Owl — User Guide | Audubon Audio

1

Two Plugins, One System

Owl is two separate VST3 plugins that work together: Owl Carrier and Owl Receiver. Carrier acts as a silent measurement tap — it sits in your FX chain, captures the audio at that point, and continuously transmits level data to the Receiver via a fast inter-process link. It does not change the sound at all.

Receiver displays both the Carrier's measurements and its own measurements side by side, so you can compare levels at two different points in your signal path in real time. It also has tools to match the loudness between the two positions automatically.

2

Carrier Must Be Upstream of Receiver

The order matters. Carrier must process audio before Receiver does in the DAW's signal flow. Think of it as: Carrier reads the level first, then passes that reading to Receiver which reads the level second. If the order is reversed, Receiver will detect this and show an error.

Owl Carrier

upstream ← place here

→

Your FX Chain
EQ · Comp · Limiter

→

Owl Receiver

downstream ← place here

You can also place Carrier and Receiver on two completely different tracks. As long as they share the same sample rate, block size, and channel count, they will find each other automatically when you press play.

Owl Carrier and Receiver placed in an FX chain with processing between them

3

Setting Up — Step by Step

Follow these steps to get Owl running on your session:

Step 1

Insert Owl Carrier into your FX chain at the position where you want to measure the source level — typically first in the chain, before your processing.

Step 2

Insert Owl Receiver later in the same FX chain — or on a different track entirely — at the position where you want to measure the result level.

Step 3

Press Play in your DAW. Both plugins activate and find each other. The Receiver's status bar turns green and reads LINKED — Carrier sending level data.

Step 4

Let audio play for at least 5 seconds with signal present on both tracks. The Avg Diff panel on the right of the Receiver will finish analyzing and show the level difference between the two points.

1

Carrier Interface

Carrier is intentionally minimal — a small window with a status indicator and a single button. All the measurement display lives in the Receiver. Carrier's only job is to measure audio at its position and transmit the data.

The colored dot on the left of the status card shows the link state at a glance. The SHOW OWL RECEIVER button brings the Receiver window to the front in your DAW without having to hunt for it — useful when you have many plugins open.

Linked — transmitting to Owl Receiver
Carrier and Receiver have found each other and are communicating. Everything is working correctly.

[!] Carrier is AFTER Receiver — move Carrier earlier
The plugin order is wrong. Carrier is running after Receiver in the signal chain. Move Carrier to an earlier slot in the FX chain, or an earlier track in the session.

Not linked — press Play to activate
Carrier hasn't found a Receiver yet. Make sure Receiver is loaded on the same session, press Play, and wait a moment.

Owl Carrier plugin window with green linked status indicator

1

Three Meter Columns

The Receiver window is divided into three vertical columns, each showing a different signal position. All meters refresh at 30 fps.

Carrier (cyan)

Measurements captured at the Carrier's position in your chain — the "before" signal.

Receiver (emerald)

Measurements at the Receiver's own position — the "after" signal.

Match (purple)

Measurements of the Receiver's output after any Match Gain correction has been applied. Shows the net result of matching.

Owl Receiver three-column layout showing Carrier, Receiver, and Match meter columns

2

What Each Meter Row Means

Both the Carrier and Receiver columns display the same seven rows. Understanding what each row tells you is the key to using Owl effectively.

Peak dB

The instantaneous sample peak level in dBFS. This is the highest single sample value in the most recent processing block. Very reactive — it reflects transients accurately but clears quickly. Use this to watch for clipping (anything approaching 0 dBFS).

Max Peak hold

The highest peak seen since the last reset. It only ever goes up — it holds the worst-case transient from your entire session. Use this to confirm the signal has never clipped. Reset it with the RESET ALL HOLDS button when you want a clean reading from this point forward.

RMS 300ms

The root-mean-square average level measured over a rolling 300ms window. RMS reflects perceived loudness better than peak alone because it tracks the energy of the signal over time. Compare the Carrier and Receiver RMS values to see how much your processing has changed the overall level.

LUFS Momentary

ITU-R BS.1770 momentary loudness measured over a 400ms sliding window. This is the standard used by streaming platforms to measure loudness. Cyan for Carrier, emerald for Receiver. Watch this number to ensure you are hitting target streaming levels (typically −14 LUFS for most platforms).

