Dumbler

The Dumbler target is a graybox family model, not a component-exact clone of a specific amplifier. Public references differ, and many Dumbler examples are custom-built or variant-specific.

Circuit Diagram

Diagram data lives in knowledge/models/amps/diagrams/dumbler.diagram.json5.

This JSON5 graph is a documentation and renderer artifact. It maps the clean, lead, and power-amp blocks to the current Rust emulation and deliberately avoids pretending to be a complete SPICE netlist.

Circuit graph

Dumbler graybox documentation graph

documentationrust-model

Extracted Topology

Input stage:

• 12AX7 / ECC83 first gain stage.
• 100 kOhm plate resistor target.
• 1.5 kOhm cathode resistor target.
• 1 MOhm grid leak target.
• 68 pF input cap target.
• Modeled as classic first-stage gain with asymmetric distortion.

Drive stage:

• 12AX7 / ECC83 second gain stage.
• 100 kOhm plate resistor target.
• 2.2 kOhm cathode resistor target.
• 25 uF cathode bypass target.
• 250 kOhm volume pot target.
• Feeds the tone stack and volume control.

Tone stack:

• Passive three-band low/mid/treble network.
• 250 kOhm low, mid, and treble pots.
• Bass cap target: 22 nF.
• Mid cap target: 2.2 nF.
• Treble cap target: 220 pF.
• Slope resistor target: 4.7 kOhm.
• Modeled as an interactive passive network with frequency-dependent attenuation.

Recovery and overdrive:

• 12AX7 / ECC83 recovery stage.
• 82 kOhm plate resistor target.
• 1.5 kOhm cathode resistor target.
• 25 uF cathode bypass target.
• Separate asymmetric overdrive path after the clean/tone path.

Phase inverter and power stage:

• 12AX7 / ECC83 long-tail-pair phase inverter.
• Push-pull fixed-bias class AB 6L6GC power section.
• Plate supply target around 420 V.
• Output transformer primary target around 5 kOhm.
• Negative feedback enabled.
• Presence control lives in the power-amp negative-feedback loop.

Modeling Notes

The Dumbler model should expose clean/lead path interaction and feedback-loop presence behavior, but it should remain a variant-aware graybox until measured hardware or a selected public reference variant is chosen.

Source Notes

Useful references include public Dumbler schematic archives, builder guides, and service notes. Do not commit scans or PDFs; keep only our extracted topology and confidence notes.