Quick Reference
The values, codes, and conventions used throughout the site, pulled into one page for fast lookup. Each table links back to the chapter that explains the why behind the numbers.
Unit Prefixes
Capacitors climb pF → nF → µF; resistors climb Ω → kΩ → MΩ. Each step is ×1,000.
| Prefix | Multiplier | Used for |
|---|---|---|
| p (pico) | ×10⁻¹² | Capacitors (pF) |
| n (nano) | ×10⁻⁹ | Capacitors (nF) |
| µ (micro) | ×10⁻⁶ | Capacitors (µF) |
| — (base) | ×1 | Ohms (Ω), Farads |
| k (kilo) | ×1,000 | Resistors (kΩ) |
| M (mega) | ×1,000,000 | Resistors (MΩ) |
Full chapter: Ohm's Law and Basic Circuit Theory →
Resistor Color Code
Standard 4-band code, read left to right: 1st digit, 2nd digit, multiplier, tolerance.
| Color | Digit | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | ×1 | — |
| Brown | 1 | ×10 | ±1% |
| Red | 2 | ×100 | ±2% |
| Orange | 3 | ×1,000 | — |
| Yellow | 4 | ×10,000 | — |
| Green | 5 | ×100,000 | ±0.5% |
| Blue | 6 | ×1,000,000 | ±0.25% |
| Violet | 7 | ×10,000,000 | ±0.1% |
| Grey | 8 | ×100,000,000 | — |
| White | 9 | ×1,000,000,000 | — |
| Gold | — | ×0.1 | ±5% |
| Silver | — | ×0.01 | ±10% |
| No band | — | — | ±20% |
Example: brown-black-red reads 1, 0, ×100 → 1,000Ω (1kΩ).
Full chapter: Resistors and Capacitors →
Standard Resistor Value Series
Manufactured resistors only come in specific "standard" values within each decade (10-100, 100-1000, and so on) — the tighter the tolerance, the more values are available.
| Series | Tolerance | Values per decade |
|---|---|---|
| E12 | ±10% | 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82 |
| E24 | ±5% | E12 values plus 11, 13, 16, 20, 24, 30, 36, 43, 51, 62, 75, 91 |
| E96 | ±1% | 96 values per decade — used where precision matters (active filters, precision gain stages) |
Multiply any listed value by 0.1, 1, 10, 100, 1k, 10k, 100k, or 1M to reach every value that series offers.
Capacitor Numeric Code
Small ceramic and film capacitors are often printed with a 3-digit code instead of a written value: the first two digits are significant figures, the third is a power-of-ten multiplier in picofarads.
| Code | Value | Code | Value |
|---|---|---|---|
| 101 | 100 pF | 333 | 33 nF |
| 221 | 220 pF | 334 | 330 nF |
| 471 | 470 pF | 474 | 470 nF |
| 102 | 1 nF | 105 | 1 µF |
| 103 | 10 nF | 106 | 10 µF |
| 223 | 22 nF | 475 | 4.7 µF |
Tolerance letter alongside the code: J = ±5%, K = ±10%, M = ±20%.
Capacitor Types
| Type | Typical range | Where you'll find it |
|---|---|---|
| Ceramic | picofarads to low nanofarads | High-frequency filtering, tone-shaping networks |
| Film (polyester/mylar) | nanofarads to low microfarads | Signal coupling, tone stages |
| Electrolytic | microfarads to hundreds of microfarads | Power supply filtering, larger coupling caps — polarized |
| Tantalum | microfarads range | Compact power filtering — also polarized |
Full chapter: Resistors and Capacitors →
Reference Designators
| Prefix | Component |
|---|---|
| R | Resistor |
| C | Capacitor |
| Q | Transistor |
| D | Diode |
| U / IC | Integrated circuit, including op-amps |
| VR / P | Potentiometer |
Full chapter: Reading Schematics →
Bipolar Transistor Types
| Type | Symbol tell | Common pedal role |
|---|---|---|
| NPN | Arrow on emitter points outward | Most modern pedal designs — 2N3904, 2N5088 |
| PNP | Arrow on emitter points inward | Classic fuzz circuits, germanium-era designs — AC128, 2N2907 |
| Silicon | — | Predictable, temperature-stable, higher gain |
| Germanium | — | Lower turn-on voltage, softer clipping, temperature-sensitive |
Full chapter: Transistors and Diodes →
Common Op-Amp Chips
| Chip | Common pedal association |
|---|---|
| 741 | Early, simple designs — historically significant, now mostly superseded |
| 4558 / RC4558 | Tube Screamer and Tube Screamer-derived overdrives |
| TL072 / TL082 | Widely used general-purpose pedal op-amp — low noise, JFET input |
Potentiometer Taper Markings
| Marking | Taper | Typical use |
|---|---|---|
| A | Audio (logarithmic) | Volume, gain controls |
| B | Linear | Blend/mix controls, some tone and rate controls |
Full chapter: Potentiometers →
LED Resistor Values
R = (Supply Voltage − LED Forward Voltage) ÷ Desired Current.
