Crypta — User Manual

Split your bass. Compress the lows. Twist the guts out of the highs.

What it is

Crypta is a Parallax-style parallel bass processor built for metal production. As of v0.2.0 it splits your bass signal into three bands — low, mid, and high — with two cascaded 4th-order Linkwitz-Riley ("LR4") crossovers, keeps the low band tight with a parallel compressor, drives the mid band with staged saturation, and runs the high band through a choice of three distortion voicings before summing everything back together through a 4-band EQ and a cabinet-simulation IR loader.

Research-derived rebuild (v0.2.0)

v0.2.0 is a research-driven rewrite of v0.1.x's simpler two-band (low/high) topology, sourced against the reference plugin class's own official user manual, a third-party professional review, the same design lineage's hardware product manual, and general parallel-bus-compression community/vendor consensus — not measured against any reference plugin's actual audio output, DSP source code, or hardware unit by this project. See docs/design-brief.md and docs/research-notes.md for the full sourcing, and the same disclosure v0.1.x already carried: voicing character (drive-gain ranges, mid-filter hump/scoop settings) is engineering-tuned, not yet finalized by ear against reference material.

Where it sits in a heavy-music chain

Crypta is designed to be the bass-specific voicing stage in the Basilica Audio suite:

Track order: DI/amp sim → Crypta → bus compression/glue → mix bus. It expects a reasonably clean, already-amp-sim'd or DI'd bass signal; it is not itself a full amp sim (no built-in preamp gain staging beyond the input trim and drive controls).
The low band's parallel compressor is meant to keep the fundamental/sub content of the bass locked in place under a wall of distorted guitars. The mid band adds a distinct "throatier" saturation character that sits in the frequency range most likely to clash with a guitar wall — dial it in deliberately, not just as an afterthought. The high band's voicing adds the upper-mid/high "grind" that lets the bass cut through a dense mix.
Two independent split points (Split Low, Split High) let you tune both crossover corners across the low-mid register to match the song's tuning (drop-tunings push useful low-end content further up) and to control how wide the mid band's "throat" is.
The output stage's IR loader — now applied only to the Mid+High path, never the Low band — is meant for quick cabinet-style tone shaping without needing a separate cab-sim plugin later in the chain, though it can also be left off entirely if you're already running a dedicated cab sim elsewhere.

Signal flow

Input Trim → Gate → LR4 Split Low (60–400 Hz, default 120 Hz)
                      │
        ┌─────────────┴───────────────────────────────┐
        │                                              │
     Low band                              Remainder → LR4 Split High (300–2000 Hz, default 600 Hz)
  Parallel Comp → Level                                  │
        │                          ┌───────────────────┴───────────────────┐
        │                       Mid band                              High band
        │                    Drive → Level          Tight → Voicing → Drive → Tone → Blend → Level
        │                          └───────────────────┬───────────────────┘
        │                                          Mid+High sum
        │                                                │
        │                                          IR loader (cab sim)
        │                                                │
        └───────────────────────┬────────────────────────┘
                                 │
                       Sum (delay-compensated)
                                 │
                            4-band EQ
                                 │
                       Safety Clip (optional)
                                 │
                               Output

The Mid and High bands share the same oversampling anti-aliasing headroom (each 4x oversampled independently, but identically configured, so they report identical latency); the low band carries a matching compensation delay, plus a phase-alignment allpass filter tied to Split High's own cutoff, so all three bands sum flat and stay time-aligned at the final sum. The IR loader (cabinet simulation) sits after the Mid+High sum and before the final three-way sum — the Low band never passes through it, matching the reference class's "low band bypasses the cabsim" architecture. See docs/architecture.md for the full technical breakdown, including exactly how the latency and phase-alignment compensation work.

