The Shift Line Prism II is a stereo filter-pad pedal, released in May 2021, that packs pitch shifting, multimode filters, modulation and reverb into one box12. Delicious Audio described it as combining "elements of subtractive and additive synthesis, reverb, and frequency, time and space modulation" in a single circuit3. It is a new generation of the maker's Prism-9 complex effect pedal, built as a stereo version with two identical processing chains and a separate mix section at each stage43.
The Prism II is discontinued; Shift Line marks both the standard pedal and the Black Edition as discontinued products42.
- Current draw: 150mA at 9V DC, 100mA at 12V DC42
What the Prism II does
The incoming signal first passes through a three-channel pitch shifting section: octave down, fifth up and octave up, each channel with its own low-pass filter4. From there the signal moves through three filter channels, LPF, BPF and HPF, each with a 12dB/Oct slope and controllable resonance4. Everything is organized in two identical chains so the device works in stereo, with a separate mix section at each stage4.
The 12 patches are algorithms rather than simple presets, and each can be fine-tuned through the pedal's config file21. The Blue bank holds Synthation Flow, Shu Melody and CM116; the Red bank holds BUTTER, MS20X3 and CM122 plus a random option4.
The BASE knob sets the minimum frequency for the device's filters2. The BYPASS (DETUNE) footswitch turns the effect on and off with a single press, enters Detune Mode when held, recalls the Favorite preset with a double press, and selects the bank or bypass mode when held together with other controls4.
Tap tempo, LFOs and the config file
Tap tempo is dialed in through the right footswitch or an external link, with a choice of duration and the ability to slow down or speed up the modulation interval in multiples from 2 to 32 times3. The BEAT switch sets the subdivision: UP is 3/4 (dotted eighth note), CENTER is 1/1 (quarter note), and DOWN is 2/3 (quarter note triplet)2. The stable BPM range is 30 to 300, and the pedal is designed to be clocked in quarter notes with 0.005 to 2 seconds between control signals2.
The pedal carries several LFOs, and not all of them have knobs:
| LFO | Wave | How it is set |
|---|---|---|
| LFO MAIN | Triangle | RATE knob or TAP footswitch2 |
| LFO2 | Sine | Config file only, no physical controls2 |
| LFO3 | Saw/random | Rate linked to LFO MAIN at a ratio such as 1/2x, 3x or 4x2 |
| MOD LFO | Configured in config file | No physical controls, main purpose is soft modulation2 |
A fifth shaping stage, LFO COMMON, distorts the incoming wave into a trapezoid wave at values 1.1 to 3, or an "almost square" wave at values 4 to 10002.
Deep editing happens through the config file. The pedal's flash drive has an AFXSETUP folder containing the PRISM2.SET file, editable in any text editor, which holds the 12 programs along with global settings1. These include the BEAT switch time coefficients (#GLOBAL_TAP_UP, default dotted eighth at 0.75, and #GLOBAL_TAP_CENTER, quarter note at 1.0) and the #GLOBAL_JACK_EXT_TAP value that configures the external control jack1.
Power and connections
The Prism II takes a universal 9 to 12V power intake, which Shift Line describes as low current draw by digital device standards at 100 to 150mA: 150mA at 9V DC, 100mA at 12V DC4.
The audio jacks are all 6.3mm mono unbalanced: LEFT IN and RIGHT IN at 1MOhm input impedance (LEFT IN is the main mono input), LEFT OUT and RIGHT OUT at 100Ohm output impedance (LEFT OUT is the main mono output)2. The inputs and outputs do not support TRS connections2. The enclosure is a lightweight, compact aluminum body with the connectors on the top edge for easier pedalboard layout23.
