Built-In Processors, Phase Alignment & CLAP Plugins

12-Band Parametric EQ with Dual-Trace Spectrum Analyzer, Analog VCA Compressor, Tape Saturation, Convolution Reverb, Stereo Tape Delay, Multi-Mic Phase Alignment, and CLAP plugins.

Every Input Track (CH01 through CH18) and every stereo Subgroup Bus (SUB 1 through SUB 16) in Cave Recorder includes a dedicated, reorderable 8-Slot Processing Rack powered by zero-latency 64-bit internal studio processors alongside external .clap plugin hosting, automatic multi-mic phase alignment, and dedicated stereo Auxiliary Returns.

This chapter covers the dual-view inspection workflow (Upper Console Wells vs. full-screen CHANNEL INSPECTOR), the Tape Saturation (TAPE) stage, the 12-Band Parametric EQ & Dual-Trace Spectrum Analyzer (EQ & RTA), the Analog VCA Compressor (VCA COMPRESSOR & GR), the Stereo Convolution Reverb (AUX 1 REVERB) and Stereo Tape Delay (AUX 2 TAPE DLY), Automatic Multi-Mic Phase & Polarity Alignment (ALIGN ALL & Φ), and CLAP Audio Plugin Hosting (1:CLAP, PDC & Low-Latency Monitoring).

5.1 Upper Console Wells vs. Dedicated CHANNEL INSPECTOR View#

Cave Recorder provides two complementary workspaces for viewing and shaping the processors on any Input Track or Subgroup Bus:

1. The Four Upper Console Wells (MIX CONSOLE View, CMD/CTRL + 1): Docked permanently along the upper deck of the Mix Console so you can adjust inserts, EQ curves, and compression while keeping all channel faders and bus meters in view.
2. The Dedicated CHANNEL INSPECTOR View (CMD/CTRL + 3): Expands the selected channel or subgroup across the entire screen with a high-resolution Dual-Trace Real-Time Spectrum Analyzer, dedicated rotary parameter knobs, multi-bus output routing popovers, and a scrolling Gain Reduction history trace.

5.1.1 The Four Upper Console Wells (MIX CONSOLE)#

Clicking any Input Track header (CH01..CH18) or clicking the SEL button on any Subgroup Bus (DRUM BUS, INST BUS) immediately binds the four Upper Console Wells to that strip:

5.1.2 Full-Screen CHANNEL INSPECTOR View (CMD/CTRL + 3)#

Pressing CMD + 3 (macOS) or CTRL + 3 (Windows/Linux) switches to the dedicated CHANNEL INSPECTOR view. Along the top selector bar, single-click pills (01 Kick In, 02 Snare Top, 03 Overhead L, 04 Guitar Amp, DRUM BUS, INST BUS) let you step across every Input Track and Subgroup Bus in the session without returning to the Mix Console.

In the CHANNEL INSPECTOR view, the left column anchors a full-height channel strip (complete with active Pass selector * PASS 01 on Input Tracks or STEREO SUBGROUP / SUBGROUP BUS badges on Subgroups, Output Bus selector, M, S, REC, MON, Ø, Φ, TRIM, rotary PAN, full-scale calibrated meter with +12 dB to -48 dB markings, and CLR CLIP), while the main workspace expands:

• EQ & DUAL-TRACE 4096-PT RTA: Adds direct band-select buttons for all 12 bands (B1 through B12), all seven filter shape buttons (BELL, LSHF, HSHF, HPF, LPF, NTCH, TILT), and dedicated precision rotary knobs on the right (FREQ, GAIN, Q).
• VCA COMPRESSOR & GR TRACE: Adds a continuous scrolling Gain Reduction (GR Trace) timeline, extended ratio and parallel blend buttons (SC HPF, LINK, 2:1, 4:1, 8:1, 20:1, MIX 100%, MIX 50%), and six dedicated rotary knobs on the right (THRESH, RATIO, ATTACK, RELEASE, MAKEUP, MIX).
• Multi-Bus Output Routing Popover: Clicking the green OUT: MST or crimson OUT: SUB 1 button in the left inspector strip opens the OUTPUT BUSES popover ([x] MASTER BUS, [ ] SUB 2: INST BUS), allowing any track or subgroup to feed multiple buses in parallel.
• Bottom Track Waveform & Pass Action Bar: Below the compressor graph, the inspector waveform strip provides quick Pass Lane actions for the active Take: PASSES (or E) expands Pass Lanes, PASS 01 selects the active pass, AUD P1 auditions that pass in isolation, MUTE P1 mutes the pass, and DEL P1 deactivates and hides the pass from playback.
• Dedicated Inspector Keyboard Shortcuts: While inspecting any strip, press H to toggle the compressor Sidechain High-Pass Filter (SC HPF), X to clear the channel peak overload latch (CLR CLIP), E to expand or collapse Pass Lanes (PASSES), or SHIFT + M / S / A / I / P to toggle Mute, Solo, Record Arm, Input Monitor, or Polarity (Ø).