Presets

Crypta ships with a preset system: a horizontal bar at the top of the plugin window lets you step through factory and user presets (< / preset name / >), save/save-as/delete your own, and import/export single presets or preset banks (zip files of multiple presets). Nine factory presets ship in v0.2.0 — see docs/presets.md for what each one demonstrates. User presets are stored per-plugin under:

macOS: ~/Library/Audio/Presets/Yves Vogl/Crypta/
Windows: %APPDATA%\Yves Vogl\Crypta\Presets\

A fresh instance loads a user "Default" preset if you've saved one ("Set current as default" in the preset menu), otherwise the factory "Default" preset (matching the plain parameter defaults documented below).

Parameter reference

Unless noted otherwise, all continuous parameters are smoothed to avoid zipper noise when automated.

IO / Global

Parameter	Range	Default	Unit	What it does
Input Gain	−24 … +24	0	dB	Trims the signal before anything else in the chain. Use this to get a hot but not clipping signal into the gate/compressor/drive/voicing stages - all of their thresholds are calibrated assuming a reasonably "line level" input.
Output Gain	−24 … +24	0	dB	Final output trim, applied after everything else (including the safety clip).
Bypass	off/on	off	—	Forces a bit-exact passthrough of the input signal. Also exposed as the plugin's host-facing bypass parameter, so your DAW's own bypass button/automation lane works too.
Safety Clip	off/on	off	—	A soft (tanh) limiter on the very last stage before the output trim. Off by default; turn it on as a safety net against accidental hard-clipped overs, not as a tone-shaping tool - at typical playing levels it's inaudible, and it only starts rounding peaks once they approach 0 dBFS.

Noise Gate (full-band, before the crossover splits)

Sits ahead of both crossovers, so it gates the input signal as a whole rather than per band.

Parameter	Range	Default	Unit	What it does
Gate Enable	off/on	off	—	Enables the gate. Off by default - most already-tracked bass DI/amp signals don't need one, and an incorrectly-set gate can chop off legitimate low-level playing (ghost notes, decays).
Gate Threshold	−80 … 0	−60	dB	Signal level below which the gate starts attenuating.
Gate Ratio	1 … 20	10	:1	How aggressively the gate attenuates once below threshold. Higher = closer to a hard mute.
Gate Attack	0.1 … 50	1	ms	How fast the gate opens once the signal crosses back above threshold.
Gate Release	5 … 500	100	ms	How fast the gate closes once the signal drops below threshold.

Split Low / Split High (two cascaded crossovers, NEW topology in v0.2.0)

Parameter	Range	Default	Unit	What it does
Split Low	60 … 400	120	Hz	The LR4 split point between the Low band and everything above it. Log-scaled control. Lower it to push more of the fundamental into the (compressed-only) Low band; raise it to give the Mid band more low-mid content to work with.
Split High	300 … 2000	600	Hz	The LR4 split point between the Mid band and the High band. Log-scaled control.

Split High is always kept at least a fraction of an octave above Split Low internally (a reasoned safety margin against a degenerate near-zero-width Mid band) — if you push the two close together, Split High's effective value will float slightly above whatever you've set Split Low to, rather than collapsing the Mid band to nothing.

Low band: parallel compressor + level

The low band is compressed in parallel: the compressed signal is blended back with its own uncompressed self via Mix, rather than replacing it outright, which is what keeps the low end feeling tight and controlled without ever sounding squashed or lifeless. v0.2.0 re-sources the ballistics defaults to the reference class's own fixed, sourced values — a fast, gentle "glue" bus compressor, not the heavier "New York style" squash v0.1.x's defaults implied (see docs/research-notes.md §3–4 for the full sourcing).

