​​Neural DSP Quad Cortex vs. Fractal Audio Axe-FX 3

Digital FX was initially seen by some as a niche corner of the guitar-gear industry, but as time has gone on, the quality of these devices has gone on to rival and dare we say exceed, that of traditional analog equipment. Like the analog sector, the digital market has a few big name players that have stood out above the rest for some time, including Fractal Audio, and now Neural DSP.

In this KillerGuitarRigs Guide, we’ll be comparing the Fractal Audio Axe-FX 3 to Neural DSP’s Quad Cortex. We’re looking to find out whether the established Axe FX 3 is still worth your consideration over the runaway success that has been the Quad Cortex. For consistency, we once again used our Fender Jim Root Telecaster and a Vox AC30.


Fractal Audio released the Axe FX 3 in 2018 as a follow-up to their hugely popular Axe FX 2 model. At the time, Fractal Audio claimed the FX 3 had more power and more features than any other FX processor that had preceded it.

Fractal Axe-Fx III - Demo

Neural DSP, on the other hand, were widely regarded already throughout the industry for their plugins, but were yet to make a physical product until they released the much anticipated Quad Cortex. Since its release, it has really upended the digital FX industry, knocking some of the more established brands off their respective pedestals.

Check our full QC review here.

Quad Cortex - The most powerful floor modeler on the planet


Unlike the Quad Cortex, the Axe FX 3 is available as both a floor unit and a rack-mounted unit. The floor unit usually starts around $1,600, while the rack-mounted option is a more expensive proposition, normally retailing around $2,300. It’s also worth noting that Fractal Audio do not sell via third-party retailers like Sweetwater in the US and Canada. Instead, their products are exclusively available on the Fractal Audio website.

If you’re considering an Axe FX 3 rack-mounted unit, you’ll probably also be needing a foot controller. There are 2 options available, usually costing between $500 and $700.

The Quad Cortex is available from all good guitar retailers, and being a standalone unit doesn’t vary much in price. QC units can normally be found for around $1,850.


As far as usability goes, the Quad Cortex is a clear winner in comparison with the Axe FX 3. The Quad Cortex boasts a huge 7” touchscreen and a very simple layout, which really makes for a simple user experience. All core functions of the unit can be controlled from the touchscreen, and the stomp buttons feature rotary dial functionality which can also be used to scroll menus and select options. The display itself is bright and appealing, and the linear paths for your signal chains are really easy to read and understand.

The Axe FX 3 does feature a large LED display on both the floor unit and the rack-mounted option, although it isn’t touchscreen on either model. Me01aning we had to navigate the menus using the slew of buttons surrounding the screen. Button response was a little spongey, occasionally requiring a second push to acknowledge the selection. One neat feature of the floor model is the mini LCD displays by each of the stomp buttons. They give a quick ‘at a glance’ indication of what each button operates, which we found to be very useful.

Capture Quality 

Neural DSP Quad Cortex or Fractal Audio Axe FX3 || Form, Features, User Interface Comparison

Undoubtedly the biggest draw of the Neural DSP Quad Cortex is the Neural Capture profiling feature. The capture process itself is incredibly simple and unbelievably effective. Obviously, the QC is the clear winner when it comes to capturing, seeing as the Axe FX 3 doesn’t possess a capture feature at all. However, the Axe FX has been widely regarded as the best modeler on the market for years. So a comparison between a live capture and a quality model was definitely of interest to us.

As we did when we compared the QC and the Line 6 Helix, we’ve compared our Vox AC30, our AC30 profile on the Quad Cortex, and in this case the Axe FX 3’s Class-A 30W model (their AC30 clone).

We already had clean and dirty tones profiled on the Quad Cortex from our previous comparison and as we’ve alluded to previously, it’s a very simple, albeit loud, process. We found that in direct comparison, the Axe FX 3 is absolutely the closest digital model we’ve heard to the Quad Cortex’s profiles.

