10. IK Multimedia White 2A Leveling Amplifier Review
- 15 Bonus Plugins:
- 16 1. Waves CLA-3A Compressor Review
- 17 2. ADHD Leveling Tool (FREE) Review
- 18 Conclusion
What Are The Different Types Of Compressors?
Tube compressors are the first generation of compressors. Due to their working mechanism, they normally tend to have a slower response (i.e. attack and release) when compared to other compressor types. This gives the tube compressors the vintage, warmer feel that a lot of producers and engineers look for.
Popular plugins that model tube compressors include the Fabfilter Pro C2 and the UAD Fairchild collection which models the classic Fairchild.
First introduced in the 70s, VCA compressors were very popular due to the invention of the integrated circuits (ICs) which meant that gain reduction could be achieved more efficiently and cheaper. Some of the most popular compressor units like the classic SSL Bus compressor or the DBX 160 have demonstrated the qualities of VCA to producers and engineers.
VCA compressors are known to produce a fast and punchy compression to the audio signal.
“Field-Effect Transistors” or FET in short use transistor circuits to emulate the sound of tube compressors. FETs are simple to use and are optimum when you need to quickly apply compression for vocals, guitars, bass, etc.
The 1176 compressor shown in the image above is the first FET compressor to hit the market back in 1967. It has then been a popular choice for musicians like Led Zeplin, Michael Jackson, and many more.
The 4th type of compressor is the optical/Opto compressor and is the main focus of this article:
What Is An Opto Compressor?
Opto or optical compressors usually utilizes a light element and an optical cell to affect the dynamics of an audio signal. Whenever the amplitude of the audio signal increases, the light element increases the light emission, which causes the optical cell to attenuate the signal’s amplitude more.
The image above shows the classic Universal Audio Teletronix LA-2A Opto-Compressor. LA-2A is considered the industry standard Opto compressor. Today, many of the classic, vintage compressors are being modeled into virtual instruments by developers in an attempt to achieve a similar sound signature.
How To Mix With Opto Compression?
While mixing, Opto Compression is best for creating smooth compression at a very high ratio as opposed to VCA which is best for attacking short, sharp transients. Opto compression produces a pleasant sound since the signals won’t be squashed dramatically.
Many producers and engineers use a combination of different types of compressors to approach a signal in order to get the best sound out of the input signal.
10 Best Opto Compressor Plugins (VST, AU, AAX)
The list below reviews some of the most popular and powerful Opto compressor plugins that we think are important for you:
1. Brainworx bx_opto Review
Released back in July 2015, the bx_opto by Brainworks is an Opto compressor plugin that is designed after traditional optical compressors but with a twist in controls to make it highly versatile.
Obviously, most of the Opto compressor plugins including the ones discussed in this article are inspired in some way or another by the classic LA-2A compressor, the bx_opto is no exception. The bx_opto is not as simple as the LA-2A in its interface as it offers a few more control knobs as opposed to the simple 2 main control knobs interface offered by the LA-2A.
These knobs offer the user more control over the sound design of the compression which makes this plugin highly versatile. In addition to that, bx_opto has an improved sound design over the LA-2A. For example, it does not add saturation as dramatically as the LA-2A does, which makes it easier to use for a pleasant punch at slower speeds and exciting urgency for faster speeds.
- Analog sound, which sounds warmer and more pleasant to the ear
- Bx_opto provides the user with more control over the sound color compared to traditional compressors
- Speed knob allows users to create a unique transient response by controlling the coefficient of a Light Dependent Resistor
- Sidechain filters that are fully sweepable
- Wet/Dry mix knob which allows for parallel Opto compression
This plugin requires Windows 7 or higher for PC and macOS 10.9 or higher for Mac. It comes in VST/VST3/AU/AAX formats and supports 64-bit devices only.
Overall, the bx_opto by Brainworks is an amazing plugin that produces exceptional sounding compression that even surpasses traditional compressors in quality. Sign up for the 14-day trial of this plugin and assess the quality of this plugin yourself.
2. Tube-Tech CL-1B Review
Initially released exclusively in AAX format for Pro Tools user, the CL-1B has quickly garnered attention and this encouraged Tube-tech to release VST, AU, and RTAS formats of the plugin to support all DAWs.
