A preamp amplifies and shapes a small signal. A physical power amp provides power to a speaker and can add color, compression, and saturation. An amp head does not include a cabinet; a combo combines an amp and speaker. A complete amp block usually already has power-stage character. An additional Power Amp is optional, rather than a required block after every Amp.
Headroom is the space before distortion or limiting becomes significant. Sag imitates a supply-like response that softens when driven; Presence and Resonance affect that stage's high- and low-frequency character. Hardware Presence is often related to negative feedback. In a digital model, the knob's function follows its implementation, rather than automatically reproducing a physical circuit.
4×12 means four speakers of nominal 12-inch diameter, rather than one 48-inch speaker. Larger or more numerous speakers are not automatically bassier or better. Speaker model, cabinet, rear opening, interactions, and microphone all matter. Open-back tends to sound more spread out; closed-back tends to be more focused. These are tendencies, rather than rules for every cabinet.
A conventional IR applies a linear response through convolution. A cabinet IR can contain speaker, cabinet, microphone, and room characteristics. It does not respond with nonlinear amp breakup as an amp model does. NAM uses a trained network to model input/output behavior. A capture can be pedal-only, preamp-only, amp-only, or amp+cab; NAM does not always contain all of them.
| Model contents | Basic routing |
|---|---|
| Pedal-only | NAM pedal → Amp → Cabinet |
| Preamp-only | NAM preamp → Power Amp → Cabinet |
| Amp-only | NAM amp → Cabinet |
| Amp + Cabinet | That NAM → next effects; usually no additional cab |
| Cabinet IR | Amp → IR |
An additional cab after amp+cab applies cabinet color twice. In the app, metadata identifying amp+cab is used to disable the additional cab. A capture made at a particular setting does not guarantee access to every original knob. The app's NAM tone controls are post-model EQ, while Gain/Input changes the level entering the model. Check capture type, sample-rate compatibility, and calibration, rather than only the filename.
Concept references
- Fender — Gain vs. Volume
- Fender — The Presence Control Explained
- Celestion — IR Instructions
- Celestion — IR Convolution
- Neural Amp Modeler — Official project
- Neural Amp Modeler — Input calibration
Capture contents and routing
How does Amp + Cabinet differ from an IR?
- Contents
- Amp + Cabinet
- Additional cabinet
- Not needed by default
The amp and speaker response are already in one capture. A second cabinet is not needed by default. Adding one can over-filter the character.
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