Intro

What are your master-bus workflow needs? We asked this question to professional music producers that are under constant pressure and tight deadlines. Answers referenced the current industry-standard mastering suite and their frustrations with it: an overwhelming number of options, an apprehension about its automated features, and the nagging feeling that there’s better sound quality out there. We knew that Softube could help, and this is what Flow® Mastering Suite aims to achieve.

The Sound

With Flow Mastering Suite, you get the tools the pros use — tools from Weiss Engineering, Tube-Tech® and Chandler Limited® that really were previously only available to professional mastering engineers — in a robust mastering environment full of tailor-made mastering chains, or flows, that fit every need.

The Flows

In psychology, the concept of “flow” refers to being in a mental state of immersion. This is when time slows down, you are deeply focused, and your body and mind are one with your work. In Flow® Mastering Suite, we aim to let the music producer stay in that flow state, in the production mindset. To work faster, save time, and get the best results possible, while enjoying the process.

We believe that the tools we use in audio production should be designed in a manner that enables the operator to trust their own decisions, motivative them to learn, give them opportunity to practice, and to make them sometimes leave their comfort zone to grow. In Flow Mastering Suite, you always see what the tools are doing, there are no black-box processing or secrets. While working, you are guided by contextual text and visualizations that aid you in what to look and listen for. We teamed up with professional mastering engineers, like Jonathan Wyner; grammy-nominated mastering engineer, author, and professor of music production, to ensure the highest level of quality in sound and workflow. Their expertise and insights have been captured in what we call “Flows”: Custom built signal chains that uses high-level macros to control the parts of the chain, along with contextual information and visualizations.

Flow Designers

Jonathan Wyner
Niels Nielsen
Magnus Lindberg
Joakim Jarl

First use: Play the loudest portion of your track and click Calibrate Input to adjust the input level to -16 LUFS, which is the level that the Flows are calibrated for. Switch between the different Flows and familiarize yourself with the Flow controls. Listen carefully to the result and keep in mind that the contribution of each Flow control might be subtle. To audition the changes, click Gain Match Input, and toggle Bypass to easily compare before and after without difference in level.

On Mastering...

Mastering as a creative activity was introduced in the 1950’s. For the following decades mastering was much about transferring audio from tape to vinyl and making sure that the audio reproduction was consistent and sounded as good as possible. With the introduction of digital audio in the 1980’s, the options for increasing dynamic range increased, and with that loudness increased. Today, digital distribution over the internet has influenced the mastering activity, where one must consider the changing requirements of the distribution platforms.

Also, the expectation on the work of the music producer, from artists and labels, has become that work-in-progress should sound as close to the finished product as possible throughout the production process. As a music producer, you might not be making the final mastering decisions. But when sending your track to a label or an artist, chances are that you’ll need to deliver your track quickly, with sound that is as clear, punchy, and yes – sometimes as loud sound as the competition. Flow Mastering Suite is built to give you the confidence to reach those goals. It also lets you to really work with the details and shape your craft, so that you can be the one that delivers that final master.

User Interface

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Input and Output Panels

The input and output panels are included in every Softube plug-in. To read more about extra functionality of these, please see the Extended Features manual.

Input Volume: Sets the input level to the Flow. The Flows are designed to operate with an input level that measures -16 LUFS when the music is loud.

Calibrate Input: Automatically sets the input level to -16 LUFS. You need at least 4 seconds of music before you can get an accurate reading of the input level. When loading a new instance of Flow Mastering Suite, or if your sound level exceeds -14 LUFS for more than 4 seconds, Calibrate Input will blink to notify you that you should adjust your input level.

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Input level should always be around -16 LUFS.

A/B/C/D: Switch between different settings (states).

Gain Difference Metering

The orange gain difference meter measures the difference between the LUFS-S on the input and output and shows it as a meter. This makes it easy to manually or automatically gain compensate for the Flow.

Gain Match Input matches the LUFS-S on the input to the LUFS-S on the output to make it easy to compare the difference in sound. Use the Bypass button in the Flow to get a glitch free comparison.

Gain Match Target sets the output level so that the LUFS-S level gets set at the target level (-14 by default). You can set the target level by dragging the orange slider to the right side of the meter.