The interface of the plugin version is a carbon copy of the interface of the hardware version, with the exception of the sidechain bussing switch which has been replaced by a selector which allows user to select between external and internal sidechain. In addition to the interface, the plugin version of the CL-1B does a phenomenal job of mimicking the sound signature of the hardware mono Opto compressor.
When it comes to performance, the CL-1B plugin is peerless for both subtle and audible compression due to its pleasing characteristics possessed by its attack and release. The flexibility of the attack and release controls allow the CL-1B to be very versatile in creating snappy compression for sounds like snares and over-compression for instruments like guitar, bass, etc.
- CL-1B is equipped with a distinctive gain-reduction element that does not introduce distortion to the sound
- Sidechain bus select knob enables the user to choose between an internal and external sidechain
- Variable attack and release times which makes this plugin optimum for a wide range of sounds
- The CL-1B has a VU meter for users to monitor the input, compression, and output
- Threshold range from -40dB to 0dB
- CL-1B has a good frequency response ranging from 5Hz – 25kHz
This plugin supports Windows 7 or higher for PC and macOS 10.12 or higher for Mac. It comes in VST/VST3/AU/AAX formats and supports both 32 and 64-bit devices.
Overall, the CL-1B by Tube-Tech is an exceptional emulation of the widely popular hardware by the same company and for a small fraction of that price. Don’t forget to check some good free plugins here.
3. ACME Audio Opticom XLA-3 Review
Developed in collaboration with Brainworx, the ACME Audio Opticom XLA 3 is an incredibly powerful and highly flexible optical compressor plugin.
The original XLA-3 featured an optical circuitry with 3 compression responses that work to treat sound in different methods, resulting in different sound signatures. In addition to that, users had the ability to add focused harmonic coloring to the input sound and even go further to turn it into a powerful sounding distortion. Furthermore, you had the compressor/limiter, which provided both subtle warmth to a signal or a cranked-up crazy-sounding signal.
The plugin version was mainly developed by Brainworx and managed to perfectly emulate and include all the XLA-3 features into a virtual instrument, with the addition of a parallel mix knob, an adjustable noise floor, and an output trim control.
- As mentioned, the XLA-3 plugin offers extra features to the original hardware that add to the versatility and controllability of the effect
- Amp mode which enables users to add color and distortion to the audio signal without compensating in dynamics
- Since this plugin is developed in conjunction with Brainworx, it has an “LA-2A” feel to it in terms of sound. On top of that, users get to control the harmonic distortion
- Output Gain for saturation and Output trim for attenuation of the output signal
This plugin requires Windows 7 or higher for PC and macOS 10.9 or higher for Mac. It comes in VST/VST3/AU/AAX formats and supports 32/64 bit systems.
The XLA-3 is an interesting take on optical compressors since it utilizes a unique optoelectric circuit that extracts the best features of 3 different compressors and provides them to the user in one unit. ACME Audio Opticom XLA-3 is definitely one of the more expensive plugins in the market. However, many users claim that this plugin is worth its price. Thankfully, you get a 14-day free trial period for you to review it personally.
4. Waves Renaissance Compressor Review
A plugin by Waves needs no introduction at this point. Waves have always been the leading developers when it comes to analog-sounding plugins based on traditional hardware and the Renaissance Compressor is no exception.
The Renaissance compressor has an incredibly unique, easy-to-use interface with digital precision input for each controlling parameter.
- This plugin offers users two compression modes; Opto and modern Electro modes
- Renaissance compressor has an internal brickwall limiter to guarantee a clip-free output
- Auto release control (ARC) for higher RMS levels
- Renaissance compressor is very CPU friendly
- High-quality audio is ensured due to its 24 bit/192kHz resolution support
This plugin requires Windows 10 or later for PC and macOS 10.13.6 or later for Mac. It comes in VST/AU/AAX formats and only supports 64-bit devices.
The Renaissance Compressor by Waves is an extremely important Opto-compressor plugin that is used by many producers and sound engineers due to its analog sound and its digital precision parameters. Furthermore, it is a go-to plugin for many users due to its attractive price point.