External control: MIDI, expression and analog trigger
The EXT.TAP input is a 6.3mm jack that accepts a normally open momentary button, MIDI, or a 5V analog trigger (S-trig or V-trig) with up to a 2-second interval between two consecutive signals42. The #GLOBAL_JACK_EXT_TAP parameter in the config file selects the mode1:
- 0: passive external controller, a normally open momentary button that mirrors the TAP footswitch1
- 1: S-trigger, a short circuit analog trigger/gate1
- 10: MIDI Clock, which sets the modulation rate and makes the RATE knob and TAP footswitch inactive1
- 30: Favorite preset control, brief press to enter or exit, hold over 3 seconds to save1
For MIDI, the pedal accepts two parameters from the MIDI System Real Time protocol: Clock sets the LFO rate and Start resets the LFO4. No MIDI channel needs to be set for clock sync4. The pedal also responds to a MIDI channel set by #MIDI_CHANNEL, default 1, with accepted values 1 to 165, and MIDI connection is made through a 6.3mm Type A stereo jack4.
Firmware updates
The Prism II connects to a computer through a microUSB port on the right side of the pedal, requiring a USB 2.0 port or higher1. The update process:
- Copy the update file, p2update.bin, to the root folder of the PRISM 2 drive, without renaming it1
- Wait for both LEDs to glow blue, which means the pedal is ready for the update1
- The update takes two minutes to complete1
An interrupted firmware update can render the pedal unusable1.
Firmware 1.2, dated 2021-10-24, was installed on pedals manufactured after August 30, 2021, on hardware version 1.2.71. The product page description refers to firmware v1.24.
The Black Edition and where the Prism II came from
The Black Edition is a version of the Prism II stereo filter-pad with the same core design: 12 algorithms fine-tunable via the config file, three global modes (tap tempo, LFO reset, expression pedal simulation), and the lightweight aluminum enclosure with top-mounted jacks2. Shift Line lists it as discontinued2.
The Prism II traces back to the Prism-9: Shift-Line describes it as a new version of the Prism-9 complex effect pedal23. The Prism II was released in May 2021, and multiple changes have been made to the device's firmware since then1. Shift-Line later discontinued the pedal, and the Black Edition carries the same "THIS PRODUCT IS DISCONTINUED" notice on the maker's pages42.
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Questions
Can the Shift Line Prism II run on a battery?
No. Shift Line states the pedal cannot be battery-powered and should be run from a regulated power supply only. It accepts 9 to 12V DC through a 2.1/5.5mm center-negative barrel jack, drawing about 150mA at 9V or 100mA at 12V.
Does the Prism II accept TRS cables?
The LEFT IN and RIGHT IN inputs and the LEFT OUT and RIGHT OUT outputs are 6.3mm mono unbalanced jacks and do not support TRS connections. The EXT.TAP control input is different: MIDI connection is made through a 6.3mm Type A stereo jack.
How do you update the Prism II firmware?
Connect the pedal's microUSB port to a computer (USB 2.0 or higher), copy the update file p2update.bin to the root folder of the PRISM 2 drive without renaming it, and wait for both LEDs to glow blue, which means the pedal is ready. The update takes two minutes, and an interrupted update can render the pedal unusable.
How do you switch banks on the Prism II?
Hold the BYPASS footswitch and move the MODE switch: UP selects the Blue bank, MIDDLE the Red bank, DOWN the Magenta bank. Holding TAP instead of BYPASS while changing MODE accesses the Cyan bank. Each bank holds three patches, twelve in total.
Is the Prism II clean signal path analog?
Yes. Shift Line describes the Prism II as having a fully analog dry signal chain, so your unprocessed guitar signal stays analog while the effect processing happens in the digital domain.
What is the Prism II Black Edition?
The Black Edition is a version of the Prism II stereo filter-pad with the same core feature set: 12 algorithms fine-tunable through the config file, three global modes, and an aluminum enclosure with top-mounted jacks. Shift Line lists it as discontinued.
Sources (5)
- A+ Prism II, Shift Line, 2026
- A+ Prism II Black Edition, shift-line.com, 2026
- Shift Line Prism II Stereo Filter Pad, Delicious Audio, 2021-05-13
- A+ Prism II, Shift-Line, 2026
- A+ Prism II, shift-line.com, 2026
