In the pristine world of digital audio, musicians, producers, and engineers are always looking for ways to “warm up” recordings. One of the best methods is to add a little saturation to the signal. Whether you want to make a snare drum sound less dry, add a little sparkle to a piano track, give a vocal presence and grit, or make an entire mix sound more energetic, a little saturation can go a long way. You can also go beyond subtlety and add crunch or distortion to a guitar, bass, kick, snare, piano, or any other instrument.
Although the term “saturation” originated with the effect of overloading analog tape, it’s now used to describe a number of different distortion types. One of the most prominent is the harmonic distortion created by running a signal through a hardware device with a vacuum tube in it.
You don’t have to track through an actual tube preamp or amplifier to get saturation, however. There are many plug-ins on the market that do a convincing simulation by modeling tube circuitry. What’s more, you can use them during mixdown, meaning you don’t have to commit to a particular amount of the effect—as you would if tracking through a hardware-based device—thus giving you more sonic flexibility.
In this roundup, I’ll focus on 11 plug-ins that are either designed solely for adding tube-style distortion or have it as a significant part of their saturation offerings. The products are presented in alphabetical order by manufacturer.
112DB REDLINE PREAMP ($129)
If you want to make an instrument or vocal sound like it was recorded through a tube preamp, Redline Preamp is an excellent choice. It excels at adding coloration to digital tracks. In addition to tubes, it can also emulate saturation from analog tape and analog consoles. Its effects are subtler than some of the other plug-ins in this roundup—you probably wouldn’t choose it to create super-saturated tones—but it accomplishes its mission authentically.
The heart of the plug-in is its three Tube bands—Tube Lo, Tube Mid, and Tube Hi—which govern how much of the effect is added in specific, user-adjustable frequency ranges. The Frequency knobs for the Lo and Hi bands set the range in which they operate—below the setting for Lo and above it for Hi. For the Mid band, the Frequency control sets a center frequency, and a Width knob sets the bandwidth.
You also get controls for Drive, which turns up input volume, and Warmth, which lets you choose whether to emphasize odd or even harmonics (the former adds punch and the latter warmth) to the signal. The Clip knob sets the threshold for soft clipping, which adds more crunch as it’s turned lower and more clipping occurs. Controls for Wet/Dry and Makeup Gain are included, and you can choose between stereo and mid-side operation.
ANTARES AVOX WARM ($69)
Although Warm is available separately, it’s also part of the Antares AVOX 4 vocal-tool suite. Ostensibly designed for vocals, Warm is also great on drums, guitars, and virtually any source.
You can switch it between two different tube-circuit emulations: Velvet, which models the sound of a tube preamp—and leans towards the subtle side, from a saturation standpoint—and Crunch, which is based on a tube guitar amp and, as its name suggests, can get quite a bit crunchy when the drive is cranked.
The plug-in has a graphic of a glowing tube in the middle, which lights up brighter as you add more gain to the circuit using the Drive slider. When Velvet is selected, it lights up blue. When Crunch is picked, it turns red.
Warm offers Input and Output sliders and a clipping indicator. It also features a button for a unique feature called OmniTube. As Antares explains it, most tube preamps work on the portions of the signal exceeding the clipping threshold, which are mainly transients. When Warm is in its default mode, that’s how it works, too. But when you switch in OmniTube mode, the processing acts on the entire signal, making the whole thing sound more crushed.
D16 GROUP REDOPTOR ($45)
Redoptor is a powerful plug-in with a host of features, a very low price, and a lot of EQ options. Based on its presets, Redopter appears to be aimed mainly at the EDM market, but its tube emulation can be used on instruments or voices in many styles. The input signal flows first into Redopter’s preamp section, where Lo Cut and Hi Cut filters let you tailor the sound before it hits the “tube” circuitry, and a Preamp Gain control that controls the amount of distortion.
The Tube section has a Bias control for adjusting the level of odd harmonics in the signal, and contains Tone and Brightness knobs. The next stop in the signal flow is a fully parametric EQ section, featuring bands for Low, Mid, High and Presence. In addition to an Output control, the master section has a Wet/Dry knob, which lets you adjust the ratio of wet to dry signal, providing further tweaking power and making it easy to back off a bit if you dial in too much distortion.
Redopter can create a wide range of effects, from slight break-up to super trashy distortion. I was particularly impressed with it on guitars, synths, drums and electronic percussion.
FAB FILTER SATURN ($154)
FabFilter plug-ins are renowned for offering power, options and ease of use, and Saturn is no exception. It offers several types of tube- and guitar amp-style saturation as well as tape saturation, bit-crushing and FabFilter’s proprietary Smudge algorithm. Two other key features are its modulation and multiband capabilities.
The default is single-band operation, but you can create up to six independent bands with frequency boundaries that can be easily dragged to the desired position. Even cooler, each band can have its own front-panel control settings, including the distortion type, Mix (wet/dry), Drive, Panning, Level, Feedback, Feedback Frequency, a 4-band EQ, and Dynamics.
