REAPER mix analysis — find what's wrong and how to fix it

Drop a bounce from REAPER and Unveil tells you why it isn't sounding pro yet — loudness, dynamics, tonal balance, phase, and frequency conflicts — then gives you fixes written for REAPER's own stock plugins. No third-party plugins to buy — just a free account to try it.

REAPER's engine and what its meters mean

REAPER mixes in 64-bit floating point by default, so a master channel showing positive dB values is not clipping inside the project. The master meter shows peak levels, with a clip indicator that latches when the output exceeds 0 dBFS; click it to reset. Because the engine has so much internal headroom, REAPER will happily let you build a mix that is loud on the master and only reveal the problem on render.

Track meters are configurable: right-click the meter for options such as peak versus RMS display and the meter range. Choose a range that makes the top 20 dB readable, so you can see how a track sits in relation to others without squinting.

The pan law is a project setting and can differ between projects and templates. If you import a project or template from someone else, check the project settings first so that centered mono elements keep the level you expect.

A bare-bones toolkit that does the job

ReaEQ is a parametric equalizer with an unlimited number of bands, each switchable between types such as band, shelf, high-pass, low-pass and notch. Its built-in spectrum display is plain but functional. ReaComp is a flexible compressor with a detector pre-filter, RMS or peak windowing, lookahead and sidechain, which is something many other stock compressors lack. ReaLimit is a lookahead limiter with a threshold and ceiling, perfect as the last device in the chain. ReaXcomp offers multiband compression for the occasional frequency-specific problem.

JSFX are text-script effects that load instantly and use almost no CPU. REAPER ships many, including utility tools like polarity inversion, mid/side encoding and a loudness meter that measures peak, RMS and LUFS. The LUFS meter is the one to put on the master: play the song through and read the integrated value, then compare it with roughly -14 LUFS for Spotify and YouTube, or roughly -16 LUFS for Apple Music.

The honest tradeoff is polish: REAPER's stock plug-ins look utilitarian, and their strength is accuracy and flexibility. Many experienced mixers use them for the entire mix.

Rendering: the dialog where mistakes hide

Choose File, then Render. The Source should be Master mix, the Bounds should cover the whole song with a short tail added to catch reverb decay, and the output format should be WAV. Pick a 24-bit depth for a pre-master and the project sample rate unless asked otherwise.

The render dialog offers options to dither the master mix and to normalize or limit the output. For analysis, leave normalization off. Dither is for final reduction to 16-bit only. If you use the loudness-based normalization option to hit a target, understand that it applies gain to the whole file, so peaks move with it: raising loudness by 3 dB also raises the true peak by 3 dB.

REAPER can also run a render that doesn't write a file but reports statistics such as peak and loudness values for the master mix. If your version provides this, it is a quick way to check numbers without creating files. Check the render dialog options in your version.

Worked fix: a mix that is too quiet and too peaky

Suppose the render measures -17.5 LUFS integrated and a true peak of -0.2 dBTP. The song is both quiet and over the safe ceiling, which can only be explained by a few sharp transients, typically the snare or a vocal consonant, sticking out well above the average level.

1. Put ReaLimit (or another limiter) on the master and set its ceiling to -1.0 dB.
2. Lower the threshold until the loudest transients register 1 to 2 dB of gain reduction. Do not exceed 3 dB on a mix that still has dynamics.
3. Play the whole song and read the JSFX loudness meter. Each dB of threshold reduction adds roughly a dB of level; to get from -17.5 to about -14 LUFS you need around 3.5 dB of net gain, which may be more than a limiter can give cleanly.
4. If you have to reduce more than 3 to 4 dB, go upstream: use ReaComp on the drum bus (ratio 3:1, attack 10 ms, release 80 ms) to bring the peaks down before they hit the master.
5. Re-render and check again. A target of -14 LUFS with -1 dBTP is realistic for most pop and rock; denser genres may sit at -10 or louder by choice.
6. If the song becomes fatiguing, reduce the target by 1 to 2 dB. Streaming services will turn it down anyway.

Folders, routing and the sum

REAPER treats folders as tracks that can sum their children, so a drum folder behaves as a drum bus with its own FX chain. The same flexibility lets you build confusing routing with sends and parent/child connections. When a signal is both in a folder and sent separately, it is counted twice, and the mix may be louder than expected.

• Use a consistent structure: instruments into folders, folders into the master.
• Look at the routing window for any track with unexpected sends.
• Remember that each plug-in in a chain can add latency; the Performance meter shows the PDC contribution and helps catch parallel chains that are misaligned and cause comb filtering.

Typical REAPER mistakes

• Assuming the master meter is accurate for true peak. It reads sample peaks; keep a margin of at least 1 dB.
• Rendering with Normalize enabled from an earlier project's render preset, which silently rescales the file.
• Trusting the default of a rendering preset that includes a different sample rate than the project.
• Using parallel compression sends without compensating for latency, creating phase problems in the low end.
• Leaving dither on for a 24-bit render because the preset was saved for CD delivery.

Checklist

Measure the render once more after every correction rather than relying on the meters inside the session.

• Confirm pan law and project sample rate when opening a project from elsewhere.
• JSFX loudness meter on the master, read across the whole song.
• ReaLimit ceiling at -1.0 dB; no more than 3 dB of reduction on a still-dynamic mix.
• Render source Master mix, normalize off, 24-bit, dither only for 16-bit.
• Render statistics or an external analysis on the final file.

What you get

• A 0–100 mix score with a per-metric breakdown (LUFS, true peak, dynamic range, stereo, tonal balance).
• Time-localized frequency conflicts — the exact moment and band where elements collide.
• Step-by-step fixes using ReaEQ, ReaComp, and ReaLimit — e.g. a corrective ReaEQ band at the flagged frequency.
• Genre-aware targets so a trap bounce isn't judged against an acoustic record.

Questions

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