Safe Headroom, Filter Types, Limit Controls, and other DSP features in SoundID Reference explained.
In this article:
Safe Headroom
The Safe Headroom feature in SoundID Reference ensures there is no gain-staging-related clipping (distortion) as a result of applying calibration. Clipping can occur when certain frequencies are boosted and the digital audio peaks above 0 dB. With Safe Headroom enabled, the Output Gain is lowered to avoid clipping. While Safe Headroom can be disabled and the Output Gain slider maxed out, it is recommended to have it enabled at all times.
Safe Headroom is available in both the SoundID Reference standalone app and DAW plugin, and the Safe Headroom amount differs for each calibration profile, as it corresponds directly to the highest peak in the correction curve. For example, if the highest peak in the calibration curve is 12.4 dB, then the Safe Headroom amount will also be -12.4 dB. To avoid any volume jumps when switching between profiles with varying Safe Headroom amounts, a volume matching logic is in place: when switching from a profile with a greater Safe Headroom value to a profile with a smaller value, the previously used Output Gain will be retained.
Note: Clipping also depends on the audio content being played. While there might be no risk of clipping with the audio content currently being played (with Safe Headroom disabled and Output Gain maxed out), clipping might still be introduced later on when playing audio that is rich in the same frequencies that are boosted in the calibration curve. Disable Safe Headroom at your own risk only.
Safe Headroom for Multichannel
When used with Multichannel profiles in the SoundID Reference DAW plugin, Safe Headroom is split into channel groups for additional user control, and features two functionality states: Specific and Unified.
- Specific: Safe Headroom value is different for each channel group. Each channel group's Output Gain is limited by the Safe Headroom amount of the highest peak of the calibration curves in the channel group (dictated by the calibration curve with the highest correction peak in the group). The master Output Gain slider has a Safe Headroom value that matches the lowest channel-group Safe Headroom value for the calibration profile.
- Unified: Safe Headroom value is the same for all channel groups. The Output Gain is limited by the highest calibration curve peak in the profile (the largest calibration curve boost out of all channels/calibration curves). Same as the stereo implementation of "Enabled". The master Output Gain slider matches the Safe Headroom value of all channel groups for the calibration profile.
Filter Types
There are three Filter Types available for the DSP engine in both the SoundID Reference DAW plugin and the standalone app of SoundID Reference: Zero Latency, Mixed, and Linear Phase. All three Filter Types differ audibly and have individual technical aspects: phase response, pre-ringing, latency figures, and processing power required.
The exact latency figures for each Filter Type can be viewed under the Latency menu, and the phase response changes can be viewed by selecting the Phase curve under the Frequency response curves menu.
Note: Only the Zero Latency filter is available for multichannel calibration. Mixed and Linear Phase modes are not available when using multichannel profiles in the SoundID Reference DAW plugin.
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Zero Latency mode ensures 0 ms of internal processing, so it is perfect for live tracking/real-time monitoring as it doesn't introduce any additional latency. It is also the most efficient of the three Filter Types, requiring the least amount of processing power. However, it does introduce phase shift. This can be viewed in detail in the Phase response curve (click on the Frequency calibration curves dropdown menu, and select the Phase curve to be displayed). The exact phase shift depends on the applied calibration profile, but usually stays within the ±30° band, so it’s barely audible.
Note: True zero-latency performance can only be achieved using the SoundID Reference DAW plugin format. Additional latency is introduced by the virtual audio driver chain when using the standalone app on a system-wide level, due to the SoundID Reference virtual audio driver's relationship with the operating system audio engine.
- Mixed mode keeps the phase response changes to a minimum while also retaining low latency figures. It is essentially a sweetspot between Zero Latency and Linear Phase and Zero Latency modes.
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Linear Phase retains the phase response unaltered. There is no phase distortion introduced, and the phase response remains unchanged with calibration Enabled/Disabled. To ensure this, a latency of 20-50 ms is introduced to the signal. This mode requires the most processing power out of the three filter types.
Note: Linear Phase mode is subject to audible pre-ringing. Pre-ringing is a backward echo effect; it sounds like a sucking type of sound. It is expected as a natural consequence of using a linear filter, and is most noticeable on transients, particularly audible on individual drum tracks.
Note: Near-zero latency performance can be achieved with the SoundID Reference standalone app, using the APO and ASIO to ASIO drivers mode on Windows, more details here: [WIN] Audio driver types in the standalone app.
Recommended workflows
There is no definitive correct or incorrect way of using the Filter Types - settings will depend on your individual mixing and monitoring needs and preferences. However, for a simple and stable workflow (at least while getting familiar with the software), we recommend using Zero Latency or Mixed modes for the majority of the mixing process, then switching to Linear Phase towards the end of the mixing process, to check for any phase-related issues.
