Dr. Fill Manual

1 · What's new

New in 0.1.53:

• Drop drum loop. A dashed Drop drum loop key now sits in the top-right corner of the screen. Click it to browse for a loop of your own; it lights up when you drag a file over the window. Getting audio in

Version 0.1.51 was a new face for Dr. Fill — everything it did before, laid out as one instrument panel instead of a scrolling page:

• A new faceplate. One fixed screen with no scrolling: the loop display across the top, a Preview / Tempo section, the fill pads with the Library beside them, and an Export column. The faceplate at a glance
• Resize it to any size. Drag the window's corner and the whole interface scales with it — text, pads, meters — on Mac and Windows. Window size, themes, tour & help
• Output fader and VU meters. A console fader sets how loud previews play, and a stereo pair of analog VU meters shows the level, with a red lamp when the output clips. Output level & fader automation
• Fader automation. Record fader moves over the phrase — or draw them on the waveform — for crescendos and drops. They play back with the fader moving by itself, and print into your WAV and MIDI exports. Output level & fader automation
• Loop display. The starter loops, the Vault library and Open an audio file… are one click on the loop display, with ‹ › to step through the starters. Getting audio in
• Hint bar. Point at any pad and the bar along the bottom tells you what that fill does; it also narrates what Dr. Fill is busy with. The faceplate at a glance
• Vault library, redesigned. It opens as a panel over the pads; click the Dr. Fill logo (or Close) to go straight back. Getting audio in
• Crimson theme. A red-accented theme joins Original, Aurora and Cool Light. Window size, themes, tour & help

2 · What Dr. Fill is

Dr. Fill answers one question: what fill goes here? Give it one bar of your drum loop and it plays that bar back twice — the second time with the tail replaced by a fill. Every fill is cut from your loop's own hits: nothing is synthesized, no other samples are involved, so every fill sounds exactly like your kit, at exactly your tempo.

It builds 90 fills from whatever you feed it, spread across five pages — from played-on-a-kit rudiments and linear runs to producer-style tape stops, stutter edits and chops, to the signature vocabulary of the greats. And when none of them is the one, describe the fill you're hearing in your head and Dr. Fill builds that too. You audition, pick one, and take it home as audio (WAV) or as notes (MIDI).

Dr. Fill runs four ways: as an AU, VST3 or AAX plugin inside your DAW (AAX is for Pro Tools, on both Mac and Windows), as a standalone app, and in the browser inside The Vault. The plugin and the standalone app share the instrument faceplate this manual describes; the browser version has the same fills and engine in a scrolling page layout.

3 · The faceplate at a glance

In the plugin and standalone app, everything is on one screen. From top to bottom:

4 · Requirements

5 · Installation

The same installers are always on Your Plug-Ins in The Vault, and they're always the newest release.

Mac

1. Open the downloaded DrFill.pkg and follow the installer. It's signed and notarized by Apple, so there's nothing to bypass.
2. The installer lets you choose what to install: the AU plug-in (Logic Pro, GarageBand), the VST3 plug-in (Ableton Live, Cubase, FL Studio, Studio One and most others), the AAX plug-in (Pro Tools), and the standalone app. All are selected by default.
3. Enter your Mac password when asked (the plug-ins install machine-wide), then restart your DAW.

Installed locations: /Library/Audio/Plug-Ins/Components (AU), /Library/Audio/Plug-Ins/VST3 (VST3), /Library/Application Support/Avid/Audio/Plug-Ins (AAX), /Applications (app).

Windows

1. Run DrFill-Setup.exe and approve the administrator prompt.
2. The installer places the VST3 and AAX machine-wide and the standalone app under C:\Program Files\Yurt Rock\Dr. Fill, and installs Microsoft's WebView2 runtime if it's missing (a one-time, silent step).
3. On the shortcuts page, Create a desktop shortcut for the standalone app is ticked by default — untick it if you only use Dr. Fill inside a DAW. The standalone is always in the Start menu either way, and the uninstaller removes the shortcut with the app.
4. Restart your DAW.

Installed locations: C:\Program Files\Common Files\VST3 (VST3), C:\Program Files\Common Files\Avid\Audio\Plug-Ins (AAX), C:\Program Files\Yurt Rock\Dr. Fill (app).

6 · Activation & licensing

Dr. Fill installs free and opens in demo mode: load loops, capture from a track, and audition all 90 fills with no time limit. Activating unlocks WAV and MIDI export, downloading, and drag-to-DAW.

