The Amp Handbook

RigShed gives you four ways to get an amp sound: one of the eight amps built into the app, two of them at once, a capture of a real amp that somebody measured, and your own cabinet impulse response on top of any of those. This explains what each one is actually doing, so you can tell which knob is going to fix the problem you’ve got.

Eight amps · two at once · a mic in front of the cab · NAM captures · cab IRs · all of it free

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The eight amps

Every one of them is a circuit model — not a recording, not a capture. Each is built from the same stages a real amp has, in the same order, and each was fitted numerically against a measured reference rather than dialled in by ear.

Clean	A valve combo into a 12-inch open-back cab. Sparkling clean, breaking up as you dig in.
Ember	A small, early American combo that breaks up the moment you lean on it. Raw, warm and loose.
Chapel	A chiming British combo: bright, glassy cleans that turn to a jangly, vocal crunch.
Brickwork	A big British head with no master volume, crunching from the power valves.
Anvil	A British head with an extra gain stage: hot, forward and aggressive.
Satin	A smooth, compressed boutique overdrive that sings. Fluid leads, touch-sensitive rhythm.
Furnace	Modern American high gain: tight, scooped and huge, for low tunings.
Foundry	Cascaded high gain into a closed-back 4x12. Tight, heavy and still alive to the hand.

The order of the circuit is the point

Signal goes in, through the coupling stages and one to four preamp stages, into the tone stack, through the master into the power amp, and out through the speaker. The tone stack sits before the power stage, and presence and depth sit after it as negative feedback — because that is where they sit on the circuit.

What changes from one amp to the next is how many preamp stages there are, which parts the tone stack uses, how hard the power section is driven and what speaker it drives. Everything else is a filter corner or a gain, fitted against the measurement.

Which means the bass knob is a gain control

Turn the bass up and you are not just adding low end — you are pushing more signal into the valve stage, so the amp distorts earlier and harder. That is how the real circuit behaves and it is why a bass-heavy setting sounds thicker and dirtier rather than just boomier.

If you want more low end without more breakup, pull the drive back as you turn the bass up.

Noon is the amp

Every tone control is centred. With bass, mid, treble and presence all at noon, you are hearing that amp exactly as it was modelled — the controls move either side of that rather than building a sound up from flat.

Drive at noon is the sound of the amp it was measured against. That is not a coincidence or a convention: each of the eight was fitted so that the middle of its gain knob lands on the reference. It is why the factory rigs keep the gain near noon and find their character in the pedals and the tone stack, rather than by pushing an amp somewhere it was never fitted.

Below noon backs the valve stages off toward clean; above pushes them into breakup.

So if you have twisted everything and lost the plot, put the four tone controls and drive back to noon. That’s not a neutral setting, it’s the setting, and it’s a better starting point than anything flat.

Two things you’ll feel before you hear

Sag. Under sustained load the supply droops, so a hard-strummed chord compresses instead of just getting louder. It’s why the amp pushes back when you dig in, and why strumming harder past a certain point changes the texture rather than the volume.

Presence sits before the distortion. Hard playing drives the top end into compression harder than the mids, so the brightness backs off as you play harder and comes back as you ease up. That level-dependent loss of brightness is most of what separates a valve amp from an EQ curve, and it’s the reason the amp feels responsive to your right hand rather than just loud.

Neither has a control. They’re in the model.

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Two amps at once

Both amps sit at the amp’s place in the chain, so everything after the amp is after both of them. There is one set of pedals, one EQ, one delay — they just have two amps in front of them instead of one.

In series, the first amp drives the second. This is the pedal-platform trick done properly: a clean amp pushed hard into a dirty one behaves differently from either amp alone, because the second one is being fed something already compressed and already shaped.

In parallel, the same guitar goes to both and a blend sets how much of each you hear. This is how you get a sound that is genuinely two amps rather than one amp with more gain — a tight high-gain amp for the attack and a looser one underneath it for the body, mixed to taste.

The second amp is a full amp, not a copy of the first. Any of the eight, or a capture of its own, with its own cab and its own microphone. A rig remembers the second amp exactly the way it remembers the first.

Which one to reach for

Series when you want one sound that could not come from one amp. Parallel when you want two sounds at once and the blend between them is the point.

If a parallel blend sounds worse than either amp on its own, that is usually phase: two different cabs arriving at slightly different times. Try the same cab on both, or move one microphone’s distance, before you decide the idea does not work.

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The microphone in front of the cab

A speaker on its own is only half of a recorded amp. The other half is where the microphone is standing, and that is a bigger change than most tone controls.

