Audio Engineering, DSP & Mastering Reference Portal

Practical audio engineering for producers who finish their own songs.

In-depth, measured guides to EQ, compression, limiting, mastering, loudness, gain staging, stereo imaging and room acoustics. Real values in Hz, dB, ms and LUFS, real signal chains, and the reasoning behind every move.

Browse all guides Delay & reverb calculator

−14 LUFSSpotify playback reference

−18 dBFSAnalog-plugin sweet spot

−1.0 dBTPSafe streaming ceiling

Vocal EQ: (1) HPF 80 Hz · (2) −3 dB @ 300 Hz · (3) −2.5 dB @ 3.2 kHz · (4) +2 dB shelf @ 11 kHz

Guides by category

Mixing, dynamics, mastering and DSP

Each guide is a complete reference: concepts, starting values, technical tables and a signal chain example you can rebuild in any DAW.

Mixing

Balance, tone and space: EQ decisions, vocal chains, low-end control, and reverb and delay that add depth without clutter.

MixingParametric EQ Frequency Guide: Cuts, Q Factor and PhaseA practical parametric EQ guide: high-pass slopes, mud at 200–400 Hz, presence and harshness, air, Q factor math, and minimum vs linear phase.10 min read MixingVocal Mixing Signal Chain: EQ, De-essing, Compression and SpaceA complete lead vocal chain: editing, subtractive EQ, 1176-into-LA-2A style serial compression, de-essing at 5–8 kHz, saturation, plate reverb and slap delay.6 min read MixingLow End Management: Kick, Bass and 808 Without the MudWho owns the sub, tuning 808s, phase alignment between kick and bass, sidechain ducking vs dynamic EQ, mono below 120 Hz and harmonics for small speakers.7 min read MixingReverb and Delay: Creating Depth Without Washing Out the MixReverb types, pre-delay and decay, EQ on returns, tempo-synced delay times, slapback, throws and ducking, and how to place sounds front to back.6 min read

Dynamics

Compressors and limiters explained at the level of real settings: ratios, attack and release in milliseconds, true peak ceilings and LUFS.

DynamicsAudio Compression Explained: Threshold, Ratio, Attack and ReleaseHow a compressor works, what attack and release really do, VCA vs FET vs Opto vs Vari-Mu, parallel compression and starting settings by source.8 min read DynamicsTrue Peak Limiting and LUFS: Loudness for Streaming and ClubsBrickwall limiters, inter-sample peaks, -1.0 vs -0.3 dBTP ceilings, integrated LUFS, and how Spotify, YouTube, Apple Music and club systems handle loudness.8 min read

Mastering

Taking a mix to release: headroom, references, multiband control, clipping versus limiting, dither, and finishing AI-generated songs.

MasteringMastering Chain Workflow for Home StudiosA step-by-step mastering workflow: -6 dB headroom, references, corrective EQ, multiband dynamics, stereo imaging, clipping vs limiting and dither.8 min read MasteringFinishing AI-Generated Songs: Mixing and Mastering for ReleasePractical steps for cleaning up songs made with AI music generators: rights, stems, separation artifacts, harsh highs, baked-in reverb, re-recording and mastering.6 min read

Acoustics & DSP

The technical foundation: gain staging, stereo and phase, room acoustics and monitoring, and the plugins you actually need.

Acoustics & DSPGain Staging and Headroom: dBFS, dBVU and the -18 dBFS Sweet SpotHow to set healthy levels from recording to the master: dBFS vs dBVU, the -18 dBFS reference for analog-modeled plugins, 32-bit float and internal clipping.7 min read Acoustics & DSPStereo Imaging and Phase Correlation: Wide Mixes That Work in MonoPanning, mid/side encoding and decoding, the Haas effect and comb filtering, reading a phase correlation meter from +1 to -1, and checking mixes in mono.6 min read Acoustics & DSPHome Studio Acoustics and Monitoring: Room Modes, Placement and LevelsWhy small rooms lie about bass, how to calculate room modes, speaker placement, first reflections, basic treatment, safe monitoring levels and mixing on headphones.6 min read Acoustics & DSPEssential Audio Plugins: What You Actually Need to Mix and MasterThe plugin categories that matter, why stock plugins are enough for most work, free plugins worth installing, formats, latency and CPU management.6 min read

Quick reference

Frequencies and loudness at a glance

The numbers that come up in almost every session. Use them as starting points, then trust your ears and your meters.

