Support & FAQ

Biquadia Audio DSP Lab — App Store ID 6789775886 • View on App Store

Why does the engine show -10875 or fail to start?

CoreAudio route was revoked (phone call, AirPods disconnect, backgrounding). Biquadia auto-recovers: it stops the engine, releases the route, and restarts after you re-plug or the interruption ends. If it persists, tap Refresh I/O devices in the Session sheet, or switch I/O mode to Media Playback (no mic permission needed) then back to Full Duplex.

Microphone permission and offline use?

Live labs need mic permission. Grant when prompted. The app is 100% offline — no audio leaves device. If denied, use Oscillator or bundled test clips as signal source; those work without mic permission. Enable in Settings → Privacy → Microphone → Biquadia.

What's the difference between free and Pro?

Free: full DSP Lab (filter, graphic EQ, oscilloscope, FFT) and Analysis Lab (centroid, flux, pitch, formants, MFCC, spectrogram). Pro (Monthly $4.99 with 7-day trial, Lifetime $79.99) unlocks: N-mic array beamformer (SRP-PHAT) + dual-binaural HATS, speaker diarization, target-speaker extraction, CoreML voice isolator (ANE), unlimited EQ bands, all filter families (Butterworth/LR/Chebyshev/custom 8x cascade), measurement CSV export, and binaural room IR preview.

How do screenshots show Pro features?

For App Store review we capture on iPhone 17 Pro Max (1320×2868, 6.9") and iPad Pro 13" (2064×2752) simulators with -uiTestScreenshots mock flag that seeds a 440Hz sine generator, so FFT and spectrogram are active and colorful without a microphone. Paywall screenshot is captured in free-tier mode (-uiTestScreenshotsPro=0) to show upgrade path.

I see the session bar differently on my phone vs your screenshots

iOS 26 uses tabViewBottomAccessory — a system glass capsule hosting the session bar above the tab pill. For XCUITest, Apple re-hosts that accessory content for Liquid Glass morph, breaking hit-testing, so we force a floating glass card (-uiTestForceFloatingSessionBar) for automation. For marketing screenshots we now use native accessory (no forced flag) so it matches real devices. Both have same coral/charcoal play button (charcoal→coral gradient) and 56pt height after the fix.

How to restore Pro / manage subscription?

Settings → Biquadia Pro → if Pro, tap Manage; if not, Upgrade to Pro → Restore Purchases. Or App Store → Apple ID → Subscriptions → Biquadia. Lifetime is non-consumable, tied to Apple ID, restore anytime. Monthly renews until canceled 24h before period end.

Multi-mic arrays (UMC1820 etc)?

Use a class-compliant USB-C interface. In Session → Input device, pick Auto or the specific interface. For >2 channels, set Input routing L/R to choose which physical channels feed DSP. For N-mic beamforming, enable Array Beamforming, set geometry (linear/circular), and pick channel map. I/O mixer meters show per-channel peaks.