Help Wiki & User Manual (v4.0.99)

Welcome to the official GAAP (Guitar Android Audio Processor) documentation. This guide details every component of GAAP's real-time C++ audio DSP engine, guitar amplifiers, live looper, 4-track mixer, Song Studio DAW, and AI backing track generator.

1. Audio Engine, Latency & Auto-Device Protection

GAAP is powered by an industry-first Dual-Tier Native C++ Audio Architecture engineered to deliver studio-grade, near-zero round-trip latency on both flagship and budget Android devices:

• Tier 0: Direct User-Space USB-C Stack (Low-Latency Hardware Bypass):
  • For non-flagship chipsets (e.g. MediaTek Helio G85, entry-level Exynos) or USB interfaces that encounter Android OS HAL bottlenecks (such as Focusrite Scarlett 4th Gen multi-channel routing, PreSonus AudioBox dual-rate microframes, and Hi-Fi USB-C dongles), GAAP completely bypasses Android's ALSA audio server.
  • Communicates directly with USB hardware endpoints via Linux kernel transfers, delivering direct 48kHz / 24-bit pro-audio streaming with <6ms hardware latency and zero OS audio buffer bloat.
• Tier 1: High-Performance Oboe & AAudio Subsystem:
  • On standard and flagship Android devices with certified low-latency HALs, GAAP leverages Google's AAudio and OpenSL ES backend with dedicated real-time thread affinity and automatic CPU core pinning.
• Interactive Latency Status Pill: Located prominently at the top of the main screen, the pill indicates your current audio safety level:
  • Latency: Optimized (Green): The audio engine is running at ultra-low buffer sizes (~3ms to 12ms round-trip depending on device DAC and USB backend).
  • Latency: Safe Mode (Tap to Optimize) (Yellow): Buffer sizes are cushioned to guarantee glitch-free playback on mid-range or busy devices. Tapping the pill opens the latency configuration dialog.
• Latency Multiplier Settings: Accessible via the top toolbar Settings (Gear Icon) or by tapping the Latency Pill. Choose from 6 buffer scaling profiles:
  • Insane Low Latency (Multiplier 1): Absolute fastest response for high-end flagships (Google Pixel, Samsung Galaxy S, OnePlus).
  • Extreme / Ultra Low Latency (Multiplier 2–3): Recommended for USB audio interfaces (Focusrite Scarlett, iRig HD 2, PreSonus, Montarbo, M-Audio).
  • Low / Medium / High Latency (Multiplier 4–8): Safe fallbacks for older devices or high-load background tasks.
• Smart Auto-Device Reconnect: If your USB-C interface cable is accidentally tugged or unplugged while playing:
  • GAAP instantly silences the engine to protect your hearing and speaker cones from sudden feedback or loud pops.
  • The moment you re-insert the USB cable, GAAP automatically dismisses the disconnect alert and triggers the AUDIO DEVICE picker dialog for you, allowing you to resume playing in a single tap!
• Feedback Shield: When using the phone's built-in speaker and microphone simultaneously, GAAP activates the Feedback Shield to mute the live guitar signal and prevent runaway howling squeals. Connecting headphones or a USB interface instantly unlocks two-way audio.
• Bluetooth Latency Warning: While GAAP supports Bluetooth outputs, a persistent warning pill (⚠️ Bluetooth Connected (~200ms Latency)) reminds you that the Bluetooth protocol introduces ~150–250ms of unavoidable wireless delay. A wired USB-C audio interface or adapter is strictly recommended for live guitar monitoring.

2. Chromatic Tuner

GAAP includes a studio-grade, high-precision chromatic tuner needle driven by an 8192-point Fast Fourier Transform (FFT) and Harmonic Product Spectrum (HPS) pitch detection algorithm.

• Needle & Cent Display: Displays exact detected frequency in Hertz (Hz), closest musical pitch note (e.g. E2, A2, D3, G3, B3, E4), and smooth analog-style meter rotation with +/- 50 cents deviation.
• Pre-Gate Raw Signal Routing: The tuner receives the pure raw guitar signal before any noise gates or high-gain distortion pedals, ensuring lightning-fast pitch tracking on low strings (Low E at 82.4 Hz) even with quiet acoustic picking.
• Mute / Live Toggle: Tap the Tuner Mute button to tune in complete silence during live stage performance, or tap Live to hear your guitar tone while checking tuning.

