Tube Roller — User Guide

This is the practical how-to guide for using Tubeofile's rolling feature. If you're looking for background concepts (what "target" means, why Pa_max matters, what "triode-strapped" does), see the Tube Rolling FAQ. This guide assumes you already understand the basics and want to know how to use the tool effectively.

Safety first. On your first visit to a rolling report you'll see a short safety disclaimer. Please read it. Rolling reports are a data-driven starting point, not a guarantee that a substitution is safe for your specific amplifier. For signed-in users the acceptance is remembered across sessions; anonymous users see it once per browser session.

What the rolling tool does

For any tube in the database, Tubeofile can answer the question: "What else could I put in this socket?" It compares every other tube in the database against the target across heater voltage, socket base, pinout, and behavioral specs (mu, gm, ra, Ia, Pa_max, Vs, Cgp), then ranks candidates by how close a match they are. It also knows about pin-remapping adapters, so it can suggest tubes that fit a different socket but can work via a simple adapter.

The output is a rolling report — a single page that shows you every viable substitute at a glance, filtered down to just the ones that make sense for your amp.

Opening a rolling report

Navigate to any tube's detail page (e.g. /tubes/EL34). If a rolling report is available for that tube, you'll see a ⚡ Roll button in the action row near the top, next to the Collection / Wishlist / Compare buttons. Click it.

Not every tube has a rolling report yet. Reports are pre-generated for the most common tubes and gradually expanded. If you don't see the Roll button on a tube you care about, check back later or request it.

Report layout

A rolling report is divided into sections, from the immediate answer at the top to deeper reference material at the bottom:

1. Jump-to navigation bar — sticky at the top of the page, lets you jump between sections without scrolling
2. Drop-in Replacements — same tube, different manufacturer designations (no analysis needed)
3. Best Picks — the closest-matching candidates, across all modes
4. Target — {mode} — the reference specs for the tube your amp was designed for
5. Rolling Candidates — {mode} — the full candidate table for that mode
6. Adapters — pin-remapping adapters referenced by any candidate in the tables above

For pentodes with triode-strapped data, the Target and Candidates sections repeat once per mode (Pentode Mode, then Triode-Strapped Mode), interleaved so each target card sits directly above its candidate table.

Drop-In Replacements

The first section lists tubes that are the same tube sold under different names — military designations (VT-229), European alternates (ECC35), Soviet alternates (6P14P), etc. These are electrically identical and always safe. No analysis needed; they're the first thing to look for if you just want a spare.

Best Picks

A handful of "close" candidates surfaced at the top so you don't have to read the full table. Two things to notice:

• The counts bar shows: total candidates, how many scored as close, how many are drop-in (no adapter needed), and how many need an adapter
• Each best pick card shows the tube name, drop-in vs adapter, its heater voltage, and its status badge. If you're signed in and own the tube, a small ● owned chip appears next to its name

If Best Picks has enough options for you, you might not need to read the full table at all.

Target card

Directly above each candidate table is the target card — specs for the tube your amp was designed for. This is the reference everything else is compared against. The target card shows:

• Base (e.g. Octal, Noval) — the socket type
• Heater (e.g. 6.3V / 1.5A) — voltage and current your amp's heater supply needs to deliver
• Type (e.g. power pentode, small-signal triode)
• DHT badge if the target is a directly heated triode (important — DHTs and IHTs aren't interchangeable)
• Electrical specs (mu, gm, ra, Ia, Pa_max, etc. — only shown if the target has that parameter for the mode)
• Pinout — each pin labeled by function

Everything in the candidate table below compares against this card.

Candidate table — reading a row

This is the heart of the report. Each row is one candidate tube being evaluated against the target. Here's what the columns mean:

Tube

The candidate's type number. Click it to jump to that tube's own detail page. If you own it, an ● owned badge appears next to the name.

Status

One of four labels, with a color:

• ✓ Close (emerald) — all behavioral parameters within threshold AND Pa_max ≥ target. Best match.
• ✓ Safe (cyan) — Pa_max ≥ target but some parameters are outside threshold. Safe but different character.
• ⚠ Close, low Pa (amber) — parameters within threshold but Pa_max < target. Safe in lightly-loaded circuits.
• ⚠ Low Pa (amber) — Pa below target AND parameters outside threshold. Experimental.

Full definitions in the status FAQ.

