Neural DSP Nano Cortex

Want to take your valve amp sounds on stage without breaking your back? The Nano Cortex makes capturing and delivering those tones quick and easy.

Founded in Finland in 2017, Neural DSP offer a range of software and hardware emulations of guitar‑related hardware, including amps, speakers and effects. Their debut hardware product, the groundbreaking Quad Cortex, catapulted them into the limelight in 2021. We’ve since reviewed and been impressed by a number of their machine‑learning‑based plug‑ins, not least the Archetype series, which emulate the signal chains of specific artists.

They’ve now released a new hardware device, called the Nano Cortex, and it’s both more compact and more affordable than the Quad Cortex. As well as offering access to a range of machine‑learning‑based amp and effects emulations, it features the company’s proprietary Neural Capture technology, which uses neural networks to learn (capture) and digitally replicate the sounds of amps, drive pedals and any combination of drive pedal, amplifier, loudspeaker and microphone.

Hardware & Software

The Nano Cortex is housed in a stylish, compact enclosure. One of the first things you’ll notice is that there’s no screen here, with visual feedback instead provided by four rows of five LEDs on the top panel, but it’s also very much designed to be used with the associated control app, of which more below. The top panel carries two momentary buttons, rotary gain and EQ controls, and twin footswitches, all of which feature LED indicators, and, as on the Quad Cortex, each footswitch also incorporates a continuous rotary encoder.

The sounds are based on ‘captures’ and these are stored, along with any effects, as presets. When a preset is recalled the two LED rows above footswitch 1 display its bank and slot position. Above footswitch 2, the upper row of LEDs indicates the active effect slots, with the LEDs of the pre‑capture effects glowing orange and those of the post‑IR effects blue. A blinking FX LED indicates that the Amount control is active on that effect. Footswitch 2’s lower LED row displays the active IR slot, and that’s selected using that footswitch’s encoder.

Each of the front‑panel control knobs is surrounded by a segmented LED ring displaying its settings within the recalled preset. Of course, since these are pots rather than continuous rotary encoders, those settings may or may not coincide with the knobs’ current physical positions when you recall a preset. By default, the LED ring jumps to the position of a control as soon as its knob is moved, but you can change this using the app to require the knob to pass through the current setting before a change is made.

The Nano Cortex can function as a USB audio and MIDI interface — and even allows you to capture the sound of your DAW’s virtual amps to take on stage.

The rear panel carries a series of quarter‑inch balanced TRS jacks, one for the mono instrument input, two for the mono/stereo output, and one for an expression pedal that doubles up as a MIDI I/O port. There’s also a ground‑lift switch, a mini‑jack headphone output with a volume control, and a USB‑C port. The USB port serves several functions. First, it allows the Nano Cortex to function as a 4‑in/3‑out 24‑bit/48kHz USB 2 audio and MIDI interface for Mac, Windows, iOS or iPadOS devices, which means you can record straight from this box into your DAW. If connected to a computer, the Nano Cortex can also be programmed to send, over USB‑C, up to 12 Program Change and/or continuous controller messages per footswitch press and per preset on recall, which could prove very interesting for some users. And when connected to a Mac or Windows machine’s USB‑C port the Nano Cortex can draw its power from the computer, though it’s worth noting that it cannot be powered from older USB A ports; if connecting that way, you’ll need an external 600mA, 9‑12 V DC power supply. When not connected to a computer, you can use such a pedal‑style PSU, or a 5V/2A USB‑C charger or power bank.

The side‑panel Capture input can accept instrument or mic signals.On the right‑hand panel, you’ll find a dedicated combi XLR/TRS Capture Input socket, along with an adjacent switch to apply a 26dB boost. This is used during the amp or drive‑pedal capture process to receive the output from the mic/amplifier or drive pedal being captured; the second (right) output on the rear serves as the send from the Nano Cortex to the device you’re capturing.

While you can obviously select the loaded presets using the hardware controls, there’s also Neural DSP’s Cortex Cloud app for Android and iOS devices. This app, which communicates with the hardware over Bluetooth, really is essential. Not only does it let you download firmware updates, captures and cabinet IRs, but it also lets you upload your own captures to the Cortex Cloud, and manage the onboard preset, capture and IR libraries. What’s more, it gives you remote access to the Nano Cortex’s settings, including the front‑panel controls and the parameters for all the effects slots. You can also use it to adjust the volume of an active capture (‑24dB to +12dB) and save the result in a preset. For loaded IRs, the app offers comprehensive manipulation, allowing you to select (for factory IRs only) from one of five mics and six centre to edge‑of‑cone positions, and (for both user and factory IRs) to invert polarity, adjust level and apply fully variable high‑ and low‑pass filters.

