Valve
Circuit-modeled two-triode valve preamp with passive tone stack, compiled ahead of time from its schematic by the Valve circuit compiler. Preamp only: follow it with a cab/IR. Experimental.
Parameters
| Parameter | Range | Default |
|---|---|---|
| Drive | 0 – 1 | 0.5 |
| Bass | 0 – 1 | 0.5 |
| Mid | 0 – 1 | 0.5 |
| Treble | 0 – 1 | 0.5 |
Overview
Valve is a tube preamp built from a schematic instead of a capture. The circuit is two 12AX7 triode gain stages with a Bassman-style passive tone stack between them: first triode, then the tone stack, then Drive, then the second triode. Axion solves that circuit while you play, so the controls behave like the pots on a real amp. They interact with each other and with how hard you hit the strings.
Valve is a preamp only. It has no power amp, output transformer or speaker. Put a Cabinet or Impulse IR after it, or the sound will be thin and fizzy.
Valve is experimental. Its sound may change in future updates, and rigs saved with it may not sound exactly the same after an update.
Controls
- Drive sets how hard the tone stack’s output drives the second triode. It is modeled as an audio-taper pot, as on a real amp. Low settings give a clean tone with a little warmth. As you turn it up, the second triode starts to compress and then clips.
- Bass, Mid and Treble are the three pots of a passive tone stack. Like a real passive stack, they cut rather than boost, and they interact. Changing Bass or Treble also changes how much mid you hear. With all three at 0 the stack is close to silent. Because the stack comes before the second triode, the tone controls also shape what gets distorted, not just the final EQ.
Every control runs from 0 to 1, the pot’s position from fully left to fully right.
Presets
| Preset | Drive | Bass | Mid | Treble | Sound |
|---|---|---|---|---|---|
| Warm Preamp (default) | 0.25 | 0.5 | 0.5 | 0.5 | Near clean, with soft compression and a rounded top end |
| High Drive | 1.0 | 0.7 | 0.3 | 0.8 | Thick, saturated crunch with scooped mids, a tight low end and a cutting top |
When you add Valve to a chain it loads Warm Preamp, so Drive starts at 0.25 rather than the 0.5 shown in the table above.
Tips
- Set the cabinet first. Valve sounds harsh straight into the outputs, and most tone decisions depend on the cab or IR after it.
- For a clean tone that still feels like a tube amp, keep Drive below about 0.3 and dig in with your pick. The circuit responds to playing dynamics.
- Use an overdrive pedal before Valve, with its own gain low and its level up, to push the triodes harder and tighten the low end.
- If the tone gets muddy at high Drive, lower Bass. Less bass going into the second triode tightens the distortion, which an EQ after the amp cannot do.
- Drive changes the output level a lot. Use the device’s output volume to level-match when you compare settings or switch between rigs.