For
Tube-amp builders who want a real Studio: design any tube regulator from spec, simulate, diagnose and export.
You will learn
- Compare every tube-only regulator topology on a shared bench
- Master cold-cathode VR physics, stacking and ballast sizing
- Design series + error-amp regulators with predictable Zout, ripple and stability
- Diagnose live faults (oscillation, sag, hum, no-strike) with the interactive assistant
- Export Markdown reports + SPICE netlists wired to Ampera's Koren tube models
Before you start
Power supply & rectification
Time & level
45 minAdvanced
Next step
← Reference
WarningNumbers should match, not be identical
Reproducible bench
Every measurement in this studio comes from the same bench. Reproduce it locally and your numbers should match within a few percent — anything wider is an interesting discovery.
Bench specification
- Mains
- 60 Hz / 117 Vrms ±10%
- Transformer secondary
- 325 Vrms each side of CT
- Rectifier
- silicon-bridge (drop ~10 V)
- Filter topology
- CLC
- C1 / L / C2
- 40 µF · 10 H · 40 µF
- Choke DCR
- 100 Ω
- Nominal load
- 50 mA
- Load sweep
- 10–100 mA
BOM — concrete parts
| Designator | Part | Notes |
|---|---|---|
| T1 | Hammond 369AX | 325-0-325 Vrms / 200 mA secondary, 115 V primary |
| BR | silicon bridge 1N4007×4 | Or 5U4 / GZ34 in the purist variant |
| C1 | Mallory CGS401T450X4L | 40 µF / 450 V can — reservoir |
| L | Hammond 193J | 10 H / 100 Ω DCR / 200 mA |
| C2 | Mallory CGS401T450X4L | 40 µF / 450 V can — smoothing |
| R_load | Vishay PR02 wirewound | Sized for 50 mA at the rail under test |
| R_bleeder | Welwyn AC05 | ≥ 2× computed dissipation, in series if > 250 V each |
Measurement chain
- Oscilloscope: Rigol DS1054Z (or any 50 MHz 4-channel) with 100× HV probe.
- DMM: Keithley 2000 (or any 6.5-digit) for V_DC.
- FFT analyser: scope FFT for ripple, plus optional Audio Precision APx515 for < 1 µV.
- Variac on the primary for soft-start and line-reg sweeps.
- Electronic load: B&K Precision 8542 (or DIY MOSFET) for load-reg sweeps.
Reproduction protocol — five reference numbers
- V_raw at 50 mA load: expect 440 ±10 V (cap-input, near V_peak).
- Ripple on the V_raw rail feeding the regulator, at 50 mA: expect ≈ 800 mV pk-pk at 120 Hz (the course's reference figure for ripple-attenuation math).
- Filter mode: cap-input (CLC, reservoir cap first). No critical current — V_raw stays near V_peak across the whole load range; the sag just grows with current.
- Line-reg sweep ±10 % mains: V_raw shifts by ±40–45 V (V_raw tracks V_peak, ≈ proportional to mains).
- Load-reg sweep 10 → 100 mA: V_raw drops by ~28 V (reservoir sag plus choke DCR).
Transformer regulation, choke DCR variance, cap ESR drift and ambient temperature each take a few percent. If your V_raw is 448 V at 50 mA instead of 440 V, that's within noise. If it's 400 V or 490 V, something's different — check your real transformer Vrms, choke L at your operating current, and the rectifier drop under load.
Schematic, PCB and photos of the actual bench are pending the v2 ship — this page locks the spec so reproductions can begin in parallel.
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