Gain Match Reset resets the output level to 0.0 dB.

Pre Fader Metering lets you monitor the output level before the output gain. This is useful if you use Gain Match Input to A/B compare the audio, but you still want to see what the final LUFS level will be. After comparing, press Gain Match Reset to reset the output level to 0 dB.

Output Volume sets the level of the output. This should typically set to 0.0 dB when you bounce your audio file. If you need 0.1 or 1.0 dB headroom, set the Output Volume to -0.1 or -1.0 dB.

Target Level sets the target level for the Gain Match Target function.

Reset LUFS click on the LUFS read-outs beneath the meter to reset the LUFS levels.

You probably want to compare the audio before and after Flow, and the easiest way to do this is by clicking Gain Match Input to level match the input and output, and then use the Bypass functionality in Flow to get a glitch-free smooth bypass. When you are ready to bounce your audio file, press Gain Match Reset to reset the levels to 0.0 dB.

Controls Panel

The Controls panel at the top consists of the Flow Controls, which are unique for each Flow, along with the Flow Selector, with which you can select a different Flow. Just beneath the Flow Selector you find buttons to engage a smooth bypass, the low latency mode as well as turning off the help texts for the controls and plug-ins.

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Flow Selector

Click on the name of the Flow to open the Flow selector, where you can choose between many different Flows for different purposes.

Flow Controls

A Flow Control is a very powerful master control that can adjust several parameters in several plug-ins with a single turn. Hovering a control will give you a description of its intended use, as well as an overview of which plug-ins and parameters it controls.

Hovering a Flow Control will open the Flow guides and also mark out which plug-ins it is controlling with a blue line underneath each controlled plug-in.

Apart from adjusting the control, there are many more tricks to it:

Click the control to cycle through each plug-in that it controls.
Right-click the control to immediately open the Flow guide.
Hover the control to open the Flow guide to read about its function.
Hover the control to see which plug-ins it controls.
Hover the control to automatically see the corresponding visualization.

The control is color coded to easily understand which type of function it has:

Blue is tonal changes, such as EQ, but could also be de-essing or multiband compression.
Yellow is dynamic changes, typically compressors, but not limiters.
Green is stereo image and widening processing.
Red is level, the final limiter that brings up the level of the song.
Gray means that the control no longer corresponds to the settings of the individual plug-ins, if you for instance adjusted a parameter in a plug-in directly.

Parameter Linking

It is possible to override a Flow control by adjusting an included parameter directly from its plug-in interface. If this happens, the Flow control will turn gray. Adjusting the Flow control again will in turn override this setting.

If you wish to exclude a parameter from the Flow control, it is possible to do so by clicking the parameter name in the list of Linked Parameters in the Flow Guide.

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If you open the Flow guides from the Flow control, you can easily see which plug-ins and parameters that are controlled from that control. If you on the other hand open the Flow guides from the plug-in, you will see which Flow controls are controlling that plug-in.

Flow Guides

Turns the automatic Flow guides on/off. On by default, and will appear whenever you hover a Flow control or plug-in.

Low Latency

Switches the high latency algorithms, particularly in the Weiss plug-ins, into low latency versions. The Low Latency version will not sound identical, but is intended to be used when tracking or recording.

Visualizations

Flow Mastering Suite uses three different visualizations to show that changes to the audio. In Auto mode, the visualizations will change depending on which Flow control you are adjusting, but it is possible to override by clicking either Frequency, Stereo Image, Gain Reduction or Loudness.

Auto

Automatically choose the visualization, depending on whether the control is tonal, dynamic or limiter, or is adjusting the stereo image.

Frequencies

Shows a frequency analyzer of the output (blue in foreground), input (blue in background) and the differences between these (orange). The orange curve can be interpreted as an EQ curve but is looking at the complete tonal change from input to output. All different types of gear will change the tonality, not only equalizers, but also compressors and saturators. For example, if you add a lot of harmonics, you will see an increase in orange curve in the high mids.

The frequency analyzer can be customized by selecting the following options:

In/Out/Diff: Shows or hides In/Out/diff curve visualizations.

Mode: Fast, Slow (default), Hold Average, Hold Peak. Sets the update speed of the analyzer.

Channel Conf: Input/Output (default), Left/Right or Mid/Side.

