Methodology

Primary sources

Amperatubes does not republish datasheets. Specifications come from the original manufacturer documentation, and every numeric value in the catalog is cross-checked against at least two of the following references:

• RCA Receiving Tube Manual (RC-15 through RC-30), for type characteristics, ratings and application notes.
• Mullard Application Reports & Master Catalogue, for European ECC / EL / EF series.
• Tung-Sol & Sylvania Engineering Bulletins, for beam-power and rectifier types.
• Philips ECG Tube Catalog, for cross-references and equivalents (military, RETMA, ETA).
• Frank Philipse's Tube Data Sheets (frank.pocnet.net), for digitised primary documents.
• Western Electric Engineering Letters, for the 300B / 274B / 421A and related transmitting types.

When a spec varies between sources (revision, manufacturing era, or regional rebadge), the catalog favours the most conservative value and flags the disagreement in the data quality report.

SPICE models

The 286 SPICE models in Amperatubes are not synthesised. Each one comes from a published audio-engineering source and is tagged with its origin in the per-tube page:

• Norman Koren — triode and pentode formulations documented in his SPICE tube modelling articles. The Koren v3 model is the default for triodes; v1.3 is preserved where the original parameters exist in the published literature.
• Ayumi Nakabayashi — improved triode model published in 2002, used for tubes where the original Koren fit diverges noticeably from measured curves.
• Derk Reefman, Wayne Kirkwood,Robert Cordell, Adrian Immler — published refinements for specific tubes (mostly output pentodes and rectifiers).

Curves rendered in the loadline calculator are recomputed at runtime from the model parameters — not from a pre-baked image — so a parameter correction propagates everywhere without manual asset updates.

Editorial content

The 47 long-form guides under /learn/ and the deep-dive encyclopaedia sections on flagship tubes (12AX7, 5998 and growing) are written first-hand. Where a technique or measurement comes from an external author, the attribution is in the page itself — there are no anonymous editorial team bylines. Recurring references include:

• Morgan Jones, Valve Amplifiers (5th ed., Newnes 2018).
• Merlin Blencowe, Designing Tube Preamps for Guitar and Bass and Designing High-Fidelity Tube Preamps.
• Jack Darr, Electric Guitar Amplifier Handbook.
• Aiken Amplification (Randall Aiken) technical pages.
• The Valve Wizard (Merlin Blencowe's public site).

Audit pipeline

The catalog is regenerated on every build. A pre-build script cross-references the tube specs against a vendor matrix and emits an audit report covering 8 verification dimensions per tube (manufacturer, era, dissipation, heater, μ, gm, rp, base) plus per-tube datasheet visibility. The current state ships at /about/qualite-donnees/ — 328 of 339 entries are fully verified at time of writing; the remainder are flagged with the specific spec under dispute. Nothing is hidden.

What we don't do

• No LLM-generated tube summaries. Every editorial paragraph is human-written. Auto-generated short summaries (for tubes still pending full coverage) are clearly marked at build time and use a deterministic template, not a language model.
• No affiliate links in the body of editorial pages.Where there is a transparent product mention, it is in a dedicated outbound block, never woven into spec tables.
• No paywall. Every page, every calculator, every SPICE download is free, no signup.
• No tracking beyond aggregate site analytics (Vercel Speed Insights + page-views). No advertising trackers, no behavioural fingerprinting.

Reporting an error

The catalog is wrong somewhere. If you find a spec that disagrees with your primary source, or a SPICE curve that mis-fits your bench measurement, please use the contact form on /about/ and include the source. Corrections are processed within the next build cycle; significant changes get a note in the change log.