Soundtheory Gullfoss Review (A Truly “Intelligent” EQ?)

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Soundtheory Gullfoss Review (A Truly “Intelligent” EQ?)
Soundtheory Gullfoss is a fantastic plugin for mixing and master engineers of all levels. As well as being incredibly effective, Gullfoss will assist you with your mixing and mastering decisions.
User interface
Ease of use
Identifies and fixes mix problems you weren't even aware of
Deals with the limitations of human hearing
Parameter buttons are clearly labelled and easy to understand
Not cheap
Seasoned professionals may not find it useful

Soundtheory Gullfoss is an automated adapted EQ plugin that is very effective when used on the mix bus and for recordings that require multi-mic setups.

Gullfoss helps you manage clashes between frequencies by analyzing the signal and deciding how to prepare the audio to minimize any confusion. Through the use of Soundtheory’s computational auditory perception model, Gullfoss helps you understand which audible elements are competing for your attention.

One of the biggest benefits of this plug-in is it allows for quick and precise fixes that would normally be impossible to repair. 

Soundtheory Gullfoss

Gullfoss is an easy-to-use tool for everyone from the amateur musician to the professional mastering engineer. Its clean user interface offers a set of basic parameters that can be adjusted to improve the clarity, detail, spatiality, and balance of a mix or recording in a matter of seconds.

View Price on Soundtheory

Soundtheory Gullfoss: Is It Worth It?

This EQ plugin can be a valuable tool when it comes to making smart decisions about your mixes. It paints a clearer picture of the frequency response so you can make informed mixing decisions.

It can also be a great tool for a young mastering engineer that wants to get a grasp of the basics.

Although the human auditory perception is limited, it can certainly be developed and trained to do what you need, and Gullfoss can be an ally in this process, as well as a great tool to attain better control of your audio.

Features (9/10)

Soundtheory Gullfoss is displayed as a frequency spectrum analyzer so you know what’s happing with great detail in the entirety of the frequency spectrum.

At the very top of the plugin, you will see some controls which perform the majority of the sound-shaping. These parameters are Recover, Tame, Bias, Brighten, and Boost.

To deal with problematic frequency overlap on your master bus, you can start using Gullfoss by bringing up the level of overwhelmed elements with the Recover control. On the other hand, you could also opt to bring them down by using Tame. Due to this relationship, you can think of Recover and Tame as balancing controls.

When using the Recover parameter the plugin will accentuate the higher frequency elements so you can really hear them in much greater detail.

However, with Tame, the sound becomes much airier, which can be used to your advantage if that’s what you’re after.

The next parameter is Bias, which will help determine how the plug-in reacts when it’s not immediately clear if Recover or Tame is the better option to use. For instance, you can add some positive Bias to reduce the effect of Tame.

The next parameter is Brighten. This is an overall tonality control that can be used to lift the top end, or reduce it if the source material is too bright.

By controlling the overall tonality of the EQ’s response, Brighten allows you to adjust the overall brightness whether you want to increase it or decrease it. This parameter is particularly useful for both the master bus and a variety of instruments, as we’ll see later.

Next up is the Boost parameter. Boost affects the tonal balance in a manner that reflects the way in which human hearing perception changes with increased loudness levels.

Its action is based to some extent on the Fletcher Munson Curve. Since our perception of audio is skewed to generally prefer louder sounds, Boost is an essential tool to help avoid overcompression.

Additionally, Boost also applies a dynamic effect on the EQ. Increasing the boost emphasizes the bass frequencies whilst cutting back on the mids. In other words, it creates the effect of louder audio, without actually increasing the overall level.

User Interface (9/10)

Soundtheory Gullfoss features a user interface that will be easy to understand for anyone who’s worked with a frequency spectrum analyzer before.

At first glance, it looks like your basic equalizer or analyzer plug-in that comes standard in most DAWs. However, even if you are new to digital audio and haven’t worked with a spectrum analyzer, the interface is clear enough to be intuitive and easy to use if you have a basic understanding of how frequencies work.