5. IK Multimedia Opto Compressor Review
IK Multimedia is another developer that needs no introduction in the plugin’s world. The T-Racks Opto-Compressor comes as a part of their T-Racks 3 mastering software and as an individual plugin as well.
For this plugin, IK Multimedia has managed to emulate an interesting sounding vintage and come up with a top-notch Opto compressor plugin that we think you will love. The T-Racks Opto compressor manages to pin down all of the main characteristics of an Opto compressor like low distortion, gentle, and transparent sonic nature. In addition to that, the T-Racks Opto compressor also allows for an effective gain reduction as well as the distinctive coloration of the sound all with only 5 control knobs – Input, Ratio, Attack, Release, and Compression.
- Spot on the emulation of vintage and analog optical compressor
- Works as a standalone application as it comes in the T-Racks 3 mastering software
- High quality oversampling for highest quality output
- Sampling rate support of up to 192kHz
- Full-latency compensation to remove any lag that the plugin may introduce to the mix
- Straightforward and easy to use interface for maximum efficiency
This plugin works on Windows 7 or higher for PC and OS X 10.9 or higher for Mac. It comes in VST/AU/RTAS/AAX formats and only supports 64 bit systems.
Overall, the T-Racks Opto-Compressor by IK Multimedia is a top recommendation for every user looking for the “perfect” Opto compressor plugin as it offers that in high quality. In addition to that, it comes at a very reasonable price which makes it a good choice for many users.
6. Softube Summit Audio TLA-100A Review
Developed by the renowned Swedish developer Softube in collaboration with Summit Audio to create a virtual instrument version of the classic TLA-100A Tube Leveling Amplifier with a few extra exciting controls for the user.
The original TLA-100A hardware unit was a go-to compressor for many engineers for use on vocals and acoustic instruments, and it was pretty much an industry standard dynamics controller as it was present in most professional studios. The TLA-100A is more accurately referred to as a ‘Leveling Amplifier’ rather than a ‘compressor’, as it automatically controls the level of vocals without the knowledge of the user to maintain a presence.
The TLA-100A’s popularity came from its exquisite leveling, smooth workflow, and unmatched ease of use – all of which have been successfully captured into the plugin version as well. Summit Audio has a slogan of ‘set and forget’ which is not just marketing crap: just set the peak reduction knob to the required amount and watch it take care of the rest.
Since the TLA is a valve leveling amplifier, it has a soft knee response which as discussed gradually applies switches from non-compression to compression state to allow for a smoother sound.
The plugin version of the TLA adds a few extra controls to the hardware version including a Low Cut Filter to allow users to set the bass response for either the internal or external sidechain input which is great for an audio signal that contains a lot of low-frequency signals. In addition to that, users can control the Saturation which eliminates the need to overdrive the input signal to achieve the classic hardware color and saturation.
- The TLA-100A has a well-organized interface which makes its usage very easy
- Built-in parallel compression effect and a Low cut filter which can be switched to a signal input
- Every control parameter is modeled in great detail to achieve the perfect sound
- Users get a saturation knob to control output distortion which is naturally present in the hardware version
- Attack and release parameters have slow response times which make them have an amazing analog feel
This plugin requires Windows 7 or higher for PC and OS X 10.12 or higher for Mac. It comes in VST/VST3/AU/AAX formats and supports only 64 bit systems.
The TLA-100A plugin by Softube and Audio Summit is the perfect plugin for producers and engineers that want a software version for the classic TLA hardware compressor unit that was an industry-standard Opto-compressor at the time.
7. London Acoustics – Brighton Opto Tube Comp Review
The custom-built Opto compressor plugin by London Acoustics is a no-brainer when it comes to placement on this list of plugins. Due to its modern tube compressor concept, the Brighton Opto Tube Comp is suitable for a great range of applications but especially for vocals, bass, leads, and drums due to its fast response times.
Despite being greatly inspired by the classic Vactrol VTL5 optical photocell detector, it also models a custom-built compressor prototype with a totally new concept as well as a custom circuit tube preamp.
Its character is widely versatile. It can be smooth like an RMS Opto in normal settings or very punchy and fast in extreme settings.
