Bastl Instruments Basil Delay Module

Introduction

The Basil is a compact, yet flexible, digital stereo delay module built on the Bastl Pizza platform. It offers clean delay, as well as lo-fi flavors, and its Space section opens the doors for exploration far beyond simple delay territory. The Basil delay buffer modulates well, allowing recreation of classic time-based effects like chorus, flanger, vibrato, pitch shifter, reverb, and stereo widener. It is ideal for clean effects, ambient washes, glitchy sound design, or distorted drones. With its V/Oct input, fine delay tuning, and filter in the feedback path, it can also be used as part of a Karplus-Strong synthesis voice. The feedback amount is compensated with the shortest delay times to maintain constant decay characteristics when changing pitch.

The delay time features stereo spread and fine-tune components, and can be synchronized to the clock via the Sync jack. The feedback knob has two sides: simple feedback and ping pong mode, where the Left and Right channels cross-feedback.

The Space section offers three distinct flavors: BLUR, FILTER, and TAPS. The Blur function diffuses the delay, either directly or in the feedback path, moving the Basil delay towards experimental reverb machines. The feedback Filter offers low-pass and high-pass modes to adjust the sound's brightness. Taps are multi-taps with odd or even spacing, adding density to delays and reverbs.

The assignable CTRL knob and CV allow modulation of parameters like time, stereo, fine, dry/wet, feedback, speed, freeze, lo-fi, blur, filter, and taps, tailoring the Basil delay to specific uses.

The Speed section allows for longer delay times by running the buffer at half speed or in an extended range at quarter and eighth speeds, creating octave jumps and ensuring delays remain in tune. At lower speeds, a low-pass anti-aliasing filter is engaged to remove high frequencies. This filter can be bypassed with the LO-FI setting for a more pronounced downsampled sound.

The Freeze function treats the delay buffer as a read-only sample loop that can be layered with the incoming signal, allowing for micro-looping or ambient washes. It can be synced and modified with other parameters.

Key Features

• Flexible STEREO delay buffer
• Stereo inputs (Left normalized to Right) and outputs
• V/OCT DELAY input suitable for Karplus Strong synthesis
• STEREO spread
• FINE tune of delay time (for tonal applications)
• SYNC input for synchronized delays
• HALF SPEED with an extended range of quarter and eighth speeds, suitable for octave jumps
• Max sample rate: 41.66 kHz, 16-bit
• Max delay time in stereo: 0.5 s
• Max delay time in mono (via ping-pong): 1 s
• Max delay time at half speed in stereo: 1 s (2 s at quarter and 4 s at eighth)
• LO-FI setting for turning off the anti-aliasing filter for lower sample-rates
• DRY/WET mix with a constant power curve
• FEEDBACK knob and CV with normal (right) and ping pong (left) modes
• FREEZE function to act as micro looper or for ambient washes
• SPACE section to add more dimension (BLUR, FILTER, multi-TAPS)
• Assignable CTRL knob and CV (time, stereo, fine, dry/wet, feedback, speed, freeze, lo-fi, blur, filter, taps)
• Firmware updates via micro USB
• Interchangeable HW with the Pizza Oscillator (just a different panel)

Technical Details

• 8 HP
• PTC fuse and diode protected 10 pin power connector
• 24 mm deep
• Current consumption: +12 V: 90 mA; -12 V: 20 mA

Architecture

The signal path involves several stages. An INPUT signal first passes through a COMPRESSOR/OVERDRIVE. It then splits into DELAY TAPS and a DELAY BUFFER. The output of the buffer is fed back into itself and also processed through a FILTER and BLUR stages before reaching the DRY/WET mix. A second BLUR stage follows the FILTER. The feedback path also incorporates BLUR and FILTER elements. The module supports stereo operation, with the LEFT input normalized to the RIGHT if only one input is connected. The architecture also supports ping-pong delay routing where feedback from one channel crosses over to the other.

Controls and Connections

Main Controls

• DELAY Knob: Controls TIME, STEREO spread, and FINE adjustment.
• DELAY Button: Cycles through TIME and STEREO spread modes with a short press. A long press accesses the FINE delay adjustment.
• DRY/WET Fader: Crossfades between the clean input signal (DRY) and the fully affected delayed signal (WET).

SPEED Section

• SPEED Button: Toggles between two sample rates: full (no light) and HALF.
• RANGE Mode: Accessed by holding the SPEED button for 2 seconds, it toggles between quarter and eighth sample rates for longer delays.

FEEDBACK Section

• FEEDBACK Knob: Feeds a portion of the delayed signal back into the input, creating echoes or drones. Includes compressor and overdrive in the feedback path.

FREEZE Section

• FREEZE Button: Activates the delay buffer as a read-only sample loop.

LO-FI Setting

• Bypasses the anti-aliasing filter for lower sample rates, creating a more pronounced lo-fi character. Activated by holding the FREEZE button for over 2 seconds.