Parameter	Range	Default	Unit	What it does
Low Comp Threshold	−60 … 0	−18	dB	Level above which the low-band compressor engages.
Low Comp Ratio	1 … 20	2	:1	Compression ratio above threshold.
Low Comp Attack	0.1 … 100	3	ms	How fast the compressor clamps down once above threshold.
Low Comp Release	5 … 1000	6	ms	How fast the compressor lets go once back under threshold. Range floor lowered from 10 ms in v0.1.x so the sourced 6 ms default is reachable.
Low Comp Makeup	−12 … +24	0	dB	Gain applied to the compressed (wet) signal before it's blended back with the dry low band - use this to bring the compressed signal back up to match the dry level, so Mix behaves as a true "how much compression character" control rather than also changing overall loudness.
Low Comp Mix	0 … 100	100	%	Blend between the dry (uncompressed) and wet (compressed + makeup) low band. 0% = compressor has no audible effect; 100% = fully compressed.
Low Level	−24 … +12	0	dB	Level trim on the low band, applied after compression and before the bands are summed back together.

Mid band: drive + level (NEW in v0.2.0)

A dedicated mid band with staged/cascaded saturation, structurally similar to the High band's Wool voicing (two cascaded soft-clip stages) but with no filter, tone, or blend control of its own — matching the reference class's own Mid band exactly ("Mid Drive... Mid Level" only). This band's job is a distinct "throatier" grind character, separate from the High band's own presence/fuzz/harshness-control role.

Parameter	Range	Default	Unit	What it does
Mid Drive	0 … 100	30	%	Staged saturation amount. 0% is an exact passthrough; increasing it blends progressively toward a fully cascaded-tanh-driven signal.
Mid Level	−24 … +12	0	dB	Level trim on the mid band, applied after drive and before the bands are summed back together.

High band: Tight, voicing, drive, tone, blend, level

Three selectable distortion voicings, each 4x oversampled to keep the nonlinear shaping stage's aliasing out of the audible band.

Parameter	Range	Default	Unit	What it does
High Tight	20 … 500	100	Hz	NEW in v0.2.0: a pre-drive high-pass filter, now applied ahead of every voicing (was a Razor-only fixed 200 Hz internal constant in v0.1.x). This is the primary "how much fuzz vs. tightness" control for the whole High band, and also tames harshness on high-drive settings - pull it down toward its floor for maximum fuzz, push it up for a tighter, more controlled top end.
High Voicing	Gnaw / Wool / Razor	Gnaw	—	Selects the distortion character. See below.
High Drive	0 … 100	50	%	How hard the signal is pushed into the selected voicing's nonlinearity.
High Tone	0 … 100	50	%	Post-shaper tone control: a low-pass sweeping from dark (0%) to bright (100%), tucking away or opening up fizz/harshness from the distortion stage.
High Blend	0 … 100	100	%	Blend between the clean (pre-voicing) and fully distorted high band. 0% = clean high band (voicing has no audible effect); 100% = fully distorted.
High Level	−24 … +12	0	dB	Level trim on the high band, applied after voicing/blend and before the bands are summed back together.

Voicings:

Gnaw — an op-amp-style hard clip. Symmetric, unforgiving, the most aggressive of the three; pushes hard into a square-ish waveform at high drive. Good for a raw, buzzy attack.
Wool — cascaded soft-clip fuzz with a mid scoop and a touch of asymmetry for a grittier, more fuzz-pedal-like harmonic character. Good for a woolier, less "digital" grind that still cuts.
Razor — a tighter overdrive: a comparatively mild clipper, with a mid-hump filter afterwards that keeps the low end from ever getting mushy (the pre-clip highpass duty is now handled band-wide by Tight, above, rather than being Razor's own quirk as in v0.1.x).

Starting points, not final voicing: the drive-gain ranges and mid-filter hump/scoop settings for all three voicings are engineering defaults, tuned for musical usefulness and mathematically bounded (no runaway output at any drive setting), not yet finalized by ear against reference material. Expect these to be refined in a future release.

Post-sum 4-band EQ

Applied after all three bands are summed back together (and after the IR loader). Off by default; when off, the EQ stage is skipped entirely (guaranteed transparent, not just set to unity gain). v0.2.0 re-anchors the default corner frequencies to a sourced bass-tone-stack frequency set from the same design lineage as the reference class (v0.1.x's defaults were unsourced placeholders).