Listening Spot
To compensate for stereo imbalance in your room (speaker calibration), the Listening Spot feature calibrates the overall channel volume imbalance and channel delay to ensure perfect volume and time alignment at the listening position, with sub-millisecond precision. The Listening Spot calibration values are determined during the speaker measurements and then available as a separate feature in the SoundID Reference standalone app and DAW plugin.
- For stereo profiles, a single toggle switch (Adjust to listening spot) applies both the volume and timing calibration.
- For multichannel profiles, two toggle switches (Adjust to listening spot balance and Adjust to listening spot delay) apply volume and timing calibration separately.
Stereo image imbalance is a common issue in most speaker setups, and there can be various reasons for it: speaker placement, furniture layout, room symmetry, and other room properties, as well as the individual speaker build consistency, volume/gain, and other settings dialed in on the speakers/hardware manually. The software will show the amount of imbalance and compensate for it accordingly. Listening Spot can be disabled, but it is recommended to use it and is enabled by default.
Important: When Listening Spot is enabled, it is normal for the output VU meters to appear uneven, especially if there is a significant volume imbalance between channels. This happens because the software intentionally adjusts the digital signal of quieter channels to ensure that the physical sound at your listening position is balanced.
Note: The human brain naturally compensates for stereo image imperfections in your room — this is a well-documented phenomenon in psychoacoustics. As a result, the applied calibration may feel unusual and even wrong at first. It often takes some time for your ears to adjust, especially if you have been monitoring in the same room for a long time. We recommend spending several listening sessions with reference tracks with the SoundID Reference app to help your hearing adapt. Once you feel more comfortable, try mixing a new project with the Listening Spot calibration enabled. When you review your mix on different playback systems outside your usual setup, you will likely find that the stereo image translates more accurately than before.
Limit Controls
The Limit Controls feature can be used to set limits for the frequency range and maximum boost/ceiling for the calibration, and it is a handy tool to "tame" the calibration in case it is causing unwanted side effects. Limit Controls settings are available for speaker calibration only, and the configuration is available for three separate parameters.
The changes applied can be viewed by selecting the Limits curve under the Frequency response curves menu.
- Calibration (max boost/ceiling): Normal (12dB) (default setting), Reduced (6dB) & No boost (0dB). The Safe Headroom adjusts accordingly based on the setting used. If "No boost" is applied, Safe Headroom will stay at 0 dB.
- Max low frequencies: Reduced, Neutral (default setting), Extended, Aggressive.
- Max high frequencies: Neutral (default setting), Extended, Aggressive.
The default settings are recommended, but adjustments can be made based on your room and speaker properties and personal preference. For example, smaller speakers with 4-5 inch bass woofers will be physically incapable of producing any large bass calibration boosts, so it might be a good idea to use less aggressive "Max low frequencies" settings to avoid bass distortion. Similarly, your room and speaker properties (or personal preference) might allow for more aggressive settings, too.
Note: More detailed control calibration curve adjustments can be dialed in using the Custom Target feature.
Target Modes
The calibration Target Modes in the SoundID Reference standalone app and DAW plugin adjust the frequency response target curve to suit your monitoring needs and help you achieve the best mix translation for your target audience. There are four Target Modes available: Flat Target, Dolby, Custom Target, and Translation Check.
See the video tutorial below for a full walkthrough on how to use Target Modes.
Flat Target
The Flat Target is based on the SoundID SR (Studio Reference) standard, and sets a completely neutral (flat) frequency response target for speaker-based playback systems across all audible frequencies as perceived by the listener in the listening position. For headphone calibration, the Flat Target is designed to emulate neutral-sounding speakers in a treated room (matches the Flat Target between speakers and headphones).
Dolby
The Dolby target calibrates audio to the Dolby Atmos Music curve target. Users with Dolby Atmos-compatible setups will want to use this mode primarily. Use this mode to move sounds in a 3D environment with better precision. This is a fixed Target Mode and won't allow for further adjustments.
Custom Target
Custom target allows users to make real-time adjustments to the target curve, depending on their workflow and preferences. With options for Shelf, Bell, Q, Gain, and Freq. Range, it features everything you'd expect from a parametric EQ, and lets you tailor the calibration curve to your individual monitoring needs. This feature is available for both headphone and speaker calibration and functions identically in the SoundID Reference standalone app and DAW plugin.
To access Custom Target, select an output preset and navigate to Target Modes > Custom Target. Filter values can be changed by either dragging the points or by manually turning the frequency/gain knobs to boost or cut specific frequencies. The calibration range can also be adjusted with the calibration range curtains, and can be used in combination with the EQ adjustments:
- Limit low and high freq. range calibration using the left/right sliders.
- Limit the mid-range calibration by flipping the active calibration zone (click the invert logo at the top of the frequency curves window when the curtains are selected).