Gullfoss features some meters that let you know exactly what’s going on in a visual manner. The horizontal meters below in the frequency spectrum graph show how much the signal is being brightened or dimmed.

On the other hand, the vertical meters on the right let you know how much of the signal is being recovered or tamed. Both of these meters are very handy for their visual response that reinforces what you are hearing.

Despite its ease of use and streamlined user interfaced, keep in mind that it is important to take time to learn this plug-in and make it work in your favor over the long haul.

Sure, you can get some quick fixes out of this plug-in almost immediately, but it is always better to dig in a little so you can really learn how to best use Gullfoss in your mixes.

Ease Of Use (9/10)

Using this plugin is very straightforward. For the master bus, you can brighten the overall sound of your mixes if you wish, or you can scoop a bit to get more clarity.

You could also use Gulfoss on a variety of tracks and instruments, from acoustic guitar to basically any synth. Let’s use an acoustic guitar as an example of how this plugin works.

A common problem for many when recording acoustics is that the end result is not as bright as desired. Using conventional EQ will help to some extent, but this also brings up the pick and string noise. This is one issue where Gullfoss can really come in handy.

The obvious EQ parameter choice to improve the overall guitar audio is Brighten. It can help bring out those high mid to high frequencies, improving not only the overall frequency balance and tone of the instrument but also making it cut through and sit nicely in a mix.

Recover and Tame can also help you with bringing out the roominess of the acoustic guitar in case your mix is more sparse and the guitar needs to fill up more. On the other hand, Bias can help you tame those mid frequencies that can be troublesome in some situations, especially for busier mixes.

Now let’s take a piano sound and see how we can use Gullfoss to make it sound better. Let’s say the low mids are a bit muddy, which is a common problem for recorded pianos.

You can come in and clean it up a bit with the use of the Brighten parameter to tame the lower mids and allow the higher frequencies to come through with a lot more sheen and brightness.

As a result, this can help you hear the attack phase of the piano and have it sound much clearer and a bit airy. The end result is you get a more natural sound that is rich without being muddy.

Soundtheory Gullfoss

Gullfoss is an easy-to-use tool for everyone from the amateur musician to the professional mastering engineer. Its clean user interface offers a set of basic parameters that can be adjusted to improve the clarity, detail, spatiality, and balance of a mix or recording in a matter of seconds.

View Price on Soundtheory

Value For Money (8/10)

If we were to just look at the price, you could say that Soundtheory Gullfoss is not particularly cheap. However, this is a very unique plug-in with superior features that will be quite handy for many engineers and producers. This plug-in can help you significantly when making mix decisions in ways no other plugin can. It can also fix certain problems, saving potentially unrecoverable audio.

Considering what it does, and how it does it, the price is fair. You’ve probably heard the saying “you get what you pay for” many times. Well, Gullfoss is certainly not the exception, it just proves the rule.


Soundtheory Gullfoss is a very useful EQ plug-in with outstanding capabilities. This is a fantastic product for mixing and master engineers of all levels.

Besides being incredibly effective, it is also very easy to use and will help you with your mixing and even mastering choices.

For newer engineers, this eq plug-in can be a great ally in learning how to judge frequencies across the entire audible spectrum, whether it’s on your master bus or individual tracks.

Moreover, the Gullfoss plugin can help you develop a new way of dealing with the limitations of human hearing when it comes to making EQ decisions. This includes perceived loudness and Fletcher Munson Curves so that you can trust your ears a lot more in a variety of situations.

Because of its features, ease of use, streamlined and elegant user interface, and overall value, I recommend the Soundtheory Gullfoss for any engineer or producer out there.

And in case you needed further convincing, you can try this plugin completely free by visiting Soundtheory’s page and downloading. What’s not to like?

(If you’re after some quality free EQ plugins, check out 6 Of The Best Free EQ Plugins (Head-To-Head))