- Internal sidechain which enables the user to adjust the low response at the desired level
- Fast attack and release times (0.1-75 ms for attack and 0.03-3.5 s for release) which makes it perfect for vocals and drums
- This plugin has a good peak reduction which ranges from 0 to -64 dB
- Output gain has a range of 0 to +24 dB
- The Opto Tube compressor has a built-in Hi-pass filter sidechain with a range of 0 to 250 Hz
Brighton Opto Tube compressor is compatible with Windows 7 or higher for PC and Mac OS 10.9 or higher for Mac. It comes in VST/AU/AAX formats and supports both 32 and 64 bit systems.
The Brighton Opto Tube compressor by London Acoustics is the only plugin mentioned on this list that does not directly model a popular Opto-compressor unit, but instead, it adds its own unique design and sound character which is respectable. It also comes at a pretty decent price considering its capabilities.
8. Audiority LDC2 Compander Review
LDC2 by Audiority is an Opto compressor with a slick, throwback design that models another vintage optical compressor unit.
LDC2 has an analog-sounding compressor and an expander that features exchangeable optical circuits as well as a solid-state preamplifier. In addition to that, it has a smooth and warm sound signature which makes it amazing for recording, live performances, mixing, and mastering.
- LDC2 consists of 17 real-time optical circuit models which allow for more detailed dynamics and sound signatures
- Ratio for the optical compressor is fixed at 4:1
- 40dB maximum gain reduction for the optical compressor
- Ratio for the optical expander is fixed at 3:1
- 30dB maximum gain reduction for the optical expander
- The side chain and the high pass filters both have an independent gain control
- LDC2 has a preamplifier that is diode-based
LDC2 requires Windows 7 or higher for PC and OSX 10.8 or higher for Mac. It comes in VST/VST3/AU/AAX formats and only supports 64-bit devices.
LDC2 is one of the more affordable plugins discussed in this review, which is quite impressive considering its efficiency, sound signature, and versatility. Opting to purchase this plugin is not a bad choice.
9. brainworx Millennia TCL-2 by TWINCOM Review
The TCL-2 is another brilliant Opto-compressor plugin. Obviously, it emulates the traditional TWINCOM hardware which features “Twin topology” technology. This gives the user the ability to choose between a full tube or a full J-FET/solid-state signal path.
The original TCL-2 hardware featured a full tube and a full J-FET/solid-state signal path. This has been perfectly modeled into the plugin version. Furthermore, the plugin allows the user to separately process the Mid (M) and Side (S) information, as well as control the Wet/Dry mix for each channel individually.
- Twin topology technology to allow for two perfect signal paths
- Superb stereo optical compressor which sounds crisp sonically
- 2 signal paths; All triode 300 vacuum tube and All discrete J-FET solid-state signal paths
- Two topologies – both have no transformers and are of pure, high voltage, Class A circuitry
- Despite the several control knobs, the TCL-2 remains clean and straightforward in its interface
TCL-2 is compatible with Windows 7 or higher for PC and macOS 10.9 or higher for Mac. It comes in VST/VST3/AU/AAX formats and supports only 64 bit systems.
Overall, the TCL-2 is an incredibly powerful Opto compressor plugin with surgical precision control knobs for maximum efficiency. Despite its might, many users believe that the price point for this plugin is unjustifiable especially since there are options out there that offer good sounding optical compressors for a fraction of that price. On the bright side, it comes with a 14-day free trial so you can try it out and judge for yourself.
10. IK Multimedia White 2A Leveling Amplifier Review
Another member of the T-Racks suite by IK Multimedia, the White 2A leveling Amplifier offers a slightly different take on the classic Teletronix LA-2A discussed before.
The classic LA-2A uses a lamp that is controlled by the side chain to alter the conductivity of a photosensitive device, which then controls the gain for the signal. This is an Opto-attenuator system and it has some unusual linearities that allow for a smooth and musical sound signature that works perfectly with vocals, as well as to add subtle warmth to bass instruments.
For the interface, users are greeted with gain control to manipulate the output signal, whereas peak reduction is used to specify the level of gain reduction to be applied. A meter can be switched to show readings from +10dB to +4dB. Additionally, users can set the choice of stereo from L/R or M/S. Finally, users are able to switch between the limiter and compressor using the switch provided.