Type	Dynamic, condenser or ribbon — or As voiced, which is how the cab was measured
Position	Across the speaker, from the centre of the cone out to the edge
Distance	Up against the grille, or backed off it

Centre of the cone is bright and direct and can be harsh; out towards the edge is darker and rounder. Close is tight with more low end; further back picks up more of the room and loses the thump.

Set independently for each amp, so two amps in parallel can be miked two different ways — which is often the fix when a blend is not working.

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Loading a capture

A capture is a profile of a real amp that somebody measured and shared as a .nam file. Thousands are freely available online. Load one and RigShed plays your guitar through it.

Open the capture browser and pick a file. Loading takes a moment — the model has to be read and prepared — and then the amp panel changes.

Why the knobs disappear

When a capture loads, the amp panel shows that amp’s face and two controls only: Level and Mix. This surprises people, so it’s worth being plain about why.

A capture is a snapshot of one amp with its knobs in one position. Whoever made it chose those settings before they measured it. There is no bass control inside the file to expose — the tone stack was set, and then the whole thing was captured as a single behaviour. Giving you a bass knob would mean bolting an EQ onto the outside and pretending it was the amp’s own, which is exactly the sort of thing this app doesn’t do.

So a capture gives you what it is:

Control	What it does
Level	How loud the captured amp comes out
Mix	Blends the captured sound against your dry signal. Leave it up unless you’re deliberately parallel-blending

If you want a different tone from a capture, the honest routes are a different capture, or the pedals in front of it — which is what you’d do with the real amp too.

Getting your tone back

The eight amps are still there. Unload the capture and the full set of controls comes back. Nothing is lost by trying one.

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Cab impulse responses

An impulse response is a measurement of a speaker cabinet in a room. Load a .wav IR and it becomes the cabinet your amp plays through.

The IR replaces the speaker — it doesn’t stack on it

This is the one thing to understand. When you load a cab IR, RigShed switches its own speaker off and feeds the IR a raw power-amp signal instead.

Most software gets this wrong and leaves both in the chain, which puts two cone roll-offs and two resonances in series. The result is boxy, muffled, and no amount of EQ properly fixes it. You get the cab you chose, not two cabs.

Presence stays on either way, because presence is power-amp feedback rather than part of the speaker. That’s the correct place for it.

One consequence worth knowing

If you load an IR and the sound goes thin and fizzy, that’s not a fault — it’s what a power-amp feed sounds like through a cab that isn’t doing much. Try a different IR before you start reaching for EQ. IRs vary enormously in quality, and a bad one sounds bad through anything.

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Working order

The three parts stack in a fixed order, so set them in that order:

1. Pick your amp — one of the eight, or a capture. This is the biggest decision and everything after it is a refinement.
2. Pick your cabinet — the amp’s own speaker, or your IR. This changes the sound more than any tone control will.
3. Place the microphone. Type, then position, then distance. Still a bigger change than the tone controls, so it comes before them.
4. Then the tone controls, if you’re on one of the eight. Adjusting EQ before you’ve settled the cabinet and the mic means doing it twice.
5. Then the pedals, which sit in front and drive the amp.

Adding a second amp comes after all of that, not during it. Get one amp right first, or you will be chasing two sets of controls at once and will not know which one caused what.

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What the free tier holds

	Free	Pro and Stage
Amp captures stored	Unlimited	Unlimited
Cab IRs stored	Unlimited	Unlimited
Saved rigs	3	Unlimited

Every amp, every cabinet, the microphone in front of it and every tone control are free and stay free — and so are as many captures and impulse responses as you care to load. There is no cap on your own files on any tier. The only limit here is how many finished rigs you keep.

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If something seems wrong

Symptom	Cause
Capture sounds quiet or thin next to one of the eight	Captures are made at whatever level the maker chose. Use Level to match, and check Mix is fully up
Only two knobs on the amp	A capture is loaded. That’s all a capture has — unload it for the full set
Mic position does nothing	A capture that includes the speaker has its own mic baked in. The control applies to our cabs and to your IRs
Loaded an IR and it went boxy	Unlikely to be stacking, since the speaker switches off automatically. More often the IR itself, or an IR of a cab you don’t actually want
Amp distorts as soon as I turn the bass up	Working as designed — the tone stack drives the valve stage. Back the drive off
Playing harder gets darker, not louder	Also working as designed. That’s presence sitting before the distortion, plus sag
Parallel blend sounds worse than either amp	Usually phase — two cabs arriving at slightly different times. Try the same cab on both, or move one mic’s distance
Second amp is inaudible	In series it feeds the first; check the blend only applies in parallel. In parallel, check its Level
Brief pause when loading a capture	The model is being read and prepared. It happens once per load, not while you play