Tilt: Tilts the frequency spectrum 0 dB (default), +3 dB (pink noise tilt) or +6 dB (brown noise tilt). With a +3 dB setting, the frequency spectrum will be flat for a pink noise signal, which corresponds better to how our ear perceives frequencies. A lot of mastering engineers and mixers prefer to view the frequency spectrum with a +3 dB tilt.

Smoothing: Sets the frequency smoothing of the spectrum, from completely off, to 1 semitone (1/12 octave, default) up to 2 octaves smoothing.

Block Size: Sets the frequency resolution and update speed of the spectrum.

Stereo Image

Shows a goniometer on the output of the signal chain.

Gain Reduction

Shows the individual gain reduction from each Flow control, as well as the combined gain reduction.

Note that some compressors might report a lot of gain reduction, but because they are used with parallel compression, or band-limited compression, the actual compression can be a lot less that what’s indicated by this meter.

Loudness

Shows real-time tracking of the evolution of LUFS and dynamic range over time in two different visualizations. The Dynamic Range is expressed as Peak to short-term Loudness Ratio (PSR) and the LUFS shows short term LUFS. On the left-hand side, the views also show distribution of all LUFS and dynamic range measurements on your track. The marker can be dragged to set a reference level for both LUFS and dynamic range.

How to use the Dynamic Range visualization: Drag the marker to the desired dynamic range level. Values below the marker means that you have less dynamic range and that your track might sound too compressed. A rule of thumb is to keep dynamic range (PSR) above at least 8. Or, you can check the dynamic range for a reference track by using Flow Mastering Suite, or by using another PSR meter.

The Loudness visualizations can be customized by selecting the following options:

Show Target Marker: Shows or hides Target Marker.

Show LU Distribution: Shows or hides distribution of LUFS and dynamic range on the left-hand side of the visualization.

Show True Peak: Shows or hides True Peak measurements over time (only in LUFS visualization).

Reset on Play: Clears the visualization when hitting Play in your DAW.

Plug-ins Panel

At the bottom of the user interface are the included plug-ins. Click on a plug-in to open it, click and drag to view all plug-ins, and hover a plug-in to read information about it.

Disable turns off the plug-in and saves CPU. This is not intended to use as a “smooth” way of bypassing a plug-in.

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Using Flow® Mastering Suite

There are a few considerations regarding the use of the product, as well as some technical terms and guidelines for mastering. Below are some thoughts on how to approach using the product, while giving some basic background for limiting, output levels, metering and dithering.

What is limiting?

Limiting is a safeguard for audio peaks not exceeding a set level. It prevents unwanted distortion and clipping that occur when the audio signal exceeds the system's maximum level, 0.0 dBFS (decibels relative to full scale).

What is True Peak limiting?

Even when using limiting as a safeguard, so called inter-sample peaks can occur after digital-to-analog conversion (DAC) or when converting to lossy formats like MP3. In this conversion, peaks that occur between the sampled points of a digital audio signal (inter-sample peaks) can cause distortion if they exceed 0 dBFS. True peak limiting is used to ensure that these peaks do not exceed a specified threshold. The drawback with using True Peak limiting is that you might not be able to achieve a master as loud as without True Peak limiting. But, using different limiting algorithms can also be an aesthetic choice: Factors include choices in level of transparency, aggressiveness, more or less pronounced transients, or artifacts like pumping or even distortion.

What is True Peak metering?

True peak meters (complying with ITU-R BS.1770 and EBU R128 standards) are used to measure inter-sample peaks. Oversampling techniques are used to predict and measure the signal’s peak levels more accurately than standard peak meters. The level is referred to as dBTP (decibel True Peak).

Should you care about True Peak limiting?

Many professionally mastered albums contain inter-sample peaks, while still being considered “good sounding”. One conclusion from this might be that the peaks in themselves may not be an issue, it’s more about if they are noticeable in a bad way or not. Another thing to consider is what you are aiming to achieve. There is a trade-off between “loud” and “clean”, and intersample peaks are a part of this equation. If your goal is “loud”, then you might need to have a few inter-sample peaks above 0 dB. See Recommended Output Levels for our take on how you should use Flow® Mastering Suite in this regard.