3. Preamps, Power Amps & Cabinet Simulation

GAAP features an authentic, component-modeled tube guitar amplifier stack featuring dedicated Preamp, Power Amp, and Impulse Response (IR) Cabinet stages.

Preamp Simulator (PRE SIM)

Shapes your primary tone, harmonic distortion, and EQ curve before hitting the modulation and time-based pedals:

• JTM45 Freeware: Classic vintage British blues-rock warmth with creamy mid-range breakup.
• Plexi Subscription / Rewarded Ad: Legendary Marshall 1959 Super Lead crunch and aggressive high-gain bite.
• Bassman Subscription / Rewarded Ad: American tweed warmth with thick bottom-end and glassy clean headroom.
• Twin Reverb Subscription / Rewarded Ad: Sparkly, pristine American blackface cleans with scooped mids.
• AC30 Subscription / Rewarded Ad: Chimey British Class-A tone with sparkling top-end jangle.
• JCM800 Subscription / Rewarded Ad: The definitive 1980s hard rock and heavy metal roaring crunch.
• Rectifier Subscription / Rewarded Ad: Modern American ultra-high-gain dual rectifier wall of sound with crushing low-end.

Controls: Gain, Bass, Middle, Treble, Presence, and Output Level.

Power Amp Emulation

Emulates vacuum tube power stages (EL34, 6L6, EL84) with adjustable Amp SAG (dynamic power supply voltage drop under heavy transients for organic compression) and Presence high-frequency shelf.

Cabinet Simulator (CAB SIM)

Simulates real-world speaker cabinets and microphone placement:

• Tweed 1x12 Freeware: Focused, vintage open-back combo speaker tone.
• Blackface 2x12 Subscription / Rewarded Ad: Wide, balanced American combo projection.
• AC30 2x12 Subscription / Rewarded Ad: British Alnico Blue chime and mid-range punch.
• Marshall 4x12 Subscription / Rewarded Ad: Iconic closed-back stack with massive low-end punch and roaring mid resonance.
• Recto 4x12 Subscription / Rewarded Ad: Oversized modern 4x12 cab tuned for drop-tunings and tight metal chugs.

Controls: Mic Position (center cap to edge cone sweep), Room Ambience, and Microphone Type selection.

4. The Guitar Effects Chain

The signal path in GAAP flows sequentially through a professional virtual pedalboard. Each pedal can be toggled on/off or opened via its settings gear icon.

Dynamics & Boost

• Boost Freeware: Transparent clean gain booster with Mix, Gain, Tone, and Output Level controls.
• Sustain Subscription: Studio compressor with Mix, Sustain, Attack, Release, and Output Level controls.

Noise Gate

Clamps down on high-gain hiss and single-coil hum with adjustable Threshold and Reduction parameters. Freeware

Overdrive & Fuzz Stompboxes

• Mid-Hump & Clipping Freeware: Classic TS9 Tube Screamer mid-boost and hard-clipping distortion.
• Transparent, Fab, SD1, Vintage Fuzz Subscription: Klon Centaur clean blend, Boss SD-1, and silicon/germanium fuzz clipping.

Tone Shaper (6-Band Post-Drive Graphic EQ)

Surgical 6-band graphic equalizer positioned directly after the drive pedals to sculpt mid-range bite or dial out harsh fizz before time-based effects. Freeware

Modulation (Reorderable Pedal Chain)

The modulation section lets you reorder effects by dragging them in the signal chain:

• AutoWah: Dynamic envelope-following filter (Classic Freeware, Modern, Custom Subscription).
• Tremolo: Volume pulsing (Optical Freeware, Sine, Harmonic Subscription).
• Phaser: Multi-stage analog phase shifting (Phase 90 Freeware, Small Stone, Modern 8-stage Subscription).
• Flanger: Jet-plane sweeps and through-zero phase cancellation (Electric Mistress Freeware, ADA, Through-Zero Subscription).
• Chorus: Rich spatial doubling (CE-1 Freeware, Small Clone, Dimension, Tri-Chorus, Detune Subscription).