5.1.3 Reordering the 8-Slot Rack, SWAP EQ/CMP & RESET#

In Well 1 (01 Kick In or DRUM BUS), the eight processing slots (1 through 8) execute sequentially from Slot 1 down to Slot 8:

• Clicking a Slot Pill to Assign Built-In Processors: Clicking any slot pill (1 through 8) opens the rack slot assignment picker, where you can assign any of the built-in zero-latency studio processors (12-Band Dynamic EQ, VCA Compressor, Tape Saturation, or Aux Send Tap) or clear the slot to Empty / Bypassed (---).
• Dragging :: or Clicking ^ / v: Reorders any processor (1:CLAP, 2:12B EQ, 3:VCA CMP, 4:AUX SND) to an earlier or later slot in real time without audio clicks or dropouts. Moving 4:AUX SND above 3:VCA CMP, for example, taps the channel's Aux Sends before compression even when the send is set to rack-tap mode.
• SWAP EQ/CMP Button: Instant one-click macro in the top-left rack header that swaps the slot positions of the 12B EQ and VCA CMP processors. Use SWAP EQ/CMP to audition whether filtering low-end mud before the compressor detector (EQ -> CMP) or shaping tonal balance after dynamic peak control (CMP -> EQ) sounds more natural on a vocal, bass, or drum bus.
• B (Slot Bypass) & RESET: Clicking B next to any slot (or on the 12B EQ / VCA CMP badge) bypasses that single processor in place (illuminated amber). Clicking the crimson RESET button returns all built-in processors on the selected strip to their flat factory defaults.

5.2 Tape Saturation & Input Drive (TAPE)#

Located in Well 1 beneath the 8-slot rack, the built-in Tape Saturation (TAPE) processor models the non-linear magnetic hysteresis, transformer core warmth, bias asymmetry, and head-bump high-frequency roll-off of a calibrated analog multitrack tape machine running at 15 or 30 IPS.

Click the TAPE pill in the Well 1 header to engage or bypass the tape stage on the selected Input Track or Subgroup Bus.

5.2.1 Tape Saturation Parameter Reference#

5.2.2 Studio Tape Recipes for Tracking & Mixing#

5.3 12-Band Parametric EQ & Dual-Trace Spectrum Analyzer (EQ & RTA)#

Each Input Track and Subgroup Bus features a precision 12-Band Parametric Equalizer (2:12B EQ) paired with a Dual-Trace High-Resolution Real-Time Spectrum Analyzer (EQ & DUAL-TRACE 4096-PT RTA). Designed for zero-zipper-noise live adjustment, the equalizer handles everything from steep sub-bass rumble filtering and surgical snare-ring notch removal to broad, musical spectral tilt shaping.

5.3.1 12-Band EQ Parameter & Filter Shape Reference#

5.3.2 Operating Interactive EQ Nodes & Reading the Dual-Trace RTA#

You can shape EQ either via the right-hand rotary knobs (FREQ, GAIN, Q) in the CHANNEL INSPECTOR view (CMD/CTRL + 3) or by manipulating the colored band nodes directly inside the EQ & RTA graph on both the Mix Console and Channel Inspector:

• Click + Drag Node Horizontally / Vertically: Sweeps FREQ (20 Hz to 20 kHz) and GAIN (-24.0 dB to +24.0 dB) simultaneously.
• Mouse Scroll Wheel (or SHIFT + Vertical Drag) Over a Node: Narrows or widens the filter Q (0.10 to 18.00).
• SHIFT + Drag Node: Engages 10x fine precision (0.1 dB gain steps and sub-Hz frequency resolution) for locking onto exact room resonances.
• Double-Click Node (or OPT/ALT + Click): Resets the band's GAIN to 0.0 dB.