Parameter	Range	Default	Unit	What it does
EQ Enable	off/on	off	—	Enables the EQ stage.
EQ Low Shelf Frequency	40 … 400	80	Hz	Low shelf corner frequency.
EQ Low Shelf Gain	−18 … +18	0	dB	Low shelf boost/cut.
EQ Peak 1 Frequency	100 … 2000	500	Hz	First parametric peak band's centre frequency.
EQ Peak 1 Gain	−18 … +18	0	dB	First peak band's boost/cut.
EQ Peak 1 Q	0.2 … 5.0	0.7	—	First peak band's bandwidth (higher = narrower).
EQ Peak 2 Frequency	500 … 8000	2800	Hz	Second parametric peak band's centre frequency - a "presence/definition" high-mid anchor.
EQ Peak 2 Gain	−18 … +18	0	dB	Second peak band's boost/cut.
EQ Peak 2 Q	0.2 … 5.0	0.7	—	Second peak band's bandwidth.
EQ High Shelf Frequency	2000 … 16000	5000	Hz	High shelf corner frequency.
EQ High Shelf Gain	−18 … +18	0	dB	High shelf boost/cut.

IR loader (cabinet simulation)

A convolution-based cab-sim stage that now processes only the Mid+High post-sum signal (relocated in v0.2.0 - it sat post-everything in v0.1.x). Off by default. With no impulse response loaded, this stage is a guaranteed bit-exact passthrough at every session sample rate, so turning it on before loading an IR never changes your sound. The Low band is structurally never passed through this stage, matching the reference class's "low band bypasses the cabsim" architecture - your fundamental/sub content stays uncolored regardless of what cab IR you load.

Parameter	Range	Default	Unit	What it does
IR Enable	off/on	off	—	Enables the IR loader stage.
IR Mix	0 … 100	100	%	Blend between the dry (pre-convolution) and fully convolved Mid+High signal.

Loading impulse responses: v0.2.0 still does not ship an in-plugin file browser or factory cabinet IRs (both remain on the roadmap for a later milestone alongside the custom GUI). The IR-loading DSP engine itself is fully implemented and real-time safe.

State migration (v0.1.x → v0.2.0)

If you open a Crypta v0.1.x session, the old single Crossover Frequency value is migrated to the new Split High parameter, clamped into its new 300–2000 Hz range (v0.1.x's own shipped default, 250 Hz, is below that floor, so an untouched v0.1.x session lands exactly at 300 Hz on reopen). Split Low and every new Mid-band/Tight parameter fall back to their v0.2.0 defaults. Any low-band compressor settings you had explicitly changed away from v0.1.x's old defaults are preserved as-is — only the shipped default changed, not your own deliberate settings. This is a best-effort, lossy, one-directional migration; re-check your low/mid/high balance after reopening an old session.

Tips

Start with the low band tight, then dial in the mid band's throat, then the high band's grind. Set Low Comp Mix and Makeup first so the fundamental feels locked in, then dial in Mid Drive for the "throatier" cutting character, and only then pick a High voicing and drive amount.
Split Low and Split High are tone decisions, not just technical ones. Pushing Split Low up moves more note body out of the (compressed-only) Low band; pushing Split High up widens the Mid band's own passband, giving the "throatier" character more room before the High band's own fuzz/presence character takes over.
High Tight is your main "fuzz vs. tightness" control, independent of which voicing you've picked - pull it toward its 20 Hz floor for maximum fuzz, push it up toward 500 Hz for a tighter, more controlled top end. It also tames harshness on hot Drive settings.
High Blend is your "how much" knob, High Drive is your "how hard" knob. If a voicing feels too extreme, try lowering Blend before lowering Drive - you'll often keep more of the character that way, just at a lower overall intensity, rather than flattening the nonlinearity itself.
Leave the safety clip off during tracking/mixing, and only reach for it as insurance against unexpected automation or a hot input on a specific pass - it's a safety net, not part of the intended tone-shaping signal path.