Custom Presets
Any given Custom Target configuration can be saved as a Custom Preset. These presets can be renamed, duplicated, or deleted. Using the left and right arrows in the Custom Target header allows for quick switching between the Custom Presets you have created.
- Navigate to Custom Target > Custom Presets (˄).
- Click on Save as a new preset to create a new Custom Preset.
- Click on Save this preset to rewrite an existing Custom Preset.
- Name your file and choose a custom destination folder if needed.
- Save the file - it will now show up in the Custom Presets list.
Note: Changes made to the Custom Target presets are not saved automatically. Save them as shown above before switching to a different Custom Preset, or before quitting the app/plugin. Changes made will have to be saved to a new file. Currently, the existing file can not be overwritten.
Custom Presets are saved as .json files in these directories by default (unless a custom location is used). These files can be transferred to a different device. This way, the Custom Presets can always be retrieved, used between the standalone app and DAW plugin formats, and the favorites shared between colleagues and friends:
macOS
~/Library/Application Support/Sonarworks/SoundID Reference/Sonarworks Projects/Custom Target preset
Windows
C:\Users\your username\AppData\Local\Sonarworks\SoundID Reference\Sonarworks Projects/Custom Target presets
Translation Check
Translation Check provides a library of 25 predefined targets allowing you to check your mix in various devices and listening environments (cars, smartphones, in-ear headphones, and more), simulate specific industry-standard speaker models, and even simulate other headphone models from the Sonaworks headphones profile database.
Testing your mix on various devices gives you a competitive edge and saves time. For instance, check how your kick drum and bass sound on a smartphone or popular in-ear headphones, or do a critical car mix check without bouncing your audio or going to your car. Translation Check can be especially useful if you find yourself creating audio content for a specific device class, as you can tailor the sound for the best translation on this particular device.
- Cars: three car sound system tier targets, from harsh-sounding/entry-level to luxury/with subwoofers.
- Headphones: A-pods, In-ear average, MDR-AA111, Momentum, Over-ear & On-ear average, P7, QC3x, Snd-sport.
- Laptops: Latt 14", MB Airy 13", MB Professional 15".
- Smartphones: Smartphone Average.
- Studio speakers: Mixcubes, NS11.
- TVs: Japanese 46" TV, Korean 60" TV, TV Average.
- Other: B&K 1974 Speaker Target, X-Curve, Tilt (Tilt 2 dB, 4 dB, and 6dB).
Translation Check is available in both the SoundID Reference DAW plugin and the standalone app. To load a Translation Check target, proceed as follows:
- Create an output preset and load a calibration profile.
- Select Translation Check in the Target Mode options.
- Load one of the available target simulations.
Notice the "ⓘ" informative descriptions available to help you understand the added value of each target. You can also click on the "♡" (heart) icon to add a target to the Favorites section.
Note: Translation Check target (or any other Target Mode) will be saved as a part of the Preset automatically. Additionally, a red "CHK" label will appear next to your Preset for a quick visual indicator that a Translation Check target mode is active.
Headphone simulations
To make sure your mix translates well on a specific headphone model, you can simulate a rough representation of any SoundID Reference-supported headphone model on your own calibrated setup:
- Select your output preset, and navigate to the Target Mode panel.
- Select Translation Check > Headphones > Add a headphone profile
- Select any of the available headphone profiles to simulate it.
You can delete any of your simulation targets, or click on the "♡" (heart) icon to add them to your Favorites.
Note: When simulating Individual Headphone Calibration profiles, the individual L-R correction curves of the simulated profile will be summed and applied as an average.
Virtual Monitoring targets (spatial simulations)
Translation Check also features 10 spatial simulation targets (Cars, Laptops, Smartphones, and TVs) developed exclusively for Virtual Monitoring on headphones, unlocking the full potential of the Virtual Monitoring Add-on (VM). While the regular Translation Check targets only simulate the frequency response of a certain device, the VM targets contain additional data to provide a full spatial simulation of the given target on headphones.
For example, activating the Smartophone or the Car target with VM is enabled will simulate the physical sensation of holding a phone in front of you, or sitting in a car physically - all while monitoring on headphones. Learn more about VM here: Virtual Monitoring Add-on.
Note: While VM is enabled, only the 10 dedicated spatial simulation targets will be available in Translation Check. To make the other targets visible again, disable VM.
Frequently asked questions
Is there a phase response correction feature available?
No, the Listening Spot feature only aligns individual channel delays of the speakers based on phase response measurements to ensure the simultaneous arrival of sound signals from all speakers to your ears. Depending on your system, this often brings significant improvements in terms of sharper sound stage and overall clarity.
A separate Phase Correction feature might be implemented in the future; however, there is currently no ETA available for it.
Is latency affected by the time alignment (Listening Spot)?