Behind the white composite EQ curve, the Dual-Trace High-Resolution Real-Time Spectrum Analyzer (4096-PT RTA) renders two live acoustic traces simultaneously:

1. Pre-EQ Input Spectrum (Darker Shaded Trace): Shows the raw frequency energy entering the 12B EQ slot.
2. Post-EQ Output Spectrum (Bright Emerald Trace): Shows the resulting frequency energy leaving the 12B EQ slot after all active bands are applied.

Because the high-resolution analyzer resolves narrow intervals down into the lowest bass octaves (20 Hz to 250 Hz), you can visually distinguish between the 55 Hz fundamental of a kick drum and the 82 Hz low E string of a bass guitar, place a narrow BELL or NTCH node directly on a ringing 480 Hz snare overtone spike, and watch the emerald post-EQ trace flatten out in real time. On any record-armed track (R), the Dual-Trace RTA remains active even when software Input Monitoring (I) is turned off, allowing you to inspect live microphone spectrum and dial in high-pass or notch filters during zero-latency hardware direct-monitoring sessions.

5.4 Analog VCA Compressor & Gain Reduction Meter (VCA COMPRESSOR & GR)#

The Analog VCA Compressor (3:VCA CMP) models a classic studio voltage-controlled amplifier dynamics processor (inspired by large-format British console bus compressors and fast American VCA limiters). It combines punchy transient control with a built-in Sidechain High-Pass Filter (SC HPF, shortcut H in the Channel Inspector) and New York Parallel Mix (MIX) stage.

5.4.1 VCA Compressor Parameter Reference#

5.4.2 Interactive Transfer Curve & Real-Time Gain Reduction (GR) Trace#

The VCA COMPRESSOR & GR graph displays input level (-48 dB to 0 dB) on the horizontal axis against output level (-24 dB to 0 dB) on the vertical axis:

• Interactive Threshold & Knee Nodes: Drag the highlighted gold node along the diagonal line to set THRESH, and drag the upper slope handle (or click 2:1, 4:1, 8:1, 20:1) to tilt the compression ratio above threshold.
• Scrolling Gain Reduction (GR Trace): As audio passes through the compressor, a shaded crimson trace sweeps across the graph showing instantaneous and historical gain reduction depth in decibels. Watching the GR Trace alongside the waveform makes it easy to dial ATTACK and RELEASE so the compressor breathes cleanly between snare hits or vocal phrases.

5.4.3 Studio Starting Settings for Common Sources#

5.5 Stereo Convolution Reverb (AUX 1 REVERB) & Stereo Tape Delay (AUX 2 TAPE DLY)#

To keep CPU overhead near zero while providing authentic vintage studio ambience during live tracking and mixing, Cave Recorder provides two dedicated stereo Aux Return processors fed by the RVB and DLY send bars on every Input Track and Subgroup Bus.

5.5.1 AUX 1 REVERB: Zero-Latency Acoustic Convolution Reverb#

AUX 1 REVERB uses a zero-latency real-time acoustic convolution engine (FFT CONV IR / ZERO-LATENCY) loaded with studio impulse responses, headed by the classic EMT 140 Plate alongside Studio Wood Room, Live Stone Chamber, and Vintage Spring Tank spaces.

5.5.2 AUX 2 TAPE DLY: Capstan Analog Tape Delay#

AUX 2 TAPE DLY models a multi-head magnetic capstan tape echo unit (CAPSTAN TAPE / TAPE ECHO) complete with mechanical transport wow and flutter, oxide saturation, high-frequency head damping, and stereo ping-pong regeneration.