Click Demo · Activate in the top-right corner of the plugin, then use either path:

• Sign in with Yurt Rock — for Vault members (the membership includes every Yurt Rock plugin) and for people who bought Dr. Fill: sign in with the email you bought it with, or add your key to your account first (see below). No key to type.
• Enter a serial number — the DRFL-XXXX-XXXX-XXXX-XXXX key from your purchase email. Paste it with the Paste button or ⌘V / Ctrl+V.

How sign-in works

1. Click Sign in with Yurt Rock. Your web browser opens on the Yurt Rock sign-in page, and the button in Dr. Fill changes to Waiting for sign-in….
2. Sign in in the browser. Dr. Fill finishes activating by itself — you don't need to switch back first — and the browser page reports the real result: "Dr. Fill is activated. You can close this window and return to Dr. Fill," or a message telling you to return to Dr. Fill for details if something went wrong.
3. Back in Dr. Fill, the panel closes and the chip shows ✓ Active. If the sign-in didn't work, the panel says why (for example, no membership or purchased license on the account you signed in with).

This works the same in every host, including Pro Tools — which hides plugin windows while your browser is in front. If you close and reopen the plugin window while the browser is still open, Dr. Fill picks up the finished sign-in when you come back. Changed your mind? Click Cancel sign-in under the button. If you leave it too long, it times out; just try again.

Once active, the chip stays green — ✓ Active — and Dr. Fill starts without a connection — it only needs to go online now and then to renew its licence in the background. Activation is per-machine with a generous machine limit. To free this computer's slot, open the panel from the chip and click Deactivate this machine.

Managing your license

In The Vault, open vault.yurtrock.com → Your Plug-Ins → Your Licenses. There you can see your key again (lost-key recovery is just signing in), add a purchased key to your account, see which machines are activated, and free up a machine slot with Deactivate — for example after replacing a computer.

7 · Getting audio in

Dr. Fill opens with a starter loop loaded so there's always something to hear. Click the loop display at the top to pick from ten starter loops from the Yurt Rock roster — each at its own tempo — or use its ‹ › arrows to step through them. The same menu opens the Vault library and Open an audio file…. Three ways to work on your audio:

Capture from the track (plugin)

1. Insert Dr. Fill on the track that carries your drums (or on a bus/master carrying them).
2. Press play in your DAW so the loop is running through the plugin.
3. Click Capture in the top bar. The loop display reads Listening to your track, a live waveform shows what the plugin is hearing, and the button counts the seconds (Stop 3.2s). Let a few bars pass, then click it to stop.
4. Dr. Fill finds the cleanest loop inside the take automatically and builds all 90 fills from it.

Drop a file

Drag any audio file — WAV, AIFF, MP3, FLAC — anywhere onto the window; the Drop drum loop key in the corner of the screen lights up while you're over it. To browse instead, click Drop drum loop, or choose Open an audio file… from the loop display. Full-resolution audio in means full-resolution fills out. Dr. Fill reads the tempo from the filename when it's there (loop_97.wav, 120bpm) and estimates it otherwise — and if it guessed wrong, Src … · fix under the big BPM readout corrects it. The big readout itself sets a play-at tempo instead — the whole phrase time-stretches (see Troubleshooting). In the plugin, loops follow your session tempo automatically — see the Host key in Auditioning.

The Vault Library

Vault in the top bar opens the Yurt Rock catalog as a panel over the pads, without leaving your DAW. Pick a pack, press a loop's play key to audition it for free, and Fill pulls it straight into Dr. Fill. Keeping what you make from it comes with the Vault membership. Close — or the Dr. Fill logo — takes you back to the fills.

8 · The 90 fills

Fills live on five pages, listed down the Library column on the left:

Each fill is a pad, with its own color along the top edge. The badge shows its length: 2♩ fills replace the last two beats of the bar; BAR fills take over the whole bar. The small picture follows the export format — the fill's waveform, drawn from your actual audio, when you're exporting WAV; its notes (hats, snare, kick) when you're exporting MIDI. Point at a pad and the hint bar says what the fill does; a ☆ appears in its corner to save it to My Fills.

9 · Describe a fill

The Describe field sits above the pads. Type the fill you're hearing in your head — "chaotic 60s rock tom roll", "lazy behind-the-beat soul fill", "gospel chops into a crash" — and hit Build.