Frequency quick reference
Range	What lives there	Common move
20–60 Hz	Sub: 808 and kick weight	High-pass non-bass tracks; keep mono
60–250 Hz	Kick body, bass, vocal chest	Carve kick vs. bass, one owns the sub
200–400 Hz	Warmth and mud	2–4 dB cuts spread across tracks
400 Hz–1.5 kHz	Boxiness, nasal tone	Narrow cuts only where it rings
2.5–4 kHz	Presence and harshness	Dynamic EQ on loud passages
5–8 kHz	Sibilance, cymbal edge	De-esser, 3–6 dB on worst "s" sounds
10–20 kHz	Air and breath	High shelf +1 to +3 dB after de-essing

Loudness and level standards
Context	Reference	Notes
Spotify (Normal)	−14 LUFS	Keep true peak under −1 dBTP
YouTube	≈ −14 LUFS	Loud tracks are turned down
Apple Music	≈ −16 LUFS	Applied with Sound Check
Club / DJ masters	−9 to −6 LUFS	No normalization on club systems
EBU R128 broadcast	−23 LUFS	Maximum −1 dBTP
Analog-modeled plugins	−18 dBFS ≈ 0 VU	Average level into the chain
Mix before mastering	−6 to −3 dBFS	Peak headroom, no master limiter

Platform reference levels are commonly documented values and can change. See the true peak and LUFS guide for context.

Interactive tool

Delay & Reverb Time Calculator

Enter a tempo, use the +/− buttons, or tap along to the song. The tables update instantly with straight, dotted and triplet delay times in milliseconds, LFO rates in Hz, and tempo-synced reverb pre-delay and decay values.

Tempo (BPM)

Quarter note at 120 BPM = 500 ms

Delay times
Note	Straight	Dotted	Triplet	Rate
1/1 (whole / 1 bar)	2000 ms	3000 ms	1333.3 ms	0.50 Hz
1/2	1000 ms	1500 ms	666.7 ms	1.00 Hz
1/4	500 ms	750 ms	333.3 ms	2.00 Hz
1/8	250 ms	375 ms	166.7 ms	4.00 Hz
1/16	125 ms	187.5 ms	83.3 ms	8.00 Hz
1/32	62.5 ms	93.8 ms	41.7 ms	16.00 Hz
1/64	31.2 ms	46.9 ms	20.8 ms	32.00 Hz

Reverb pre-delay and decay
Space	Total length	Pre-delay	Decay
Hall / long tail (total 1 bar, pre-delay 1/32 note)	2000 ms 1 bar	62.5 ms 1/32 note	1937.5 ms
Plate / large room (total 1/2 note, pre-delay 1/64 note)	1000 ms 1/2 note	31.2 ms 1/64 note	968.8 ms
Small room (total 1/4 note, pre-delay 1/128 note)	500 ms 1/4 note	15.6 ms 1/128 note	484.4 ms
Tight ambience (total 1/8 note, pre-delay 1/128 note)	250 ms 1/8 note	15.6 ms 1/128 note	234.4 ms

How the numbers are calculated

One quarter note lasts 60,000 ÷ BPM milliseconds, and one bar of 4/4 lasts four times that. A dotted note is 1.5 times the straight value, and a triplet is two thirds of it. The rate column converts each straight note value to Hz (1,000 ÷ milliseconds), which is useful for syncing tremolo, auto-pan or filter LFOs on plugins without a tempo-sync option.

For reverb, the pre-delay is set to a short note value and the decay fills the rest of the chosen length, so pre-delay plus decay equals the total. The tail then ends close to where the next beat or phrase begins. Plugins measure decay differently (many use RT60, the time to fall by 60 dB), so treat these values as a starting point and fine-tune by ear in the mix.

Studio Tip

On vocals, start with a 1/4 or dotted 1/8 delay low in the mix, high-passed around 300 Hz and low-passed around 5 kHz. If the echoes clutter the lyrics, duck the delay return with a sidechain from the dry vocal. The reverb and delay guide explains the full setup.

About SUNO.click

An independent reference written and tested by a working audio producer and mixing engineer. No sponsored recommendations, no hype: settings are worked through on real material, compared at matched loudness and checked on several playback systems.

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