Captures, Profiles and Models: How Modern Amp Modelers Copy an Amp
Every modern modeler promises "the sound of a real amp", but they get there in two very different ways. Knowing the difference helps you choose a unit and get better tones from the one you have.
Approach 1: modeling the circuit
A component model recreates the amp's circuit in software: the preamp tubes, the tone stack, the power amp and how they interact. Fractal (Axe-Fx III, FM9, AM4) and Line 6 (Helix, and the Agoura models in Helix Stadium) are the best-known examples.
What it is good at
- Every knob works like on the real amp, across its whole range.
- You can change things a real amp would not let you change, such as the tube type or the power amp sag.
Limits
- It models a design, not your specific amp with its own tubes and age.
Approach 2: capturing a real amp
A capture (or profile) measures a real amp at one setting and recreates how it responds. You plug the modeler into the amp, it plays test signals through it and learns its sound.
- Kemper calls this profiling. With the Profiler MK 2 series, Kemper announced Liquid Profiling, which adds the original amp's gain and tone controls to a profile so it behaves more like the full amp.
- Neural DSP calls it Neural Capture, on the Quad Cortex, Quad Cortex Mini and Nano Cortex.
- IK Multimedia calls it AI Machine Modeling, in TONEX software and hardware such as TONEX Board.
- Neural Amp Modeler (NAM) is a free, open-source platform for training and playing AI models of amps and pedals. Thousands of free community models are shared online.
What it is good at
- It can sound extremely close to one specific amp, including its quirks.
- You can capture rare or borrowed amps and keep them.
Limits
- A capture is accurate at the setting you captured. Turning the gain far from that setting is less faithful, which is the problem Liquid Profiling and similar features try to solve.
What this means in a low tuning
Low tunings are where captures and models are tested hardest: a tight low end at high gain is difficult for any amp.
- Capture with the boost you play with. If you use an overdrive in front of the amp, include it in the capture, or add the same boost in front of the capture.
- Check the low string. Play a fast palm-muted riff on the open low string. If it smears, lower the gain before adding more bass cut.
- Compare at the same volume. Louder always sounds better, so match levels before you choose between two captures.
A quick test is the gallop riff in B minor at 120 BPM in Drop B: if the gallop stays clear, the patch is tight enough for most metal.