AI turns your description into a rhythm — never audio — and Dr. Fill renders it from your loop's own slices, exactly like the built-in fills, so it always sounds like your kit at your tempo. A thin progress line runs along the field while the hint bar narrates the two steps: writing the rhythm, then playing it on your loop.

• Every result gets its own color-coded pad in a Described row above the page's fills and stays for the whole session, so you can build several and A/B them.
• You can name a drummer or a song in the description — the result captures the feel (subdivision, accents, timing) rather than copying anything.
• Star a described fill (☆ on its pad) to keep it beyond the session — it lands in My Fills and re-renders on whatever loop you load next, just like a built-in.
• If a description can't be built live, it's forwarded to Yurt Rock as a fill request — the roadmap for new built-in fills.

10 · My Fills — starring & Dice Roll

Two extra pages sit at the bottom of the Library list:

• Dice Roll deals 18 fills at random — six from the Drummer pages, six from the Producer pages, six from Legends. Click it again to re-roll. Instant inspiration when you don't know what you're shopping for.
• My Fills collects everything you've starred: built-in fills under From the roster, described fills under Described. Stars are saved on your machine, so your shortlist is waiting next session. Click a pad's ★ again to remove it.

11 · Auditioning

• Click a pad to load that fill into the phrase — the screen shows your bar, then your bar again with the fill in the tail.
• Double-click a pad to hear just the fill on its own; the pad pulses while it plays.
• The big round play button in Preview, or Space, starts and stops the phrase. Under the button it says or press Space, and Playing while it runs.
• In sync with your DAW: in the plugin, when your session's transport is running, the line under the button reads Synced to DAW — press play (or Space) and the phrase waits, then drops in exactly on your DAW's next bar line, at the session tempo. While it waits, the button shows a clock and At the bar…; press again to cancel. With the transport stopped, play starts instantly as always.
• Switching fills during playback keeps the transport position — click between two pads while the phrase loops to A/B them against the same groove without losing your place.
• If the loaded fill lives on a page you're not viewing, a colored dot in the Library list shows where it is.
• Mute track (plugin): the Mute track key under the play button silences your track's own audio while a Dr. Fill preview sounds, so the phrase isn't doubled by the loop it came from. It's on by default (its light is lit); click it to hear both. The setting is remembered.
• In the plugin, every loop auditions at your song's tempo automatically. The Host key under the BPM readout is lit while the DAW tempo is being followed; the whole phrase — bar, fills, previews and exports — time-stretches to it, so what you hear is what lands in the arrangement. It's octave-smart: a 170 BPM loop in an 85 BPM session stays on the half-time grid instead of being slowed to half speed. Typing your own play-at tempo (or ½× / 2×) takes over manually; click Host to follow the DAW again.

12 · Output level & fader automation

The Output fader and meters

In the Export column, the Output fader sets how loud Dr. Fill's previews play, with its level in the readout beside it. It works like a console fader: the far left is off, 0 dB (marked in gold) is about three-quarters along, and the far right is +6 dB.

• Drag the cap — hold Shift for fine moves. Click the groove to jump there.
• Double-click the fader to return to 0 dB.
• The scroll wheel and arrow keys move it in 0.5 dB steps (Shift: 0.1 dB).

On its own, the fader only changes what you hear: your exports, and your track's own audio, stay at their own level. Its setting is remembered.

Below it, two analog VU meters (L and R) show the preview's level after the fader — the phrase, or a single fill when you double-click a pad. The small red lamp in each meter's corner lights when the needle goes into the red or the output hits full scale (clips).

Recording fader moves

For a crescendo into the fill, a drop before it, or any other move, Dr. Fill can record the fader over the phrase — like automation in your DAW. The keys are in the top corner of the screen:

The curve is drawn as a glowing line over the waveform, and the waveform itself grows and shrinks with it. On playback the fader moves by itself, following the curve; grab it at any time to take over.

There is one curve for the whole phrase, and it stays when you switch fills — so you can audition several fills with the same crescendo. It lasts for the session.

13 · Multi-bar loops

Dr. Fill works on one bar. When you load a longer loop, use the Bar stepper under the tempo readout — step through with ‹ ›, or click the readout (1 / 4) to pick a bar from a menu. Bar one isn't always the interesting one; try the bar with the busiest hats or the hardest backbeat and the fills inherit that energy.

14 · Export settings

The Export column on the right sets what you'll take home. The format settings open as menus when you click them:

The current file name is shown above Save (point at it to see all of it). Your choices are remembered between sessions.