LUFS Mom Max hold

The highest momentary LUFS value reached so far, held until reset. Use this to see the loudest moment of your track and compare it across the Carrier and Receiver — your limiter or compressor should be pulling this down relative to the Carrier's reading.

LUFS Short-term

ITU-R BS.1770 short-term loudness measured over a 3-second sliding window. Slower to respond than momentary — it gives a stable reading of the average loudness of a section. More useful for evaluating overall mix balance than for catching individual transients.

LUFS ST Max hold

The highest short-term LUFS reading held since last reset. Because short-term is already a 3-second average, this max value gives a reliable sense of the loudest sustained section of your audio — useful for checking loudness ceiling compliance.

Hold values are always amber. Any row labeled with "(hold)" or "Max" in the Receiver will display in amber and only increase — it never decreases on its own. When you want a fresh measurement from a specific point in time, press RESET ALL HOLDS and the hold values on both Carrier and Receiver clear simultaneously.

3

How to Read the Level Bars

Each column has a vertical level bar alongside its numeric readouts. The bar has two layers: a filled level bar that tracks the RMS level in real time, and a peak tick mark near the top that shows the instantaneous peak. When the peak tick approaches the top of the bar, the signal is near 0 dBFS. When the Carrier bar is noticeably taller than the Receiver bar, your processing is attenuating the signal — as expected from a compressor or limiter.

A Receiver bar that is taller than the Carrier bar means your processing is adding gain somewhere in the chain between the two plugins. This might be intentional (a boost EQ, a makeup gain on a compressor) or accidental.

1

Avg Diff Panel — Understanding the Number

In the bottom-right corner of the Receiver is the Avg Diff (30s) panel. This shows the rolling 30-second average difference between the Carrier RMS and the Receiver RMS, updated every 5 seconds. It reads Carrier RMS minus Receiver RMS:

Positive value (+X.X dB)

"Carrier is louder" — the signal at the Carrier's position is louder than at the Receiver's. Your FX chain is attenuating the signal. This is normal when using a compressor or limiter between the two.

Negative value (−X.X dB)

"This plugin is louder" — the signal has been boosted between Carrier and Receiver. This happens when a makeup gain or boost EQ is in the chain.

Near zero (±0.5 dB)

"Levels matched" — the average loudness at both positions is essentially the same. No level correction is needed.

Analyzing... (pulsing)

The plugin is collecting data. It needs at least 1 second of audio above −60 dBFS on both channels before it can calculate. Wait for audio to play and the reading will appear within 5 seconds.

2

Reset All Holds

The RESET ALL HOLDS button clears every max/hold value on both the Carrier and Receiver columns at once. The Receiver sends a reset signal to the Carrier through the shared link, so both plugins clear simultaneously — you do not need to open the Carrier window separately.

Use this whenever you want to start a fresh measurement: after setting levels, after making a major change to your chain, or at the beginning of a new pass. All amber hold values drop back to −inf immediately.

3

Match Volume (Manual)

Once the Avg Diff panel has collected enough data (at least ~5 seconds of audio), the MATCH VOLUME button becomes active. Clicking it reads the current Avg Diff value and applies that exact dB correction as a gain offset on the Receiver's output.

For example: if the Avg Diff shows +3.2 dB (Carrier is louder), clicking Match Volume applies +3.2 dB to the Receiver's output, bringing it up to match the Carrier's average level. The Match meter column shows the result after correction is applied.

The gain readout below the buttons shows the currently applied correction: Correction applied: +3.2 dB. This correction is a fixed offset — it does not adapt as levels change. Use Auto Match if you need the correction to stay current as you make adjustments.

Typical workflow: Insert Carrier before your compressor/limiter, Receiver after. Play your track for 30 seconds. Click Match Volume. Now both positions are loudness-matched — A/B between bypassing and enabling your FX chain is a fair comparison because the level difference is removed. You are comparing the effect of the processing, not the level difference it creates.