5.6 Automatic Multi-Mic Phase & Polarity Alignment (ALIGN ALL & Φ)#

When recording a drum kit, guitar cabinet, acoustic piano, or horn section with multiple microphones, physical distance differences between capsules create acoustic arrival-time offsets. Sound travels through studio air at approximately 343 meters per second (1,125 feet per second), meaning every 34.3 cm (13.5 inches) of extra distance between a close microphone and an overhead or room microphone delays the acoustic wavefront by 1.0 millisecond (1000 microseconds, or 48 samples at 48.0 kHz).

5.6.1 Why Multi-Mic Time Offsets Cause Comb Filtering & Hollow Low End#

When two microphones capture the same instrument at slightly different arrival times and are summed together on DRUM BUS or MST MASTER BUS:

• Frequencies whose half-wavelength matches the time offset arrive 180° out of phase and cancel each other out, carving deep, hollow notches across the frequency spectrum (known as comb filtering).
• A snare drum captured by both 02SnrTp (close dynamic mic) and 03OvrhdL (condenser mic 63 cm / 25 inches above the snare) suffers a 1.85 ms (1850 us) arrival delay at the overhead capsule. Without phase alignment, summing the overheads with the close snare mic thins out the 200 Hz snare body and smears the initial stick transient into a double flam.
• Similarly, a snare bottom microphone pointed upward at the snare wires moves in the opposite mechanical direction from the top snare microphone, requiring a 180° polarity inversion (Ø) in addition to time alignment.

5.6.2 Running ALIGN ALL & Auditioning with PHASE: ALIGN / PHASE A/B#

Cave Recorder eliminates manual waveform sliding and guesswork through its built-in Sub-Sample Multi-Mic Phase & Polarity Alignment engine:

1. Record a Short Pass or Play Back an Existing Take: Have the drummer play the full kit for a few bars (or load any recorded Take on the timeline).
2. Click ALIGN ALL in the Top Deck (or Φ ALIGN ALL on the Console Bar): Cave Recorder analyzes the active Take's recorded multi-track Broadcast Wave .wav files on disk (or the live rolling capture memory if no recorded Take files exist yet) using sub-sample bandpass (150 Hz to 6 kHz) GCC-PHAT cross-correlation within a +-25 ms acoustic window, delaying closer microphones forward in time to match the furthest reference microphone. The entire multi-track phase and polarity alignment operation is captured as a single undoable step so you can revert or reapply it at any time with CMD/CTRL + Z.
3. Inspect Per-Channel Ø and Φ Readouts: Within milliseconds, each aligned channel strip updates its header telemetry and phase buttons:
   • Ø (Cyan Polarity Badge, SHIFT + P on inspected strip): Engages automatically on any channel whose acoustic waveform is inverted 180° relative to the reference microphone (such as CH02 02SnrTp or a bottom snare mic).
   • Φ (Emerald Phase Align Badge) & Microsecond Readout: Engages sub-sample time alignment (0.00 ms to +50.00 ms, displayed in microseconds from 0us to 50000us, such as 420us on CH02 and 1850us on CH03) so all wavefronts arrive at the subgroup summing bus at the exact same sub-sample instant.
4. A/B Audition Globally (PHASE: ALIGN / PHASE A/B): Click the emerald PHASE: ALIGN button in the Top Deck (or the PHASE A/B button on the Mix Console toolbar) to toggle all phase and polarity corrections in and out across the entire console simultaneously. You will immediately hear the kick and snare low-end punch tighten up and the stereo center image snap into focus. Both Run Multi-Mic Phase Alignment and Toggle Global Phase A/B can also be bound to custom keyboard shortcuts in the KEYMAP view (CMD/CTRL + 6).

5.7 Hosting External CLAP Audio Plugins (1:CLAP, PDC & Low-Latency Monitoring)#

While Cave Recorder's built-in TAPE, 12B EQ, VCA CMP, AUX 1 REVERB, and AUX 2 TAPE DLY processors cover 95% of studio tracking and mixing tasks with zero added latency, any of the eight insert slots (Slots 1..8) on any Input Track or Subgroup Bus can also host third-party CLAP (Clever Audio Plug-in, .clap) effects processors.