The Zero Latency filter in SoundID Reference refers to our core DSP engine running in the zero-latency DSP filter mode. With time alignment enabled ("Adjust to listening spot delay") for soundstage correction, those delays will be added on top of the full-cycle latency (reported in the Latency overview at the bottom-left corner of the plugin).
Time alignment added delay figures will depend on the individual setup/calibration profile, and the exact values will be shown in the Listening Spot section.
6 comments
SoundID lowers the monitor output even with safe headroom off, and output all the way to 0db.
Why is that? is there a way to make sure what comes out of the audio interface is the same when refference is enabled or not?
Hello Filippos Iliadis ,
Thank you for reaching out!
I have created a support request regarding the issue encountered, it would be best to look into this in greater detail.
As per the Audio interface and the calibrated output, it would be best to test if it's enabled by using a more pronounced target curve such as a Car stereo or MacBook speaker to see if the calibration is taking place.
I hope this helps!
I'm glad I checked here - as this is a serious issue for us running the Multichannel SoundID on a major film project. The setup was so easy btw - a real pleasure dealing with such innovative and progressive method of implementation.
Currently any Protools session we run when started or restarted requires the SoundID plugin to be deactivated - then re-activated - otherwise the Level is literally around 10dB low as described above by Philip (with the Safe Headroom Disabled), without exception.
I'm running a Mac Studio / Sonoma / PT 2024.3.1 - but note this was also happening on my iMac running Monterey and PT 2023.12.1.138 (?).
I have a question, I need to have my room calibrated at 74, 76, 79 db, usually before calibrating I set my speakers to 79 db and then calibrate, and I put some marks on the master of the monitoring control. but the sound id reference drops the safe headroom limiter at the output by 12 points,
how can I make my room stay at 79 db without taking the safe headroom to 0?
What meaning do those 12 dB that result from the measurement have?
Would it be better to calibrate, leave the limiter where it is at those -12 points of the sage headroom and then increase the volume to the master monitoring control?
Or would it be better to raise the speakers to 91 db, calibrate and leave the -12 points of the safe head room limiter below?
THIS! What Juan Montoya asked is something I and probably a lot of others NEED to know.
Specifically about whether to raise our monitoring output to compensate for this drop in loudness, which in my case is -6.1dB, so in essence, I'd be raising my interface's output by 6.1dB.
I'm a music producer who's been at this for 12 years now. I and several other bigger producers and engineers have now started using SoundID Reference after discovering just how much of a difference it makes on our devices, especially our ATH M40X's and M50X's, and how much better our mixes have gotten since using this software.
However, we've also been deep diving into the technicals and the specifics to ensure that we're getting everything done CORRECTLY.
I even ended up remaking the entire correction spectrum in Pro-Q 4 with speed set to very fast and resolution at maximum, with range set to 120dB. However, I was using a far more accurate measurement as my reference when making this, which ended up being the wrong choice, given that my test correction was different from the Reference one, so now I just have a preset called HELL that doesn't serve much of a real purpose, but oh well.
The point is: We the producers, the engineers, all of us, we take this kind of thing extremely seriously, and we need answers.
So, Sonarworks, if you guys could PLEASE respond to Juan's comment left in July of last year, that would be really great, and please let me know when you do, so that I get a notification about it!
Especially about whether to raise his output by 12dB, or 6.1dB in my own case. I don't have anything that can measure what happens to the output waveform after sonarworks, as I'm using the systemwide version, with the injection into my output device, and using a virtual-type ASIO to send my DAWs audio to that output. So there is no reliable way for me to actually look at the waveform and what happens to it AFTER my interface. Though I do have an oscilloscope, so I might try that.
Thanks.
@Brent Burge This is a known issue. I noticed you already wrote to us and we’ll update you once a fix is available.
@Juan Montoya Safe Headroom is a feature that ensures that no gain-staging related clipping as a result of applied calibration takes place, even on the most sensitive frequencies. The level is based on the measurements and can be influenced by the room properties (reflective surfaces, etc.).
This might take some getting used to when using the SoundID Reference plugin in DAW since the level will go up once the plugin is bypassed for rendering. For this reason, you might want to add some metering plugins before SoundID Reference to keep track of the real level of the mix, or simply hard-bypass the plugin every once in a while during the process to hear the actual mix level. Additionally, using a dedicated monitoring bus for the plugin might be helpful for a more permanent/template-based levelling approach to your projects.
To answer the question on a dedicated monitoring level - yes, if your production workflow requires monitoring at a specific dB level, simply increase the overall level on your output device for the amount of Safe Headroom used.
Making changes to your room can ensure a less severe Safe Headroom level.
@Christoffer Rønaasen FYI, see the comment above. When using the plugin, make sure SoundID Reference is the last in the audio chain. As a test, you can of course play around to see the waveform. Using the standalone app is a good solution too, if the added latency is not an issue.