Delay (Time-Based Echoes)

GAAP's delay algorithms reproduce everything from clean digital repeats to analog tape flutter and pitch-shifted shimmer trails. Each model includes independent Mix and Feedback controls:

• Mono, Stereo, Ping-Pong Freeware: Crisp digital, wide dual-channel, and stereo alternating echoes.
• Tape, Shimmer, Reverse, Multi-Tap, Modulated, Echo Subscription: Analog tape saturation with high-cut damping, pitch-shifted octave shimmer, and reverse echoes.

Reverb (Acoustic Space Simulation)

• Spring & Plate Freeware: Vintage amp spring drip and classic metal plate reflections.
• Hall, Room, Algorithmic, Shimmer, Cloud Subscription: Expansive orchestral concert halls, celestial shimmer octaves, and ambient cloud reverb.

Haas Double Tracker

Splits a mono guitar into a wide, spatial 4-track stereo wall of sound using psychoacoustic micro-delay offsets. Freeware

Global Master EQ

Master output sculpting featuring Graphic 6-Band Freeware, Graphic 12/24-Band, and fully sweepable 4-Band Parametric EQ Subscription.

5. 4-Track Live Mixer & MIDI Backing Tracks

GAAP includes a dedicated 4-Track Live Mixer directly beneath the Song Studio banner on the main screen, allowing you to jam alongside backing tracks with full control over the mix:

• Independent Track Channels: Dedicated volume faders and mute/solo toggles for:
  • DRUMS (Drum kit audio)
  • BASS (Bass line synth / audio)
  • PIANO (Keyboards and harmony chords)
  • MELODY (Lead guitar / vocal guide tracks)
• Live vs. Backing Balance Slider: Seamlessly adjust the master balance between your live guitar tone and the backing band volume.
• Custom MIDI Import (.mid) with Smart Track Selection: Tap Load Song → Import MIDI to load any standard multi-track MIDI file from your device storage.
  How does Smart Track Selection & Auto-Routing work?

  Standard MIDI files often contain 16 or more overlapping channels (strings, brass, multiple keyboard layers, sound effects, rhythm guitars) that would sound cluttered or cause frequency mud if played simultaneously. GAAP's intelligent Musical Smart Routing engine automatically analyzes every discovered track in the MIDI file and assigns the optimal roles into the 4-track mixer:

  • DRUMS: Automatically detects General MIDI Channel 10 (ch 9) and scans track names for percussion keywords (drum, kit, perc, bongo, conga).
  • BASS: Evaluates pitch depth, note density, and program changes to isolate the single best bassline groove with the lowest fundamental frequency.
  • MELODY: Analyzes monophonic vs. polyphonic chord ratios and vocal registers (D3 to A5) to find the primary lead/vocal guide line (prioritizing tracks named vocal, lead, solo, theme). You can also transpose this melody (+12, -12, or -24 semitones) to match your vocal range or guitar tuning!
  • PIANO / HARMONY: Automatically selects the cleanest chordal accompaniment track to provide rich harmonic backing.
  • AUTO-IGNORE CLUTTER: All remaining extraneous or duplicate tracks are automatically set to IGNORE, preventing frequency clashes and keeping your backing track punchy and mix-ready!

  Manual Override: In the MIDI Track Routing dialog, you can preview the song with interactive Play/Stop transport controls, listen to the arrangement, tap ✨ Smart Auto Route to reset to AI recommendations, or manually reassign any track to any mixer role using intuitive dropdown spinners!

6. Synchronized & AI-Powered Live Looper

GAAP features a synchronized phrase looper with 3 operational modes:

• 1. Classic Looper Mode: High-fidelity loop recording with unlimited overdub layers. When Sync is engaged, loop start and endpoints automatically quantize to the Drum Sequencer measure grid to eliminate timing drift.
• 2. Auto Drums Mode (AI Jammer): Strum your progression naturally. The AI engine listens to your live tempo and dynamic transients to automatically generate a synchronized, human-feeling drum beat.
• 3. Auto Drums + Bass Mode (AI Jammer): The full trio experience. The engine continuously detects both tempo and pitch scales in real-time, driving a synchronized drum groove and a polyphonic FM Bass Drone Synth that harmonizes alongside your guitar chords!