Prefab Sounds

I’ll get to the user‑capture side of things below, but straight out of the box you can use the Nano Cortex as an amp, cab and effects simulator. It comes pre‑loaded with 25 amp‑only captures (20 for guitar and five for bass). These are organised in five banks of five and directly accessible using top‑panel controls. The quality of the factory content is good and most user bases are covered, from clean, through blues‑y breakup to high‑gain metal, but you can also store up to 256 captures in an onboard user library. I suspect few of us will be tempted to create so many captures ourselves, but many factory and user‑generated captures are available through the Cortex Cloud app — more, in fact, than anyone’s likely to need in several lifetimes! For loudspeaker cabinet IRs it’s a similar story, with direct access to five of the 10 pre‑loaded factory IRs, as well as the ability to store and load a further 256 IRs, whether downloaded or self‑created.

The signal path consists of seven slots. Two (Adaptive Noise Gate and Transpose) are pre‑capture effects slots. Next comes the Neural Capture slot, which can hold drive pedal, amp or amp‑and‑speaker captures, as you prefer. Then there’s the IR loader, followed by three post‑IR effects slots: chorus, delay and reverb. The order and content of the five effects slots can’t be changed, but the app does allow quite deep editing of the three post‑IR effects. In addition, you can activate or bypass each effect individually from the front panel, and can set how much of each active effect is applied to the post‑IR signal.

All of the available parameters for each of the five effects can be adjusted and saved on a per‑preset basis using the Cortex Cloud app. The top panel’s Amount control also gives you direct access to a single operational parameter: noise reduction level on the noise gate; ±12 semitones on the pitch‑shifter; and dry/wet mix for each of the three post‑IR effects.

Taking the effects and processors in turn, despite having only a noise reduction level control, the adaptive noise gate is very effective. I particularly like that it doesn’t continuously open and close around the cutoff level — it just keeps on closing until a new note or chord is struck. It was more than speedy enough for me, though I’m not sure that it will be quite fast enough to satisfy djentists.

I have to say that the decision to follow the noise gate with pitch transposition puzzled me at first — but I think I get it now! Control‑wise, there’s a wet/dry mix setting, a ±12‑semitone pitch‑shift, and separate high‑pass and low‑pass filters. The transposed pitches always tracked flawlessly, but in practice the high‑ and low‑pass filters will probably turn out to be more useful, as they can be included in any preset either individually or together, the latter arrangement meaning you get a fully‑variable band‑pass filter.

The post‑IR effects trio begins with Neural DSP’s model of the Boss DC‑2W chorus pedal. The DC‑2W itself, in Standard mode, is an emulation of Boss’ original 1980s DC‑2 Dimension C, while in its SDD‑320 mode it emulates Roland’s legendary SDD‑320 Dimension D. To my ears, Neural DSP have nailed the DC‑2W emulation, particularly its updated SDD‑320 four‑mode, six‑sound switching. The app gives you access to the wet/dry mix, a variable Drive parameter that adds a bit of weight to proceedings, control over the output level (to compensate, if necessary, for the Drive level), the SDD‑320’s front‑panel switching, and the Standard/SDD‑320 mode switch.

Next comes Neural DSP’s emulation of the warm, vintage tonality of a BBD (bucket‑brigade delay) type analogue delay. Through the app, you have control of the wet/dry mix, delay time, feedback, high‑ and low‑pass filters, modulation rate and depth, stereo width, drive and ping‑pong off/on. And, lastly, there’s the Mind Hall reverb, which emulates the sound of Lexicon’s famous 224 digital reverb, and ranges from the tight ambience of a small room right up to the seemingly endless reverb of a monstrous hall. The app gives you control over the wet/dry mix, decay time, pre‑delay, damping and high‑ and low‑pass filters.

The Capture Process

Clearly, then, you have access to plenty of sounds right off the bat, but for many guitarists it’s the prospect of capturing the sound of their own amps, cabs and pedals that will be the biggest draw. The neural network that Neural DSP use for this is said to have been designed to perceive sound in a similar way to human hearing, so as to produce natural‑sounding captures. Something else that sets it apart from the competition is the sheer simplicity and speed of the capture process — after initial calibration, it takes only around five minutes from start to finish, and it can be done without a computer, an Internet connection or even the Cortex Cloud app. That said, the app does make the capture operation much slicker...

To get started, you plug your guitar into the Nano Cortex’s input and your monitor speakers into output 1L, or headphones into the headphone output. Then connect the Nano Cortex’s 2R output to the input of the target device, and feed the target’s output into the Capture input. That target output would be a mic, if you’re planning to capture an amp and speaker combination, of course. The Nano Cortex doesn’t supply phantom power — it expects a passive dynamic mic, which is the classic choice for cabs — but you could use a capacitor mic if you have a separate phantom power supply. If you’d wish to capture just the amp, without the speaker, the best output would be from either a reactive load box, or a DI box that can be connected between your amp and speaker.

The capture setup for the author’s miked‑up Fender Vibrolux Reverb combo, with both the hardware and control app in use.