Recommended Operation

Here are some common situations where mastering or master-bus treatment is done, and our recommendation for setting output level and handling inter-sample peaks:

Processing the master-bus to get a feel for what the finished track might sound like: There’s no need to change any settings for the final limiter plug-in or the metering. The limiter will keep the peak signal below 0.0 dBFS.
Pitching a song that you want to sound “close-to-finished” to an artist/label or sending it for feedback: There’s no need to change any settings for the final limiter plug-in or the metering. The limiter will keep the peak signal below 0.0 dBFS.
Preparing a final master for a streaming service: There is much discussion about what the approach should be here, but if you want the recommended best practice, it’s this: refer to the peak and loudness target guidelines for the service. This will inform you how to set your output volume. The current guideline for Spotify is -1.0 dBTP as a safety margin, but these guidelines tend to change over time. Turn on True Peak Metering, check for True Peak clipping and adjust the Output level to adhere to the guidelines. If you want an even more safe approach regarding inter-sample peaks, turn on True Peak limiting.
Preparing a final master for CD: Keep the default settings in Flow® Mastering Suite. The recommended best practice here is to master to -0.1 dBFS. If you’re concerned about inter-sample peaks, turn on True Peak Metering, check for True Peak clipping and adjust the Output level. If you want an even more safe approach regarding inter-sample peaks, turn on True Peak limiting.
Preparing a final master for vinyl: This is an art in itself and it’s best to consult with literature or someone knowledgeable on the subject for best practices.

How to turn on True Peak Metering

To activate True Peak metering on the input and/or output panels – go to settings (cogwheel) in the Flow® Mastering Suite plugin window and select True Peak for the peak meter in the Input Panel and/or the Output Panel.

How to turn on True Peak Limiting

The Flows handle limiting a bit different depending on the sound that the Flows are built to achieve. For this reason, True Peak limiting might be turned on or off by default. To change the setting:

If the final limiter is Weiss DS1-MK3 or Weiss Compressor/Limiter, go into the Options panel (Options button on the Weiss DS1-MK3 and the “>>” button on Weiss Compressor/Limiter) and choose Limiter Type 2.
If the final limiter is the Weiss MM-1, there is no option to choose True Peak limiting.

Oversampling

Compared to running in 44.1kHz, the Flow® Mastering Suite plugin utilizes a 2x linear-phase oversampling for processing. Internally, fast compression/limiting or peak clipping algorithms, as well as True Peak detection, will oversample to 4x. The level of oversampling chosen is carefully selected to provide the best sound quality, lowest latency, and lowest possible CPU usage.

Dithering

Our recommendation is to use the built-in dithering in your DAW. This is to make sure that there is no processing happening after the dithering, which will undo the effects of the dithering. If you still want to use dithering within Flow® Mastering Suite, this can be done by choosing a Flow that has either Weiss DS1-MK3 or Weiss Compressor/Limiter as the final limiter. Go into the Options panel (Options button on the Weiss DS1-MK3 and the “>>” button on Weiss Compressor/Limiter) and choose type of dithering you want. In this case you must make sure that the Output volume is in the Output panel is set to 0.0 dB, otherwise the effect of the dithering will be lost.

Loudness Metering

The metering system in Flow® Mastering Suite fully complies with the ITU-R BS.1770 and EBU R128 standard, including True Peak metering when activated. The different types of metering can be changed in settings (cogwheel) both for the Input Panel and for the Output Panel.

Credits

Pelle Serander, Patrik Holmström, Björn Rödseth – Framework programming
Anna Pohl Lundgren, Arvid Johnsson – GUI programming
Arvid Rosén, Niklas Odelholm, Kim Larsson, Fredrik Jansson, Anton Eriksson, Thomas Andersson, Mattias Flygare – DSP programming
Niklas Odeholm – Product Design
Jonathan Wyner, Niels Nielsen, Magnus Lindberg, Joakim Jarl – Flow Design
Niels Nielsen, Johan Bremin, Emanuel Enbäre – Quality Assurance
Stefan Aronsson – Customer Insights
Torsten Gatu – Product Management
Johan Toverland – Project Management

Before we start, let's get this out of the way

Flow® Mastering Suite

Flow^® Mastering Suite