Accompaniment Customization: Select from dozens of curated cultural styles (Rock, Blues, Jazz, Metal, Latin, Balkan, Flamenco, Middle Eastern), context-aware odd time signatures (e.g. 7/8, 9/8), and tailored bass synth voices (Smooth Bass Guitar, Slap Bass, or Church Organ).

7. Song Studio DAW & AI Song Generator

Tap the SONG STUDIO (Open ->) banner on the main screen to enter GAAP's integrated 4-track digital audio workstation:

• Timeline Sequencer: Construct full song arrangements by organizing structured sections (Intro, Verse, Chorus, Bridge, Solo, Outro).
• Multi-Track Piano Roll & Step Grid: Edit drum triggers, bass lines, and keyboard harmonies step-by-step with individual note velocity and swing parameters.
• AI Song Generator: Let GAAP's AI compose an entire song blueprint for you! Choose a genre, key, tempo, and measure count, and the AI generator assembles complete multitrack arrangements in seconds.
• Project Import/Export (.dsg): Save, back up, and share your complete Song Studio projects as .dsg files.

8. HD Jam Video Recorder & Social Export

Capture your guitar solos and jam sessions with pristine studio audio directly on your device:

• Direct Studio Audio Recording: Tap the Camera icon in the top toolbar to reveal the Jam Recorder. Unlike standard phone camera apps that record muffled room audio through the mic, GAAP captures the clean, processed digital audio directly from the DSP engine!
• Source Selection Switch: Choose between recording your Wet Guitar Only (perfect for mixing into external DAWs) or the full Master Mix (Guitar + Drums + Backing Tracks).
• Hardware Video Muxer & Watermark: Upon finishing a take, GAAP uses hardware-accelerated MediaMuxer and FFmpeg to combine 1080p camera video with uncompressed 48kHz stereo audio, producing ready-to-share MP4 clips for YouTube Shorts, Instagram Reels, and TikTok!

9. Preset Management (.gaapfx)

Save and recall your exact tone configurations, including every knob value, amplifier model, and custom pedal order:

• Preset Carousel: Quickly switch between factory and custom presets (e.g. 80s Hysteria Clean, Back In Black Rhythm, Black Strat Soaring Lead).
• Export & Share (.gaapfx): Export your tones as standalone .gaapfx or .json files to share with friends or back up to cloud storage.
• Community Submissions: Want your custom preset featured in the official GAAP library? Email your exported .gaapfx files to victorhantelmann@gmail.com with your artist name!

10. BPM Speed Trainer & Masterpiece Mastery

The BPM Speed Trainer is not just a metronome incrementer—it is an intelligent pedagogical practice suite designed to systematically build your musical confidence, fretboard dexterity, and shredding velocity across any musical passage.

Train Over Sequences or Individual Measures

A major breakthrough of GAAP's Trainer is its granular architectural flexibility. You are never forced to rehearse an entire song from start to finish when working on a difficult lick:

• Sequence-Level Looping: Loop specific structural sections of a song (such as the Guitar Solo, Fast Bridge Riff, or Chorus Progression) repeatedly until the transition becomes second nature.
• Measure-by-Measure Isolation: Zoom in on the single most technically challenging measure or 2-measure turnaround. Slow down that exact phrase, loop it seamlessly, and hear every subdivision of the backing tracks clearly before attempting it at full speed.

Practice Against Web Masterpieces & Custom MIDI Backing Tracks

Combine the BPM Speed Trainer with the 4-Track Live Mixer and MIDI Import feature:

• Master Any Classic Solo: Download standard MIDI files of legendary guitar masterpieces from the web (e.g., Pink Floyd, Van Halen, Metallica, Dream Theater) or export your own guitar compositions from Guitar Pro or your desktop DAW.
• Isolate and Slow Down the Band: Load the song, isolate the backing tracks with the 4-track mixer (muting the original guide guitar so only your live guitar cuts through), and slow down the playback to 40% or 50% tempo to dissect complex fast runs note-for-note.
• Gradual Speed Buildup: Configure the Trainer to automatically increment tempo by a small, imperceptible amount (e.g., +2 to +5 BPM every 2 or 4 loops). Because the speed increases automatically without touching your phone, you never have to take your hands off the fretboard or break your physical picking flow.
• Over-Speed Confidence Training: Push the Trainer beyond the target recording tempo (e.g., practice a 120 BPM solo up to 135 or 140 BPM). When you finally return to the original 120 BPM tempo during a live gig or studio recording, the passage will feel relaxed, effortless, and completely under your command!

