Your first fifteen minutes
Power, cable, input level, a sound. The shortest path from box to playing, with the two things that stop people at the first hurdle.
Set the input level before you judge a single sound. Everything you think about the amp models is downstream of a meter nobody tells you to look at.
Power it from the mains, and only the mains
The Quad Cortex wants 12 volts at 3 amps. That is a great deal more current than a typical pedalboard supply delivers on one outlet, so most isolated supplies simply cannot run it. Check the current rating rather than the voltage — the voltage matching is what fools people.
There is no battery option and no USB power. Use the supply in the box until you have specifically confirmed an alternative can deliver 3 A.
It is safe to pull the plug on a running unit — Neural say so directly — though they still recommend shutting down via the power button first. You will not corrupt your presets by cutting power.
Quad Cortex Wiki: FAQThe USB cable is not the one you own
The Quad Cortex uses USB Type B — the big square printer connector. Not USB-C. If you also own a Nano Cortex, that cable is USB-C and will not fit.
You do not need USB to make sound, so this is not a first-fifteen-minutes blocker. It becomes one the moment you want Cortex Control or multi-channel recording.
USB
USB Type BMulti-channel audio interface, and the link to Cortex Control on the desktop.
Type B — the square printer connector, not USB-C. The Nano Cortex uses USB-C, so owning both does not mean owning the right cable. On Windows you also need Neural’s USB Audio Driver installed before Cortex Control will talk to the unit.
Gridleak: read off the unit · Quad Cortex User Manual 4.0.0Plug in, and pick your output honestly
Guitar into INPUT 1. Then decide where the sound is going, because the answer changes what you should build:
- Headphones or an FRFR speaker — you want the cab block on. The modelled cab is doing the work of a real one.
- Into a real amp — you want the cab block off, and you want the amp block gone too. Lesson 07 covers this properly.
- Front of house — OUT 1/L and OUT 2/R are the balanced XLR pair. That is what the engineer wants.
- A quarter-inch destination — OUT 3/L and OUT 4/R, and mind the cable: a TS cable there costs you 6 dB against a TRS one.
Set the input level before anything else
Swipe down from the top of the screen, open I/O Settings, and select your input. Watch the IN 1 LEVEL meter while you play a little harder than you normally would. You want it to just tickle the red, or sit fractionally below.
Start at 0 dB. The unit is designed to take a hard-strummed humbucker there without clipping, so for most guitars this is already correct and you are only confirming it. If a hot pickup buries the red, pull the level down until it stops.
This takes ninety seconds and it is the difference between forming an opinion about the amp models and forming an opinion about your own clipping.
Input level is global. It is not saved per preset and no scene can change it, so if you swap between a hot humbucker guitar and a weak single-coil one mid-set, this stage is a compromise for one of them. Set it for the hottest guitar you will play.
Quad Cortex Wiki: Gain Staging · Quad Cortex Wiki: Setting the Input LevelHow to get hereSwipe down from the top of the screen, tap I/O Settings, then select INPUT 1.
IN 1 LEVEL — start at 0.0 dB
This is the default and it is correct for most guitars. Neural build the input to take a hard-strummed humbucker here without clipping, so for a lot of players this screen needs nothing at all. Only move it if step 3 says to.
The meter — play, don't guess
Play a little harder than you normally would. Not your hardest, not a polite test strum — a bit above your real playing. That is the level the input stage has to survive all night.
Aim to just tickle the red
Peaks should touch the top of the amber and barely graze the red. That is “just below clipping”, and it is the check — not a rival opinion to 0.0 dB.
Buried in the red? Come down
If a hard strum sits inside the red rather than grazing it, lower IN 1 LEVEL until it stops. Digital clipping does not soften the way analogue clipping does — there is nothing musical waiting up there.
This setting is global
It is not saved per preset and no scene can change it. Set it for the hottest guitar you will play, then make up the difference on quieter guitars with a gain block inside the presets that need it.
Find a sound and a tuner
Presets live in setlists — the Factory setlist is where to start. BANK UP and BANK DOWN move you through banks; A to H select within one.
Hold TEMPO for the tuner. That is printed on the chassis, which makes it the one thing on this device you can rediscover without a manual.