The Dynamics feature lets you add expansion or compression to the signal, on a perband basis. The multiband capability makes it possible to, say, distort the heck out of the mid and high frequencies, but use a lighter setting on the lows, or vice versa. It’s quite flexible. In addition, you can switch between Left/Right and Mid/Side operation for each band. You can even solo or mute individual bands.
If you want to take your settings even further out, open the Modulation section, where individual parameters can be altered with five different types of mod sources including XLFO (LFO), Envelope Generator, Envelope Follower, an external MIDI Source, or an XY Controller.
MELLOWMUSE SATV ($79)
If you’re looking for quality saturation that’s super easy to use, you’ll like SATV. Not only does it offer a Tube algorithm, but also ones for Transistor, Transformer and Tape.
Three large knobs dominate its GUI. Drive controls the input gain. The harder you hit the input, the greater the saturation. Mix sets the wet-dry level, and Output governs the output level. A VU-style meter measures the output. Included are a global on/off switch and a phase reversal switch.
Saturation type is chosen using one of the four switches that sits below the VU meter. There are no onboard EQ options, but you can always insert an EQ plug-in before or after it if you need more sculpting power.
OHM FORCE OHMICIDE ($103)
This powerhouse plug-in can do everything from adding saturation to creatively mangling a sound beyond recognition. Like Redopter, it appears designed predominantly for EDM, but works great for other applications.
Its unique interface features four separate frequency bands, with user-adjustable frequency boundaries. You can select from one of multiple algorithms for each band, including tube sounds and myriad other distortion types.
Sliders at the bottom allow you to mix the signal of the various bands. Individual Wet/Dry knobs are provided, as are mute and solo switches, and a pannable feedback circuit.
On every band you also get a Gain control governing the amount of distortion, a noise gate, and dynamics control that lets you add compression or expansion.
Ohmicide has a unique control section called Melohman Mode, which lets you morph between presets using MIDI input. The time and smoothness of the morph is also controllable.
Once you master Ohmicide’s rather complex GUI, you’ll find the plug-in to be capable of an impressively wide range of saturation and distortion.
PLUGIN ALLIANCE SPL TWINTUBE ($199)
The TwinTube plug-in (which is also available in a UAD version) is based on an actual SPL hardware unit. It splits two different aspects of tube sound, Saturation and Harmonics, into separate processes that can be used together or independently. Activation buttons let you turn on or off each process.
The Harmonics process has two types of controls: a large knob that governs the intensity of the effect, adding presence as you turn it up; and two Harmonics Switches, which are used to set the fundamental frequency for the processing. The choices are 2 kHz, 3 kHz, 6 kHz, and 10 kHz. Doing quick comparisons between these or other settings is easy with the A, B, C, D switches. A single knob governs the amount of saturation.
TwinTube also offers signal-present and overload lights, an Output slider, a Power switch for turning the effect on and off, and a very cool feature called Mouse Wheel Control. If your mouse has a wheel, hover the cursor over one of the knobs or the slider and you can control the parameter with the mouse wheel.
I found TwinTube to be useful on a variety of sources, whether I was going for subtle warmth, crunchy saturation, or something in between.
SOUNDTOYS DECAPITATOR ($199)
Available individually or as part of the Soundtoys 5 bundle, Decapitator is a versatile processor that features two different tube algorithms, modeled from the Pentode and Triode settings on the Thermionic Culture Vulture hardware unit (see the UAD plug-in version later in this article). In addition, it offers algorithms based on the preamp in an Ampex 350 tape machine and input channels from Chandler/EMI and Neve.
The Drive knob controls the amount of distortion. Pressing the Punish button gives you a 20dB gain boost and kicks Decapitator into overdrive, greatly increasing the amount of distortion.
Other controls include Low-Cut and High-Cut filters, a Tone knob, and a Thump switch for dialing in a low-end boost at the frequency to which the Low Cut filter is set. Another handy feature is Auto gain. Turn it on and it automatically reduces the output level to compensate for increases in the Drive control, so the volume doesn’t change when you’re auditioning different levels of Drive. The ability to keep the volume constant makes it easier to realistically compare settings and avoid the “louder sounds better” effect, which can be misleading in any audio situation.
The big VU-like meter is called the Attitude Meter and is a visual indicator of the amount of Drive you’ve dialed in. A Mix control allows you to set the Wet/Dry level. Decapitator includes a large collection of presets, including instrument-specific patches for Drums, Bass, Guitars, Vocals, and more.
UAD THERMIONIC CULTURE VULTURE ($299)
An emulation of the iconic studio tube-distortion processor of the same name, UAD’s Thermionic Culture Vulture is capable of everything from a little bit of tube warmth to total sonic mayhem. The original unit was stereo, and you get the most options when you instantiate it on a stereo track or in a mono-to-stereo configuration.