| Supply | Typical red LED Vf | Target current | Resistor (rounded up) |
|---|---|---|---|
| 9V | ~2.0V | 10mA | 1kΩ |
| 9V | ~2.0V | 5mA | 1.5kΩ |
| 18V | ~2.0V | 10mA | 1.6kΩ |
Full chapter: LED Indicator Wiring →
Power Jack Convention
Nearly every pedal uses a 2.1mm barrel jack, center-negative — the inner pin is negative, the outer sleeve is positive. This is backwards from a lot of consumer electronics, so a generic "9V" wall adapter isn't safe to assume. Check the polarity diagram printed on the supply before plugging in anything unfamiliar.
Full chapter: Power Supply Conventions and Polarity Safety →
Jack Contacts
| Jack type | Contacts | Typical use |
|---|---|---|
| Mono (TS) | Tip (signal), Sleeve (ground) | Output jack |
| Stereo (TRS) | Tip (signal), Ring, Sleeve (ground) | Input jack — ring wired for the battery-cutoff trick |
Component Substitutions
What to reach for when a specified part is out of stock — not every substitute is a drop-in, so check the note before swapping.
| Application | Primary | Substitutes | Note |
|---|---|---|---|
| Small-signal NPN | 2N3904 | BC547, BC549 (low-noise) | Check pinout — packages differ |
| Small-signal PNP | 2N3906 | BC557 | — |
| JFET buffer | J201 | 2N5457, MPF102 | I_DSS varies — may need a bias resistor tweak |
| Signal/clipping diode | 1N4148 | 1N914, 1N4454 | Electrically identical |
| Germanium clipping diode | 1N34A | OA91, OA95 | Verify Vf ≈ 0.3V before use |
| Rectifier, 1A | 1N4007 | 1N4004, 1N4005 | Always use 1N4007 (1000V rating) in tube amps |
| Overdrive op-amp | JRC4558D | RC4558, NJM4558 | Swap measurably changes character, not just a brand change |
| Buffer/preamp op-amp | TL072 | TL082, TL062 (lower power) | Higher input impedance than 4558-family parts |
| Preamp tube (high gain) | 12AX7 (ECC83) | ECC803S | Pin-compatible; premium version has tighter tolerances |
| Preamp tube (lower gain) | 12AT7 (ECC81) | 5751 | 5751 runs roughly 70% of 12AX7 gain |
| Output tube (6L6 family) | 6L6GC | 5881, KT66 | Not fully interchangeable — re-check bias and socket wiring |
| Output tube (EL34 family) | EL34 | 6CA7, KT77 | Rebias required after any swap |
General rule: re-check bias after any output tube substitution — see Tube Amp Fundamentals and Common Amp Mods.
3PDT Footswitch Pole Functions
| Lug row | Typical pedal function |
|---|---|
| Pole 1 (signal in) | Routes input signal to either the circuit or straight to output |
| Pole 2 (signal out) | Routes the circuit's output (or bypassed input) to the output jack |
| Pole 3 (LED) | Switches the status LED's ground connection (or supply) |
Full chapter: Footswitch and True-Bypass Wiring →
Pot Value and Tone Cap Guide by Pickup Type
A starting point, not a rule — see why pot value and pickup loading interact before assuming these are fixed.
| Pickup type | Volume pot | Tone cap |
|---|---|---|
| Single-coil (Strat/Tele) | 250kΩ, audio taper | 47nF |
| Humbucker (Les Paul style) | 500kΩ, audio taper | 22nF |
| P-90 | 500kΩ, audio taper | 47nF or 22nF |
| Jaguar / Jazzmaster | 1MΩ, audio taper | 47nF |
Full chapter: Pots, Caps, and Tone Controls →
Treble Bleed Starting Values
| Pickup / pot | Capacitor + resistor (series) |
|---|---|
| Single-coil, 250kΩ pot | 470pF + 220kΩ |
| Humbucker, 500kΩ pot | 470pF + 150kΩ |
| Jaguar/Jazzmaster, 1MΩ pot | 1000pF + 100kΩ |
Full chapter: Pots, Caps, and Tone Controls →
4-Conductor Humbucker Wire Colors (Seymour Duncan / DiMarzio)
This specific color code is shared by these two manufacturers — it is not universal. Always check the manufacturer's own chart before wiring an unfamiliar pickup.