11. BLE MIDI & Pedalboard Setup

GAAP features universal support for wireless Bluetooth Low Energy (BLE) MIDI controllers (such as the iRig BlueBoard, Boss, and custom DIY ESP32 / nRF52840 foot controllers). Unlike rigid guitar apps that limit your hardware options, GAAP adapts to virtually any commercial or custom pedalboard on the market.

• Interactive MIDI Learning Wizard: Tap the Bluetooth icon in the toolbar. The smart pairing wizard detects incoming MIDI Control Change (CC) or Program Change (PC) messages as you tap buttons or sweep pedals on your physical controller, automatically mapping your hardware signatures to GAAP's logical control slots.
• Automated Min & Max Expression Calibration: GAAP is not limited to just two expression pedals—the app's calibration architecture is dynamic and expandable. Many commercial MIDI controllers on the market only include one or two expression jacks, but GAAP can calibrate any number of expression pedals your hardware transmits! As you sweep your pedal from heel to toe, the wizard automatically learns the exact mechanical Min and Max potentiometer range (0 to 127 or custom ranges), ensuring a smooth, full-sweep taper with zero dead zones.
• Flexible In-App Action Allocation: Once calibrated, you have complete creative freedom inside the app to assign any physical footswitch or expression pedal to any target parameter:
  • Footswitches: Assign buttons to Tuner Toggle, Tuner Mute, Looper Record/Overdub/Play/Clear, Drum Song Play/Stop, or toggling individual distortion, modulation, and delay pedals.
  • Expression Pedals: Assign any expression pedal to Wah sweeps, Pitch Shifter octaves, Delay feedback, Output Volume swells, or Reverb wet mix hands-free in real time!

12. FAQ, Troubleshooting & Billing

1. I hear audio feedback or howling!

Feedback occurs when the phone's microphone picks up sound from its own speakers. GAAP automatically engages the Feedback Shield to mute the guitar on internal speakers. Connect headphones or a dedicated USB audio interface to play feedback-free.

2. There is a delay (latency) between plucking a string and hearing the sound.

Ensure you are using a dedicated USB-C DAC/ADC audio interface or adapter. Avoid Bluetooth headphones for live playing, as the Bluetooth protocol adds 150–250ms of wireless latency. Check the Latency Pill at the top of the screen and set your profile to Ultra Low or Extreme.

3. How do I audition locked boutique pedals and amplifiers?

GAAP offers a 15-day free trial with full access to all features. After the trial, Pro subscribers unlock all 54 DSP models, preamps, and cabinets permanently with zero ads. Free users can audition any locked boutique model for a full 60-minute session simply by watching a short rewarded video ad!

4. What should I do if the audio stops when unplugging a USB interface?

GAAP features Smart Auto-Reconnect: the moment you plug your USB interface back in, GAAP automatically dismisses the disconnect alert and opens the device selection dialog for you to resume with one tap. If using a USB-C hub that fails to report device removal, simply unplug the entire hub from the phone and re-insert it.

Contact Technical Support

If you need assistance, wish to report a bug, or have billing inquiries, please reach out directly:

Email: victorhantelmann@gmail.com

Refund & Billing Policy

All subscription management and transactions are processed securely through the Google Play Store.

• Automatic Refunds (Within 48 Hours): You can request an automated refund directly through Google Play within 48 hours of purchase. Google Play Refund Instructions.
• Developer Refunds (After 48 Hours): For technical issues beyond the 48-hour window, email support with your Google Play Order ID (e.g. GPA.1234-5678-9012-34567) so we can assist you.
• Canceling Subscriptions: Uninstalling the app does not automatically cancel a subscription. Manage active plans via Google Play > Profile > Payments & subscriptions.