The plug-in has two identical channels, each with three knobs: Drive, Bias, and Distortion Type. Drive controls the input gain. The higher you set it, the greater the distortion. The Bias knob on the original unit controlled the amount of current that was sent through the 6AS6 distortion tube.
If you look closely at the meters, you’ll notice that they’re measuring milliamperes, not VU, and reflect the setting of the Bias knob for each channel. Bias alters the saturation characteristics of the signal, making it thinner on lower settings and fatter on higher settings.
The third knob, Distortion Type, has three settings. Triode is the most subtle, and UAD suggests it for situations where you want warming without obvious distortion. Pentode 1 offers more saturation, and Pentode 2 is off the charts, creating heavy distortion. You can make any setting more extreme by clicking the Overdrive switch, which adds 20 dB of gain. Other controls on each channel include a highpass filter that can roll-off at 9 kHz and 6 kHz, Output Level, and Bypass.
Several global switches are included, as well as two that were not on the original hardware: Control Link and Mix. The latter is a wet/dry control and the former lets you link and unlink the two sides when running in stereo or mono-to-stereo configurations. When not linked, you can create some pretty dramatic stereo effects by using different settings on each side.
URS SATURATION ($99)
True to its name, this plug-in is all about Saturation, offering four different tube preamp algorithms as well as several that emulate transformer and tape-head saturation. Its controls are simple and intuitive. The Input knob governs how much level is coming in, and at higher settings accentuates the saturation effect. The Saturation knob turns up the intensity of the effect. The Wet/Dry slider gives you another variable for controlling the degree of saturation in the signal. The other two controls are a global on/off switch and a phase-reversal switch. (Saturation, along with SATV, are the only plug-ins in this roundup that offer phase reversal.) Near the top of the plug-in are meters for input and output, each with clipping indicators.
Just below the Saturation knob is a pull-down menu that lets you choose an algorithm. The tube algorithms are all based on Class A mic preamps. MotorCity emulates a mic pre similar to what was used in the Motown studio. Tape Machine re-creates a tube preamp from a ’50s-era tape machine. 1951 is based on a vintage tube mic preamp. German emulates a German-made tube pre used in Europe in the ’60s.
Also notable is Saturation’s exceptionally large collection of instrument- and vocal-specific presets. If you’re looking for ideas for settings, these make excellent jumping-off points.
WAVE ARTS TUBE SATURATOR 2 ($99)
The latest incarnation of Wave Arts’ saturation plug-in is an emulation of a dual-triode preamp with an EQ stage. The sounds are crunchy and warm, and the GUI is intuitive and fully featured. It can be run mono, mono-to-stereo, and stereo. Only one set of channel controls is available, but in stereo configurations, the effects are independently applied to the left and right.
Tube Saturator 2 has three distinct sections. To the far left is Saturation. A switch lets you choose between the 12AX7 or 12AU7 tube emulations. The 12AX7 emphasizes even harmonics and has a thicker sound with a slightly heavier saturation. The 12AU7 signal features both odd and even harmonics. The Drive knob increases the input gain, and as it does, drives the virtual tube harder, thus increasing saturation.
The next stage is the Baxandall-style EQ. It’s simple—Bass, Mid, and Treble knobs—but is extremely effective for sculpting the sound of whatever source you’ve inserted it on. It can even be used with the saturation turned off. The EQ can be switched between Pre and Post saturation or bypassed.
The Output section is equipped with a VU-style meter that measures output level, an Output level knob, and a Wet/Dry knob. In addition, you can switch on 2x Oversampling, which upsamples the signal to double the normal sampling rate to avoid aliasing distortion, and, according to Wave Arts, “more accurately simulate true analog circuitry.” The 2x Oversampling mode also doubles the CPU load: If you’re reaching the end of your processing power, you can run in normal mode, which also sounds really good.
ALL WARMED UP
All of the processors in this roundup provide realistic-sounding tube saturation effects. Making a buying decision comes down to your budget, what features you need, and whether you’re looking for more than just tube-distortion algorithms. Virtually all these plug-ins have a demo version available, so I urge you to try out a few and see which one you like.
I can say with confidence that once you start adding saturation to your tracks or on the master bus, you’ll wonder how you lived without it.
Plugin Alliance Black Box Analog Design HG-2
By the time you read this, a new saturation plug-in from Plugin Alliance should be available. It’s called Black Box Analog Design HG-2 and is an emulation of the hardware tube processor of the same name, with some added digital controls.
Individual level knobs for Pentode and Triode let you mix and match the sound of the two modeled 6U8A tubes. The Saturation control is used to dial in one of two 12AX7 simulations, whose sonic character can be changed with a three-position Saturation Frequency switch.
A three-position Calibration adjustment—Dark, Normal and Bright—affects the overall sonic character; and the Air switch is designed to add a little high-end sparkle. Moreover, Density lets you boost the pentode and triode tube-level simultaneously, with automatic compensation on the output stage.
Mike Levine is a composer, producer and multi-instrumentalist from the New York area.