Spec columns (mu, gm, ra, Ia, Vs, Cgp)

Each cell shows the candidate's value for that parameter, plus a percentage diff from target:

11,000  -35%
   ▬▬|

• No percentage means the values match exactly
• Gray percentage means the difference is within threshold (similar behavior)
• Amber percentage means the difference exceeds threshold (noticeable deviation)
• The little bar underneath is a visual magnitude indicator — centered at zero, extends left for negative, right for positive. Amber when outside threshold, cyan-tinted when within. It's purely for eye-scanning the column quickly

Spec columns are hidden in compact mode.

Pa

Max plate dissipation (watts). Same format as other spec columns — value plus percentage diff. Pa is a hard safety limit: a candidate with Pa well below the target cannot safely replace it in a heavily-loaded circuit.

Ah

Heater current in amps. Matters because your amp's heater supply has to deliver enough current. A candidate with significantly higher Ah than target may overload the supply.

Fit

• drop-in (emerald) — same socket base and same pin assignment as target. No adapter needed
• Adapter label (gray, with tooltip) — needs a pin-remapping adapter. Hover for the full adapter ID. Scroll to the Adapters section at the bottom for the pinout diagram

Filters and controls

The filter bar at the top of each candidate table is sticky — it stays visible while you scroll the table so you can toggle filters without scrolling back up. It has four rows:

Heater voltage chips

One chip per heater voltage present in the candidate set, with a count next to each. The chip matching your target's heater voltage is highlighted in emerald and marked with a ●.

By default, only the target heater voltage is selected. This is because the most common rolling case is "what can I put in my amp without changing the heater supply?" — and tubes with a different heater voltage need a supply modification.

Click any chip to toggle it. Use the show all link to enable all voltages at once, or target only to reset to the default.

If no candidates match your filters because you excluded the target Vh, an inline "Show candidates on other heater voltages" button appears in the empty state.

Fit chips

Three options: Drop-in only (default), Adapter only, or All. The "Fit" of a candidate is whether it plugs into the target's socket directly or requires a physical pin-remapping adapter:

• Drop-in only is the default because it represents the friction-free case — no hardware to buy or build, just pull one tube out and plug the other in
• Adapter only is useful if you already have (or can source) adapters and want to see only the tubes that would use them
• All combines both

Within any sort order, drop-in candidates always appear before adapter candidates as a visual tiebreaker, so even in "All" mode you'll see the zero-friction options at the top.

Status chips

Same toggle pattern. By default all four statuses are selected. Click any to hide candidates with that status. Common workflow: click "Low Pa" and "Close, low Pa" off to hide anything with lower power rating than target.

View controls (right side)

• ▦ Compact — toggles compact mode. Hides spec columns for a denser list. Useful when you just want to see names + status + power rating. Compact mode is ON by default — click to switch to the full view with all spec columns
• ⚙ Thresholds — opens the threshold slider panel (see next section). A * on the button means you have custom thresholds set

Threshold sliders (power users)

Click ⚙ Thresholds to reveal a collapsible panel with a range slider per behavioral parameter. Each slider controls the ±% tolerance for amber highlighting:

• If a candidate's gm differs from target by more than the gm slider value, the cell is highlighted amber
• Move the slider left to tighten tolerance (more amber highlighting, harsher grading)
• Move the slider right to loosen tolerance (less amber, more forgiving)
• Click the ↺ next to a slider to reset it to the report's default
• Click reset all to reset every slider

Important scope limit: threshold sliders only change the visual amber highlighting. They do not change candidate status labels. The close / safe / low Pa classifications come pre-computed from the report JSON using the report's original thresholds.

The sliders are for power users who want to visualize their own tolerance. They're not URL-persisted.

Compare selected

The target tube is always pre-selected — a floating pill at the bottom of the screen shows target + 0 selected when you arrive. The point of rolling is comparing candidates against the target, so the target is pinned and can't be unchecked.

Tick the checkbox on any candidate row to add it to the comparison set. Up to three additional candidates can be selected (compare page limit is 4 total). Selected rows get a subtle cyan highlight.

The floating pill always shows:

• target + N selected where N is the number of additional candidates
• A clear button that resets to just the target
• A Compare → action that activates once you have at least one candidate selected (giving target + candidate = 2 tubes minimum for a meaningful comparison)

Clicking Compare → takes you to the Compare page with all selected tubes pre-loaded side-by-side.

Use it when you want to dig into the spec differences between a handful of top contenders that all look promising in the table.