15 · Saving & drag-to-DAW

In the plugin (AU / VST3 / AAX) and standalone app

• Save writes the export silently to your Downloads folder and flashes ✓ Saved. Repeated saves get numbered names rather than overwriting.
• The gold strip along the very bottom of the window is the drag handle. It reads Drag to your DAW with the file's name: grab it and pull straight into your DAW's timeline — the file lands wherever you drop it. Clicking the strip (without dragging) opens a save dialog instead. (Trying to drag the phrase waveform itself inside the plugin just shows a reminder pointing at the strip.)
• Both are part of activation: before you activate, the strip reads Activate Dr. Fill to export, and using either opens the activation panel.

In the desktop app and browser

• ↓ Download saves the file (the desktop app saves silently; the browser shows its normal download).
• ⣿ Drag to DAW next to it drags the export anywhere — DAW timeline, desktop, a sampler pad.

16 · The DAW workflow

Dr. Fill is a fill builder with a transport of its own, so you can shop for fills while your DAW is stopped — and when the DAW is running, play locks to it: the phrase drops in on the session's next downbeat, at the session tempo (see Auditioning). The intended loop, using Ableton Live as the example:

1. Insert Dr. Fill (VST3 or AU) on your drum track.
2. Play the track and Capture a few bars. Stop capture; the fills build.
3. Audition inside the plugin — with the section looping in your DAW, leave Mute track on so your source loop drops out under the preview, and press play (it reads Synced to DAW) to hear each candidate land in context, in time. Shortlist two or three (star them so they're on My Fills).
4. Drag each candidate from the gold strip into the arrangement at the fill point (say, bar 8). The audio is cut from your own loop at your exact tempo, so it sits in time automatically.
5. Want it to build? Record a crescendo on the Output fader over the fill (see fader automation) before you drag — it prints into the export.
6. Play the section in context and keep the winner. For MIDI: switch the export to MIDI, drag it onto a track running your drum sampler, and the fill plays through your own sounds.

Previews while the DAW is idle

Some hosts stop feeding audio to a plugin when nothing is happening — Logic does this to tracks that aren't being monitored while the transport is stopped. So that previews stay audible anyway, the AU and VST3 versions then play them to your computer's default output, at your session's own sample rate and buffer size so nothing your DAW is doing changes, and hand back to the channel as soon as the host is processing again.

Pro Tools (AAX) never does this. Dr. Fill won't open a second connection to your interface inside Pro Tools — previews always go through the plugin's channel. If Pro Tools has suspended the plugin on a silent track (its Dynamic Plug-In Processing feature), previews stay quiet until the track is processing again: press play in Pro Tools, or turn Dynamic Plug-In Processing off in Setup → Playback Engine.

17 · Window size, themes, tour & help

Resize the window by dragging its corner (or the edge of the plugin window, in hosts that allow it). The whole interface scales with the window — text, pads, meters and the gold strip — so a bigger window means a bigger instrument, not just more empty space. This works the same on Mac and Windows.

Two small buttons sit at the right end of the hint bar, beside the version number:

• The gear opens the theme picker: Original (the dark gold default), Aurora, Cool Light and Crimson. The readouts stay dark in every theme, like real hardware. Your choice is remembered.
• ? replays the guided tour. It runs by itself the first time you open Dr. Fill, spotlighting each control in turn — getting audio in, the fill pages, Describe, auditioning, the bar stepper, tempo, export settings and taking it home. Skip closes it; Back / Next step through.

Every tour card also carries two links that open in your web browser:

• manual ↗ — this page.
• questions / comments ↗ — Yurt Rock's plugin feedback page, for questions, bug reports and ideas.

18 · Version & updates

The installed version (for example v0.1.53) is shown small at the right end of the hint bar, in the bottom-right corner of the plugin and standalone app. When a newer release is available, a gold Update available · vX.Y.Z ↗ link appears beside it; click it to open Your Plug-Ins on The Vault in your browser, where the current installers are.

To update, quit your DAW, run the new installer over the old version, and reopen. Updates are free and keep your activation.

19 · Troubleshooting

The tempo was detected wrong and the fills are all over the place.

Detection misses on some loops — usually by an octave (half or double time). Under the big BPM readout, click Src … · fix and type the loop's real tempo: the same audio is re-read on the right grid — nothing is stretched — and every fill rebuilds. Tips for getting it right first time: a tempo in the filename (loop_97.wav, 120bpm) is read automatically, captures from the DAW use your session tempo exactly, and a file trimmed to a clean 1- or 2-bar loop detects far more reliably.