5.7.1 Scanning & Loading .clap Plugins into the 8-Slot Rack#

Cave Recorder automatically scans the standard operating system CLAP plugin directories on startup:

• macOS: /Library/Audio/Plug-Ins/CLAP and ~/Library/Audio/Plug-Ins/CLAP
• Windows: C:\Program Files\Common Files\CLAP and %LOCALAPPDATA%\Programs\Common\CLAP
• Linux: ~/.clap and /usr/lib/clap

To manage slots and CLAP plugin processing on an Input Track or Subgroup Bus:

1. Select the target track or click SEL on the target Subgroup Bus, then look at the 8-slot rack in Upper Well 1 (CMD/CTRL + 1) or the left column of CHANNEL INSPECTOR (CMD/CTRL + 3).
2. Click any slot (1 through 8) to open the slot assignment picker for built-in zero-latency processors (12-Band Dynamic EQ, VCA Compressor, Tape Saturation, Aux Send Tap, or Empty / Bypassed), or click an active 1:CLAP slot pill to inspect the hosted plugin. (Note: Interactive per-slot selection of third-party external .clap plugins from the rack picker is scheduled for a post-v0.1.0 release with a dedicated Plugin Manager.)
3. Use the slot's :: drag handle or ^ / v arrows to position the 1:CLAP slot anywhere in the signal chain (for example, placing 1:CLAP ahead of 2:12B EQ and 3:VCA CMP).
4. Click the slot's B button at any time to bypass the slot in place.

5.7.2 Automatic Plugin Delay Compensation (PDC) & Transparency Breakdown#

All built-in Cave Recorder processors (TAPE, 12B EQ, VCA CMP, AUX 1 REVERB, AUX 2 TAPE DLY) operate with zero internal sample latency (0 smp / 0.00 ms). However, when you insert a third-party CLAP plugin that uses internal lookahead buffering (such as linear-phase equalizers or lookahead limiters), that plugin reports its processing delay (in samples) to Cave Recorder.

To prevent phase cancellation or timing drift between parallel tracks and subgroups, Cave Recorder performs Automatic Plugin Delay Compensation (PDC) across the entire mixing graph:

• The Top Deck displays a live PDC: N smp (X.XX ms @ 48 kHz) status pill at all times.
• Clicking the PDC pill in the Top Deck opens the Latency & PDC Transparency Breakdown popover (shown in Figure 5.4 above), which reports every latency stage in your studio system in both Samples (smp) and Milliseconds (ms):
  • Audio I/O: Current hardware buffer size (256 frames @ 48000 Hz), input buffer latency (In: 64 smp / 1.33 ms), output buffer latency (Out: 64 smp / 1.33 ms), and calibrated hardware Roundtrip I/O (640 smp / 13.33 ms).
  • Total Graph PDC & Effective Playback PDC: Total delay compensation applied across parallel tracks and buses (Max Safe Ceiling: 96,000 smp / 2000.00 ms).
  • Playhead Lag & Overdub Record-Offset: Exact negative sample offset (-640 smp / 13.33 ms) applied automatically when writing new Overdub Passes (Rec002-OD) to disk so that everything a musician plays against playback lands sample-accurately on the timeline.
  • Filterable Per-Channel Table (ALL, ARMED, COMPENSATED, BYPASSED): Lists every Input Track (Track 1 [ARMED]..Track 18), Subgroup 1..2, Aux 1 (Reverb), Aux 2 (Delay), and Master Bus with its individual sample and millisecond compensation state.

5.7.3 Low-Latency Monitoring During Overdubs#

When you are late in a mix and have inserted a high-latency lookahead mastering plugin or linear-phase EQ on a track or Subgroup Bus, recording a last-minute vocal or guitar overdub through that high-latency plugin would introduce a distracting echo in the musician's headphones.

Clicking Low-Latency Monitoring in the Top Deck solves this immediately:

• Cave Recorder temporarily bypasses high-latency CLAP plugins only on record-armed (R) live monitoring paths and their downstream buses, dropping the musician's headphone monitoring latency back down to pure zero-latency built-in console processing (0 smp graph PDC).
• All unarmed playback tracks continue playing with full Plugin Delay Compensation.
• As soon as you finish recording the Overdub Pass and disarm the track (or toggle Low-Latency Monitoring off in the Top Deck), the high-latency CLAP plugins re-engage automatically without losing a single plugin parameter setting.