With everything hooked up, a press and release of the Capture button puts the Nano Cortex into Capture Calibration mode, and automatically switches the app to its first capture screen. Then you play your guitar to check the levels, adjusting the gain of the capture signal (using the front‑panel control or the app) until the gain control’s LED ring turns green, and then you’re ready to go. Now, when the capture process starts (more on that shortly), you’ll discover that the audio signals produced by the Nano Cortex are highly dynamic. It was through a process of trial and error that I discovered the ‘best’ way to calibrate the signal for my setups, which was to thrash my guitar’s open strings, and turn up the gain until louder (not the loudest) sounds just turned the LED ring green.

Having done that calibration, just press and hold the Capture button for three seconds: the LEDs will turn off, and then start re‑illuminating, one segment at a time, until the capture process ends. Note that if you’re intending to capture a 50‑100 Watt combo or stack at high volumes using a mic, this process can get very loud. If in the same room, I’d highly recommend ear protection... and you might also consider giving neighbours of a nervous disposition advance warning!

Footswitch 1’s LED turns green when the process is over, indicating that your new capture is active. Using the footswitch, you can then toggle between the capture and original return signal, to compare the sounds. If happy with the capture, you can store it in a Bank slot (replacing the slot’s existing contents) or in the pedal’s User capture library.

On Test

The first thing to say about my experience of using the Nano Cortex is that the quality of the onboard presets is good, and I could simply enjoy the experience of playing through it. In that context, I found it liberating not having any screen calling for my attention, though the Cloud Cortex app is very useful, not least since it gives you so much more control over the effects settings. The app’s really easy to use too.

Personally, though, I was more interested in the amp‑capture side of things. Again, this can be done using the Nano Cortex as a standalone device, but it’s definitely slicker with the app. The first amp I chose to capture was my favourite, and one which I know very well: the THD Univalve, which has a highly detailed, dynamic sound, and is capable of resolving the differences between different types of input and output valves. I set this up using its built‑in Hot Plate load box DI output to send the capture ‘return’ signal back to the Nano Cortex. After hitting upon the ‘trial and error’ approach to calibration I discussed above, I obtained my first successful capture — and, to my great delight, it turned out to be all but indistinguishable from the actual sound coming from the Univalve’s DI output. The only difference was that the capture sounded ever so slightly smoother overall but, honestly, that was no bad thing! Importantly, the Univalve’s playing dynamics were faithfully reproduced, and I’d be more than happy to record or gig with this capture. I’ve since created a number of captures of this and other amp setups, and they’ve all been similarly successful.

I’ve used amp‑capture systems before, but the ease and speed with which this successful capture was obtained really has opened up a whole new way forward for me.

I’ve used amp‑capture systems before, but the ease and speed with which these captures were obtained is truly impressive, and I have no intention of sending the review unit back — it really has opened up a whole new way forward for me. While I have no intention of abandoning my valve amps either, or my collections of IRs and amp‑modelling hardware and software, I now plan on capturing my favourite sounds from each of them into the Nano Cortex to give me instant access to them all, whenever and wherever I am.

Diving deeper into the IRs, the phase, level and high‑ and low‑pass filtering available for the factory cab IRs (each of which contain five microphones and six mic positions, so a total of 30 IRs per cabinet) proved extremely useful in matching them to individual amp/pedal captures before saving both capture and cab in a preset. Also, the level of control over the effects offered by the app really opened up their potential, allowing me to tailor the three post‑IR effects, in particular, to my requirements and taste.

Setting up the Nano Cortex as an audio interface for Reaper on my iMac was issue‑free, with the Nano Cortex showing up as a 4‑in/3‑out USB interface. Recording is simply a case of connecting a guitar to the Nano Cortex’s input, creating a mono audio track in your DAW to record input 1 (the dry DI guitar signal) and a stereo track set to record inputs 3+4 (the processed signal from the Nano Cortex), arming the tracks and hitting record. If you want to re‑amp the dry track, simply route it to output 3 (which feeds the input of the Nano Cortex), arm a stereo audio track set to record inputs 3+4, and hit record. It’s easy enough, but to make life easier still Neural DSP have developed templates for some of the major DAWs, including Reaper.

Capture For Masses?

My abiding impression of the Nano Cortex is of a remarkable pedal that offers exemplary sound quality and exceptionally speedy and highly accurate captures. It’s incredibly easy to use, whether you’re working standalone or using the apps to embellish the experience. That said, if you ever do find yourself stuck, there’s a very good interactive online manual.

To put it another way, with its combination of pre‑loaded top‑flight captures, high‑quality modelled effects, and its audio interface and re‑amping capabilities, Neural DSP’s Nano Cortex really is the gamechanger that I’ve been waiting for. It lets me capture all my favourite valve amps, drive pedals, amp‑modelling software and hardware presets, and store them along with my favourite cab IRs in one compact, portable package — and for a price that won’t break my bank manger’s heart. It even has a built‑in tuner... So, if you’re looking for a high‑quality AI‑based amp capture and replay device, I’d encourage you to check out the Nano Cortex. Having done so yself, I can assure you that this one isn’t leaving here!

Information

£499 including VAT.

neuraldsp.com

$549

neuraldsp.com

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