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The cab sim rule

The one rule that fixes most “it sounds bad” problems, plus how to tell whether a capture already contains a cabinet.

Lesson 05 of 106 min
The short version

Cab sim on for anything full-range. Off for anything that ends in a real guitar speaker. Get this wrong and nothing else you do will help.

The rule

The IR Loader is a speaker cabinet simulation. A guitar speaker is a drastic filter — it rolls off everything above roughly 5 kHz, and without it a distorted amp signal sounds like a wasp in a tin.

So: if the thing at the end of your chain is full-range — headphones, studio monitors, an FRFR, front of house, your DAW — the Nano has to supply the speaker. Cab sim on.

If the thing at the end is a real guitar speaker, it’s already doing that job. Cab sim off.

How to turn it off

Turn Footswitch II past the last IR slot until no indicators are lit. That’s bypass.

There’s also a global IR bypass in the app’s settings, and since NanOS 2.1.0 you can bypass it per output — so one jack can feed a real cab while the other sends a cab-simmed signal to front of house. That’s genuinely useful and not widely known.

Watch out

Turning the IR off often causes noticeable clipping. The IR’s low-pass was doing level management as well as tone shaping, so removing it sends a hotter, full-range signal downstream. Pull per-preset capture volume down, and consider a Low-High Cut EQ in a post slot to replace the filtering.

Forum: Nano Cortex into front of amp · Forum: turn off cab sim

The double-cab problem

Here’s where it gets subtle, and where most bad-tone reports actually come from. Captures come in two kinds, and the device doesn’t reliably tell you which you have.

A capture taken from a mic’d cabinet has the cabinet permanently baked in. It cannot be separated. Run the IR Loader on top and you have two speakers in series — the result is what owners describe as “very boxed in”.

A capture taken from an amp head through a load box has no cabinet. Bypass the IR on that and you get the raspy, fizzy sound of an amp with no speaker.

The community’s own diagnostic, and the most useful sentence in the whole corpus: if the IR loader is off and it sounds bad, the capture probably doesn’t include a cab. If the IR loader is on and it sounds bad, the capture probably does include one.

Forum: amp + cab captures

Prefer amp-only captures

Where you have the choice, amp-only captures are the better buy. Neural DSP’s own position is that they’re easier to tame and give you more variation from the cab and IR settings — because you still get to choose the speaker, microphone and position.

An amp-and-cab capture is one fixed decision about all three, made by a stranger.

Which rig, which setting

The wizard below resolves every destination to concrete settings, including the warnings that matter for each one.

What are you plugging into?
Cab sim

Leave it on

You're feeding a full-range system, so the Nano has to supply the speaker.

Works well with no setup

The simplest way to use it, and the one most people start with on day one.

Hook it up
  1. GuitarINPUT

    Instrument cable

  2. HP OUTPUTHeadphones

    3.5 mm — bring an adapter

Set it up
IR Loader
On
Pick a cab you like; this is most of your tone.
Headphone volume
HP OUT knob on the rear
Independent of the LEVEL knob.
Effects
Prefer the (ST) stereo delay and reverb variants
Noticeably better in headphones.
Before you plug in

The headphone jack is 3.5 mm, not quarter-inch. This catches people out on the first evening.

Andertons spec sheet · Sound On Sound review
Once it works