The plugin version (the White 2A leveling Amplifier) offers the same control knobs but with additional switches for the stereo control. Now users have this “=” sign which links the two channels either L/R or M/S together and process them simultaneously instead of processing them separately. Moreover, users get to switch between limiters and compressors using the switch provided.
- Dead ringer emulation of the Teletronix LA-2A Opto-compressor in terms of interface as well as sound quality
- Modeling is quite extensive and detailed up to the T4A optical chip to emulate the behavior precisely
- As the name states, this is a 2 channel leveling amplifier, and it’s perfect for smoothing vocals and adding more punch to the overall mix
- 2 channel mode either stereo linked or Mid/Side modes for the bus compression
The OS requirements for this plugin are Windows 7 or higher for PC and macOS 10.9 or higher for Mac. It comes in VST/RTAS/AU/AAX formats and supports both 32 and 64 bit systems.
The White 2A leveling amplifier by IK Multimedia offers comprehensive emulation of the Teletronix 2A-LA. So if you are looking for that sound, then we highly recommend this plugin. Its price is fairly reasonable and justifiable considering the impressive attention to detail by the developers of this plugin.
1. Waves CLA-3A Compressor Review
Developed by Waves in collaboration with the renowned mix engineer Chris Lord Alge, the CLA-3A comes as a part of the CLA bundle and offers a unique sounding optical compression which definitely earns it a placement on this list of plugins.
The CLA-3A models the popular ’70s solid-state compressors which at the time offered better transparency when compared to the tube compressors. This gives it the tendency to perform better on vocals and guitars as opposed to the tube compressor modeled CLA-2A. The compressor is straightforward and simple to use, with a gain knob to adjust the output gain and a peak reduction knob to control the signal. Additionally, the users can switch between compressors and limiters just like traditional hardware.
- Perfectly models a widely popular compressor/limiter into a plugin that is easy to use
- CLA-3A has fast response times which makes it perfect to use for up-tempo music
- Sound quality is never compromised even at extreme settings
- Has both limiter and compressor for different applications
- Users can choose to add analog frequencies to the signal and get a choice of either 60 or 50 Hz frequencies
- 24 bit/192kHz depth resolution support for maximum quality
CLA 3A only works on Windows 10 for PC and macOS 10.13.6 or higher for Mac. It comes in VST/AU/AAX formats and only supports 64-bit devices.
The CLA-3A by Waves is the recommended plugin for users who need a straightforward Opto-compressor plugin that is budget-friendly and offers high-quality sound.
2. ADHD Leveling Tool (FREE) Review
Looking like a classic compressor, the ADHD leveling tool is a free plugin that does surprisingly well in capturing the sound of a classic compressor unit.
The developers of this plugin claim to have carefully engineered this plugin for optimum performance on vocals. It can also be used on instruments like guitar, bass, etc to duck down some peaks as well as add more punch and character to the mix.
- 4x oversampling which ensures the highest output quality
- Attack and release times are adjustable which is actually a plus point over most of the plugins discussed in this article
- The ADHD also offers a VU meter to control the attack and release times
- Peak reduction ratio is adjustable
The ADHD leveling tool has support for most Windows and Mac operating systems. It comes in VST/AU formats which makes it not available for Pro Tools. It supports both 32 and 64 bit systems.
Overall, this plugin does impressively well for a free plugin. It obviously is not up to par with plugins discussed on this list when it comes to emulating classic compressor sound signature. However, if you are looking for a free plugin that does a decent attempt at that, then the ADHD leveling tool is the go-to.
The Opto-compressor market is a pretty interesting and exciting market for producers and engineers. If you are looking for a plugin that sounds like your favorite optical compressor hardware unit, then you won’t have a hard time finding that. Many developers work closely with the hardware developers to bring you the classic, vintage Opto-compressor sound that has for long been a fan favorite.
In addition to that, multiple developers decided to add their own artistic touch to their plugin for enhanced abilities in terms of control and sound character and a lot of them turned out really impressive like the Brighton Opto Tube compressors and so on. This review compiles a list of what we think are the best optical compressors in the market. In short, you will not be disappointed by choosing to buy any of the plugins mentioned in this review.
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