Data quality badge

Each tube in the database is tagged with a data quality tier — high, medium, or low — shown as a small colored badge next to the manufacturer name on the tube detail page. This reflects how completely the tube's core specs have been filled in:

• ● High (emerald) — base, heater, all universal parameters, and ≥50% of desirable parameters present. Safe to use for design decisions
• ● Medium (cyan) — at least 60% of universal parameters and pins present, but some key data is missing. Verify critical values against datasheets
• ● Low (amber) — significant gaps in core data (missing base, heater, universal parameters, or pins). Treat as a research stub; always cross-reference with datasheets

Hover the badge for the full explanation. The tier is computed by the import pipeline's scoring rules — not a subjective rating — so if you spot a tube flagged "low" that you have good data for, please report it so we can improve the record.

Collection overlap (signed-in users)

If you're signed in and have tubes in your collection, candidates you already own get an emerald ● owned badge next to their type number in both the Best Picks cards and the candidate tables.

Use it for the common workflow: "I want to roll my amp tonight. What's already on my shelf that will work?" Scan for owned tubes with a close or safe status.

Sharing reports with filters applied

The filter state is persisted in the URL query string. That means any combination of filters you set produces a unique, shareable link:

• ?status=close — only close candidates
• ?vh=all — show all heater voltages
• ?vh=6.3,12.6 — only these two heater voltages
• ?fit=all — show both drop-in and adapter candidates (default is drop-in only)
• ?fit=adapter — only adapter candidates
• ?sort=Pa_max:desc — sorted by Pa descending
• ?compact=0 — full view (default is compact)

Multi-mode reports (pentodes with triode-strapped data) prefix the params per mode:

• ?p_status=close — pentode mode filtered to close
• ?t_status=safe,low_pa&t_vh=all&t_fit=all — triode-strapped filtered independently
• The compact flag is global across modes since it's a display-only preference

Just copy the URL from your browser's address bar once you have the view you want. Sending it to someone else (or bookmarking it) will reproduce the same filter state.

Adapters section

Every candidate whose Fit column says anything other than "drop-in" references an adapter by ID. The Adapters section at the bottom lists every referenced adapter with:

• Name + ID — the shorthand notation like Noval>Octal:g1khha (see adapter IDs FAQ)
• Availability — rough indicator: Common / Uncommon / Rare / Same base rewire
• Pinout diagram — the pin mapping the adapter performs
• Tube list — all candidates in the report that use this adapter

The adapters section is auto-collapsed when there are more than four adapters (to keep the page short). Click ▸ show to expand it.

Recipes — common workflows

"I want to roll my amp tonight with zero modifications"

1. Leave heater, fit, and compact at their defaults (target Vh, drop-in only, compact view)
2. Turn off "Safe", "Close, low Pa", and "Low Pa" in the status filter — keep only "Close"
3. Everything remaining is a zero-friction substitution that should work without adapters or rebiasing
4. If you're signed in, look for ● owned badges first — those need zero shopping

"I want a different sound but still safe"

1. Keep heater and fit at their defaults (target Vh only, drop-in only)
2. Keep only "Close" and "Safe" in the status filter
3. Tick a few promising candidates — the target is already pre-selected
4. Click Compare → in the floating pill to see target vs candidates side-by-side

"I want to experiment — show me everything"

1. Click All in the Fit filter to include adapter-based candidates
2. Click show all next to the heater chips
3. Keep all four statuses selected
4. Toggle off Compact mode to see the full spec columns
5. Sort by Pa ascending to find the lowest-power options (most character change)
6. Be ready to buy adapters and/or modify your amp's heater supply

"I already own tubes — what can I use?"

1. Sign in
2. Default filters are fine
3. Scan the candidate tables for ● owned badges
4. If there are many, use Compact mode to see the list at a glance

"What's the closest 2A3 substitute I could actually build with an adapter?"

1. Open /tubes/2A3/roll
2. Sort by Status ascending so close rows come first
3. Look at the Fit column — candidates labeled "need_adapter" use one of the adapters listed at the bottom
4. Hover the adapter label for the ID, then scroll to the Adapters section for the pinout

Safety disclaimer

The rolling report is a data-driven starting point, not a guarantee. Always:

• Understand your amplifier's bias scheme (fixed vs cathode) before hot-swapping tubes
• Check headroom on Pa — a tube rated 25W in a circuit pushing 23W has no margin
• Verify the adapter correctly maps all pins for your specific tube
• Trust the datasheet, not the computer — if something looks off in the report, cross-reference the source

More detail in Are rolling recommendations safe to follow blindly? in the FAQ.

Further reading

• Tube Rolling FAQ — background concepts, not how-to
• API documentation — if you want to consume rolling data programmatically