| Color | Function |
|---|---|
| Red | Coil 1 hot (series link) |
| White | Coil 1 ground (split tap) |
| Green | Coil 2 ground (series link) |
| Black | Coil 2 hot (output) |
| Bare | Ground shield |
Full chapter: Switching Systems →
Common Wiring Configurations
| Config | Signal path |
|---|---|
| SS (Telecaster) | Neck/bridge → 3-way switch → volume pot (250kΩ) → tone (47nF) → jack |
| HH (Les Paul) | Each humbucker → its own volume (500kΩ) and tone (22nF) → 3-way toggle common → jack |
| HSS (Strat) | Bridge HB + 2 singles → 5-way switch → shared volume (500kΩ) → shared tone (47nF) → jack; middle pickup is RWRP |
| HHH independent (swimming pool) | Each humbucker → its own SPST on/off → shared node → master volume/tone → jack |
| Active (EMG-style) | Pickup → preamp (1MΩ input) → low-value volume pot (25kΩ) → jack; battery powered via switched TRS ring |
Full chapter: Wiring Diagrams and Signal Flow →
Common Tube Types
| Tube | Type | Typical use |
|---|---|---|
| 12AX7 (ECC83) | Dual triode, high gain | Preamp gain stages — the default in most guitar amps |
| 12AT7 / 12AU7 | Dual triode, lower gain | Phase inverter, reverb driver |
| EL84 (6BQ5) | Pentode | Output, 10-15W class amps |
| 6V6GT | Beam tetrode | Output, 10-22W class amps |
| 6L6GC / EL34 | Beam tetrode / pentode | Output, 25-100W class amps |
| 5Y3GT / GZ34 (5AR4) | Rectifier | Converts mains AC to B+ DC — GZ34 sags less than 5Y3 |
Full chapter: Tube Amp Fundamentals →
A note on buying tubes: remarked and mislabeled tubes — a common part relabeled as a rarer, more valuable one — are a documented problem in the secondhand/NOS tube market broadly, reported from sellers in multiple countries, not any one region specifically. Buy new-production and NOS tubes from a supplier with real return policies and a track record (see Where to Buy Guitar, Pedal, and Amp Parts) rather than the cheapest unverified listing, especially for anything sold as vintage or NOS.
Speaker Impedance Combinations
| Speakers | Parallel | Series |
|---|---|---|
| Two 8Ω | 4Ω | 16Ω |
| Two 16Ω | 8Ω | 32Ω |
| Four 16Ω (series-parallel: two pairs in series, paralleled) | 16Ω total | |
Matching amp output impedance to cabinet impedance matters in one direction more than the other: a cabinet with lower impedance than the amp expects can draw more current than the output transformer is rated for — a real damage risk. A cabinet with higher impedance is safe, just quieter.
Full chapter: Speakers and Cabinets →
Classic Circuit Key Values
| Circuit | Key values |
|---|---|
| Stratocaster (3-pickup, 5-way) | 250kΩ pots, 47nF tone caps, middle pickup RWRP |
| Les Paul (2-humbucker, 3-way toggle) | 500kΩ pots, 22nF tone caps, independent volume per pickup |
| Telecaster (2-pickup, 3-way) | 250kΩ pots, 47nF tone cap |
| Jaguar/Jazzmaster (offset, floating bridge) | 1MΩ pots, 47nF tone caps, independent on/off per pickup |
| Tube Screamer (TS808/TS9) | JRC4558D op-amp, 1N4148 clipping diodes, ~510kΩ feedback resistor |
| Distortion+ | TL071 op-amp, 1N4148 diodes to ground, ~1MΩ feedback resistor |
| Fuzz Face | Two PNP transistors (germanium AC128 or silicon 2N3906), ~33kΩ feedback |
| Big Muff Pi | Four BJTs, four 1N4148 diodes, cascaded hard clipping, passive tone control |
| Deluxe Reverb (AB763) | 12AX7 preamp, 6V6 output, GZ34 rectifier, ~22W |
| Marshall Plexi (1959 Super Lead) | 12AX7 preamp (4 stages), EL34 output, solid-state rectifier, 100W |
| Vox AC30 (Top Boost) | 12AX7 + EF86 preamp, 4× EL84 output, GZ34 rectifier, Class A, 30W |
| Rangemaster treble booster | Single OC44 germanium transistor, positive ground, ~5nF input cap |