Despite being the best modeler we’ve come across, the Axe FX 3 still falls short of the authenticity of the AC30 tones we captured in the Quad Cortex. We couldn’t find any difference at all between the real amp and the QC. In a blind test, we couldn’t even tell whether we were hearing the Quad Cortex or the amp. We couldn’t say the same for the Axe FX 3. The sound was extremely similar, but the model didn’t give us the natural progression from smooth cleans to fat overdrive when pushed from low to high volumes.

As with other modelers, the Axe FX 3 can accept IR recordings, but it cannot profile amps and FX directly. Because of its time on the market, there are literally thousands of IRs available to download and use, but it’s a much more involved process than creating a profile with the Quad Cortex.

Available FX

The Axe FX 3 does come preloaded with significantly more FX than the Quad Cortex. The Axe FX 3 features 220 different FX and like other similar modelers, the FX are built into blocks that allow for the creation of custom signal chains. The out-of-the-box FX were all really good and didn’t require much of any modification. Although if you do need to tweak parameters, you have the option to do so.

The Quad Cortex has a more limited selection of built-in FX. Out of the box, they aren’t quite as good as those found on the Axe FX 3, although with some adjustment they are as good, and in some cases better. There are 70 preset FX across 32 different blocks with 4 parallel signal paths.

One of the weaker points of the Quad Cortex is the relative lack of aftermarket support. This is changing daily, however, with more and more third-party user profiles available for download. The AFX3 boasts thousands and thousands of available IRs on the other hand, largely due to its popularity and its extended time available on the market.

While the Quad Cortex doesn’t have such a large bank of built-in FX, it is capable of capturing analog pedals in much the same way as it can capture amps and cabs thanks to Neural Capture.

If a looper is important to you, know that the Quad Cortex doesn’t have this feature. The Axe FX 3 does have a looper, although it’s not the easiest feature to set up. Don’t consider the lack of a built-in looper a dealbreaker for the QC, as it takes analog pedals well. Both the QC and AFX3 can accommodate external expression pedals, and in fact, Fractal Audio manufacture 2 different pedals specifically for the AFX3 for guaranteed compatibility.

Playing Feel

Neural DSP Quad Cortex vs. Fractal Audio Axe Fx3 vs Line6 Helix | 1 Metal Song, 3 Amp Modelers

We found the playing feel of the Quad Cortex was a vastly superior experience to using the Axe FX 3. The AFX3 doesn’t feel bad, and in fact, plugged straight into a guitar, with headphone out, it feels a lot like being in a studio control room. Where it simply can’t compete is with the live feel. Using a QC provides a much more authentic pedal board type feel.

Not only is the physical feel preferable, but the more organic tone of the amplifier profiles really gives you the feeling you’re playing a real amp. And having the ability to get such accurate profiles of the world’s most famous amps makes the QC one of the single most versatile pieces of guitar equipment on the market. With the Axe FX 3, you’re getting some excellent FX and some great amp models, but there’s no escaping the fact that you know you’re playing a digital model of something.

Final Thoughts on the Neural DSP Quad Cortex vs. Fractal Audio Axe FX 3

This comparison is really a clash of the titans. What’s recognized as the best profiler on the market vs. a unit widely regarded as the best modeler. As difficult as it was to choose, there was a winner.

Because of the accuracy of the profiles, the incredible user interface, and the overall feel of using the Quad Cortex both in live and recording settings, we really believe it to be the better of the two units. The Axe FX 3 is still a great modeler and FX processor. If you have no interest in profiling and you’re simply looking for some excellent amp and FX models, it’s hard to beat. But it’s hard to ignore how much better the sound and feel of Neural Capture profiled amps and FX are than the digitally-modeled IRs.


  • Simon Morgan

    Simon is an Orlando based musician, but originally hails from Newcastle, England. He started playing bass and guitar in 1998, and played the local scene throughout his teen years before life got in the way. Favorite Genres: Blues, Classic Rock, and he’s not ashamed to admit - Emo