4

Auto Match (Continuous)

AUTO MATCH keeps the level correction continuously updated rather than applying a fixed snapshot. It uses a fast exponential moving average that measures the RMS difference between Carrier and Receiver every ~50ms and updates the applied correction every ~500ms. The status bar reads LINKED — Auto Matching Volume Active in purple when it is running.

This is most useful when you are actively tweaking compressor or EQ settings and you want the Receiver's output to stay loudness-matched to the Carrier continuously as you make changes. Without Auto Match, every parameter change that affects the output level would throw off a manual Match Volume correction.

Click AUTO MATCH again to toggle it off, or click CLEAR to both stop Auto Match and remove the applied correction entirely. The button label changes to AUTO MATCH ON while active.

5

Clear

CLEAR removes all applied gain correction — both manual Match Volume and Auto Match — and returns the Receiver to unity gain. The Match meter column returns to showing the uncorrected Receiver level. Use this when you want to go back to comparing raw unmatched levels or when you have made a large change to your chain and want to re-analyze from scratch.

A

All Status States Explained

The status bar at the bottom of the Receiver window tells you exactly what is happening between the two plugins.

LINKED — Carrier sending level data
Everything is correct. Both plugins are communicating. Meters are live and accurate.

LINKED — Auto Matching Volume Active
Linked and Auto Match is running. The Receiver is continuously adjusting its output gain to match the Carrier's level.

[!] No Carrier found — place Owl Carrier before this plugin
Receiver cannot find a Carrier. Either Carrier is not in the session, or both plugins are not running at the same sample rate and block size. Check that Carrier is loaded and that you have pressed Play.

[!] Carrier is downstream — move Carrier earlier in chain
Receiver detected that Carrier is processing audio after it, not before. Swap the plugin order in your FX chain, or move the Carrier track earlier in your session's processing graph.

[!] Multiple Carriers detected — only one allowed per track
More than one Owl Carrier instance is running with the same configuration. Remove the duplicate Carrier. Each Carrier/Receiver pair must be unique.

A

Level-Matched A/B of Your FX Chain

Place Carrier at the very start of your FX chain (before any processing). Place Receiver at the end. Play for 30 seconds. Click MATCH VOLUME. Now bypass your entire FX chain in the DAW — the bypassed signal hits the Receiver first (which passes it through without the correction applied since the plugin is active but the chain is bypassed) vs. the full processed version.

The standard approach: keep both Carrier and Receiver active, then use your DAW's FX chain bypass to toggle the processing between them. Because Match Volume compensates for the output level difference the processing creates, what you are hearing when you toggle is the processing quality alone — not the level change it introduces. This is how professional engineers do level-matched A/B comparisons.

B

Monitoring Pre/Post Compression or Limiting

Place Carrier before your compressor or limiter, Receiver after. Watch the LUFS Short-term readings in both columns while audio plays. The difference between Carrier short-term and Receiver short-term tells you how many dB of loudness reduction the compressor is producing on average over 3 seconds. The RMS 300ms comparison tells you the moment-to-moment gain reduction.

Enable AUTO MATCH and then adjust the compressor's threshold or ratio. Because the output level is continuously corrected, what you are hearing through the Receiver reflects the effect of the compressor's tonal and dynamic shaping — not its loudness change. This lets you dial in exactly the right amount of compression by ear without the louder output biasing your perception.

C

Loudness Compliance Check

Place Receiver after your master limiter. Watch the LUFS Momentary and LUFS Short-term values in the Receiver column during playback. These are the numbers streaming platforms measure. For Spotify, Apple Music, and most major streaming services the target is around −14 LUFS integrated — your short-term readings should be in this neighborhood during the loudest sections of your track.

Use the Max Peak hold row to confirm that your limiter is keeping the true peak below −1 dBFS (the standard headroom requirement for streaming). If Max Peak ever reaches 0 dBFS or above, your limiter is not catching all inter-sample peaks.

D

Cross-Track Level Comparison

Place Carrier on a reference track (a professional mix you are comparing against) and Receiver on your own master bus. Both tracks must have the same sample rate and block size. The Receiver shows the reference track's levels in the Carrier column and your own master bus levels in the Receiver column simultaneously. Use this to see at a glance whether your master's LUFS, RMS, and peak readings are in the same territory as the reference.