Can I change the tempo of the loop itself?

Yes — click the main BPM readout and type a play-at tempo, or hit ½× / 2×. The whole phrase time-stretches to it (pitch preserved, attacks untouched): the bar, the fills, the previews and the WAV/MIDI exports all move together. While stretched, the readout shows the play-at tempo with Src 97 · reset under it; reset returns to the loop's own tempo. In the plugin this happens for you: loops follow the session tempo until you set a tempo manually, and the Host key turns following back on.

The plugin doesn't appear in my DAW after installing.

Fully quit and relaunch the DAW — most hosts scan at startup only. Ableton: Settings → Plug-Ins → make sure VST3 is enabled, then Alt/Option-click Rescan. Logic: it appears under AU → Yurt Rock (Logic occasionally needs a second launch to finish its AU validation).

Fill previews play through the wrong output (built-in speakers / display).

In the plugin, previews play through the plugin's channel and follow your DAW's audio device (builds from before August 2026 didn't — update if you see this). The one exception is a host that has stopped processing the track while its transport is stopped — then AU/VST3 previews go to your computer's default output until you press play (see Previews while the DAW is idle). In the standalone app, choose your interface under Options → Audio/MIDI Settings. In the browser, previews use the system default output (Mac: System Settings → Sound → Output; Windows: taskbar speaker icon). Exported audio is unaffected either way.

The standalone app is silent, or won't open my audio device.

Current builds check this at launch: if the device the app used last time is unplugged or can't run at its saved settings, the app falls back to your computer's default output (output only, if the input side can't open) so there's always sound. Pick your interface again under Options → Audio/MIDI Settings. Older builds could go silent and then reject every output you chose ("Couldn't open the output device!") — update if you see that.

Previews are silent in Pro Tools with the transport stopped.

Pro Tools may have suspended the plugin because its track is silent (Dynamic Plug-In Processing). Dr. Fill deliberately doesn't open your interface separately inside Pro Tools, so press play in Pro Tools, or turn Dynamic Plug-In Processing off in Setup → Playback Engine.

My Pro Tools session slowed down or the audio went wrong with the plugin inserted.

Earlier builds could open a second connection to your audio interface from inside Pro Tools, which could upset the session's clock. Current builds never do this in AAX — update to the latest version.

The Save button "does nothing."

It saves silently to your Downloads folder and flashes ✓ Saved on the button. If you don't see the flash, update to the latest version (re-download from the links above — updates are free and keep your activation).

Mac says the app "Requires macOS 26.0 or later."

That was a bug in builds before mid-August 2026, not a real requirement. Re-download from the Mac link above and reinstall — the current build runs on macOS 11+.

Windows: "MSVCP140.dll was not found" or a blank/error page inside the plugin window.

Both were fixed in current builds. Re-download from the Windows link above and run the installer again.

"Sign in with Yurt Rock" finished in the browser, but the plugin stayed on "Waiting for sign-in…"

Update to the current version: Dr. Fill now completes activation itself as soon as you sign in, and the browser page tells you whether it worked. If it still doesn't finish, click Cancel sign-in and try again, or activate with your serial number instead.

Sign-in says there's no membership or purchased license on the account.

Sign in with the same email you bought Dr. Fill with, or add your key to your account under Your Plug-Ins → Your Licenses — or simply paste the serial number into the plugin.

My serial says "invalid license."

Check for look-alike characters (the key uses no lowercase; paste rather than retype). If it still fails, reply to your purchase email — keys can be verified and reissued.

"Activation limit reached."

Free a slot at vault.yurtrock.com → Your Plug-Ins → Your Licenses → Deactivate on a machine you no longer use.

I lost my serial number.

If you added it to your Yurt Rock account, it's shown under Your Licenses. Otherwise it's in your purchase email — or reply to that email and we'll recover it.

My export is quieter or louder than the loop.

Check for fader automation: with a recorded curve and Read on, the moves print into the export. Switch Read off (or Clear) for the loop's own level. The Output fader's position on its own never changes exports.

Does updating cost anything or lose my activation?

No and no. Click Update available in the bottom-right corner (or use the links above), install over the old version, done. See Version & updates.

20 · Specifications

21 · Support

Stuck on something this page doesn't cover? Reply to your purchase email, use the questions / comments page (also linked from every tour card in the plugin), or reach us through yurtrock.com — a human reads everything.