SPACE Section

• SPACE Button: Cycles through BLUR, FILTER, and TAPS flavors.
• SPACE Fader: Adjusts the intensity of the selected SPACE flavor.
• BLUR: Provides signal diffusion for reverb-like effects, with diffusion occurring before or within the feedback path.
• FILTER: Controls the tone darkness/brightness of delays, reverbs, and drones with low-pass (left) and high-pass (right) modes.
• TAPS: Adds density by mixing in signals from shorter delay times (multi-tap delay), with options for odd/even division.
• Hyper-SPACE Mode: Hold SPEED and FREEZE buttons at startup to activate all SPACE parameters simultaneously.

Assignable CTRL

• CTRL Knob & CV Input: An assignable control that can be used as a static control or attenuverter. Can modulate various parameters.
• ASSIGNMENT Mode: Enter by holding the SPACE button for a few seconds to select a destination for the CTRL knob.

Inputs & Outputs

• SYNC Input: Synchronizes delay times with an analog clock.
• V/OCT DELAY Input: Accepts control voltage for pitch-based delay time modulation, following the volts-per-octave standard.
• L IN / R IN: Audio inputs.
• L OUT / R OUT: Audio outputs.

V/OCT Calibration Mode

The module features V/OCT calibration to ensure accurate pitch tracking.

Entering Calibration Mode

• Hold the SPACE and DELAY buttons simultaneously. All LEDs will illuminate.
• Press the SPACE button to choose between quantized (stepped animation) or unquantized (smooth fading) V/OCT input.
• Exit calibration mode by holding SPACE and DELAY buttons together.

Automatic V/OCT Calibration

1. Press the DELAY button to start.
2. Connect the R OUT output to the DELAY V/OCT input.
3. Wait for all LEDs to turn ON, then disconnect the cable.
4. The LEDs will animate pointing down towards the V/OCT jack, indicating successful calibration.

External V/OCT Calibration

1. Press the FREEZE button to start.
2. Plug a cable from your V/OCT source to the V/OCT input.
3. When LO-FI is blinking, apply 0 V (C note in lowest octave) from your V/OCT source.
4. Press the FREEZE/LO-FI button to learn the 0 V value.
5. When FREEZE starts blinking, apply 2 V (a note two octaves higher) from your V/OCT source.
6. Press the FREEZE/LO-FI button to learn the 2 V value. The module will return to V/OCT CALIBRATION MODE.

Firmware Update

1. Disconnect the Basil Pizza module from your rack.
2. Connect a micro USB cable from the module to your computer.
3. Hold the DELAY button while plugging the USB into your computer.
4. The 'Pizza' will appear as an external disk on your computer.
5. Copy the firmware file (e.g., pizza_basil_*version*.uf2) to this drive.
6. Wait for the module to update and boot to normal operation.
7. Disconnect the USB cable and reinstall the module in your rack.

The firmware version is indicated by a static LED light at startup (e.g., the RANGE light is ON for the first release firmware).

Boot Settings

• Firmware Update Mode: Hold DELAY at powerup.
• Hyper-SPACE Mode: Hold SPEED and FREEZE buttons at powerup.
• Reset User Settings: Hold SPACE at powerup (resets FINE delay settings, CTRL destinations).
• Factory Reset: Hold SPACE and FREEZE at powerup (resets user settings and calibration).
• Factory Test Mode: Hold SPACE and SPEED at powerup.

Patch Tips

Time-Based Effects

Many sound effects are based on manipulating the delay buffer. The Basil allows transitions between effect categories with simple gestures.

Comb Filter

• TIME setting in the upper third.
• DRY/WET center to right.
• FEEDBACK between 2 and 4 o'clock.
• Full SPEED.
• No SPACE, FREEZE, or SYNC.
• Tweak TIME and add FEEDBACK for resonant comb filtering.

Flanger

• TIME setting in the upper third.
• DRY/WET in the middle.
• FEEDBACK between 2 and 4 o'clock.
• Full SPEED.
• No SPACE, FREEZE, or SYNC.
• Assign CTRL to modulate FINE delay time with a slow sine/triangle LFO.

Stereo Chorus / Stereo Vibrato

• TIME setting in the upper third.
• DRY/WET on max (vibrato) or middle (chorus).
• Little to no FEEDBACK.
• Full SPEED.
• No SPACE, FREEZE, or SYNC.
• Assign CTRL to modulate STEREO time spread with a slow sine/triangle LFO. DRY/WET fully right yields vibrato; mixing DRY creates chorus; adding FEEDBACK creates a stereo flanger.

Pitch Shifter

• TIME setting in the upper third.
• DRY/WET on max.
• No FEEDBACK.
• Full SPEED.
• No SPACE, FREEZE, or SYNC.
• Use a ramp LFO to modulate FINE delay time via CTRL. Turning CTRL right pitches up, left pitches down, leading to reverse effects.

Tempo-Synced Rephraser / Repitcher / Reverser

• TIME setting in the middle.
• DRY/WET on max.
• No FEEDBACK.
• Half SPEED for more range.
• No SPACE, FREEZE, or SYNC.
• Similar to Pitch Shifter but uses tempo-synced LFO to modulate TIME via CTRL. Right on CTRL pitches up, left pitches down, leading to reverse effects.

Stereo Widener

• TIME setting in the upper third.
• STEREO spread in the upper half.
• DRY/WET for width.
• No FEEDBACK.
• Full SPEED.
• No SPACE, FREEZE, or SYNC.
• Set TIME in the upper third, use DELAY knob for STEREO spread. DRY/WET controls width. Set SPACE to BLUR and move fader left for abstract width.

Reverb

• TIME setting around 1 o'clock.
• STEREO spread to liking.
• FEEDBACK in the upper third.
• Full SPEED.
• SPACE set to BLUR.
• CTRL set to FILTER (or TAPS).
• No FREEZE, no SYNC.
• For more control, use Hyper-SPACE mode. Modulate FINE delay time for modulated reverb. Use CTRL on DRY/WET for gated reverb.

Wow & Flutter Delay

• TIME setting according to desired delay time.
• FEEDBACK around 3 o'clock.
• Full SPEED.
• CTRL assigned to FINE delay time.
• No SPACE, FREEZE, or SYNC.
• Modulate CTRL (assigned to FINE delay time) with smooth random CV for tape delay wow & flutter effects.

External Feedback Delay

• Set TIME as desired.
• FEEDBACK on the left side (ping pong).
• Full SPEED.
• No SPACE, FREEZE, or SYNC.
• Affect feedback signal externally by splitting L OUT to another module (e.g., downsampler, filter, pitch shifter) and returning to R IN. Use FEEDBACK knob left for ping-pong mode.

Double-Length Mono Delay

• TIME setting on longest.
• FEEDBACK on the left side (ping pong).
• Full SPEED.
• No SPACE, FREEZE, or SYNC.
• Utilize ping pong mode with Left input and Left output to effectively double the delay buffer. FEEDBACK knob right of 12 o'clock yields half-time delay. HALF speed or extended RANGE features can achieve longer times with potential audio quality loss.

Octave Lo-Fi Looper

• TIME on lower settings.
• FREEZE activated.
• Long RANGE SPEED.
• No SPACE.
• SYNC to a clock.
• CTRL assigned to FILTER.
• Create lo-fi loops up to 2 bars long. Transpose loops up/down an octave by pressing the SPEED button. Engage SPACE BLUR or FILTER to modify loops.

Minecraft Reverb

• TIME setting on full CW.
• FREEZE activated.
• Long RANGE SPEED + HALF SPEED.
• SPACE set to BLUR.
• No FREEZE (this seems to be a typo, likely meant 'no SYNC' or similar, but transcribing as is).
• LO-FI activated.
• CTRL assigned to FILTER.
• For crunchy, lush lo-fi reverb tails, set SPEED to lowest (long RANGE + HALF speed) and TIME to shortest (full CW) with LO-FI active. Add BLUR, FEEDBACK, and CTRL assigned to FILTER for control.

Stereo Karplus-Strong Voice

• TIME setting in the upper third.
• FEEDBACK on the right (sets Decay).
• Full SPEED.
• SPACE set to FILTER.
• No FREEZE, no SYNC.
• Create physical modeling synth sound by starting with a noise burst into a VCA controlled by an envelope, optionally through a resonant filter. Set FEEDBACK to higher resonant settings and TIME to the upper third. Use FINE control to tune root note and run a pitch sequence to DELAY V/OCT input. FEEDBACK knob controls decay, FILTER controls decay timbral characteristics. CTRL knob assigned to TAPS controls resonant harmonics.

Sound Design Feedback

• TIME setting all around.
• STEREO on fully right.
• FEEDBACK on max CCW or CW.
• Full SPEED.
• SPACE set to FILTER.
• CTRL assigned to TAPS.
• No FREEZE, no SYNC.
• Create a feedback loop by connecting L OUT to L IN and DELAY V/OCT input. Listen in stereo using R OUT. Set FEEDBACK knob fully left or right. Use CTRL for TAPS, and index finger to tweak delay time while moving SPACE slider to FILTER. Experiment for chaotic sounds.

Credits

Development Team: Florian Helling & Martin Klecl

Supervised by: Václav Peloušek

Bootloader: Lennart Schierling (Binary Labs)

Main Tester: Juha Kivekäs

Beta Testers: David Žáček, Milan Říha, John Dinger, Václav Mach, Peter Edwards, Oliver Torr, Patrik Veltruský, Niels Aras, Leoš Hort, Leo Hivert, Martin Klecl

Management: John Dinger

Graphic design: Anymade Studio

The idea was realized thanks to everyone at Bastl Instruments and the support of fans.

More Information

For more info and video tutorials, visit: www.bastl-instruments.com