Communicating with the Play Electric

Auto-generated from param-defs.js — only verified, user-facing parameters are listed. For Play Acoustic, see the Play Acoustic reference.

Introduction

The TC Helicon Play Electric is a vocal and guitar effects processor that connects to a computer via USB. While it appears as a standard USB MIDI device, it does not respond to conventional MIDI messages like Control Change (CC) or Program Change (PC). Instead, all device control happens through SysEx (System Exclusive) messages — a part of the MIDI specification designed for manufacturer-specific communication.

Standard MIDI vs SysEx

Standard MIDI messages are short (1–3 bytes) and well-defined: Note On, Note Off, Control Change, Program Change. Most MIDI devices respond to these — for example, sending a Program Change to a guitar pedal typically switches presets. The Play Electric sends these messages (CC#28 for HIT, CC#32 + PC for preset changes, CC#102–107 for footswitches) but ignores them when received.

SysEx messages are variable-length, manufacturer-specific data packets that can carry anything — preset data, configuration, firmware updates. They start with F0 (SysEx start) and end with F7 (SysEx end), with all data bytes between limited to 7-bit values (0x00–0x7F). This means regular 8-bit data must be encoded into 7-bit format.

How the Play Electric Communicates

All messages to and from the device use the TC Helicon SysEx header:

F0 00 01 38 00 71 [command] [data...] F7
│  │        │  │
│  │        │  └─ Play Electric device ID (0x71)
│  │        └──── Device group (0x00)
│  └───────────── Manufacturer ID (TC Helicon = 00 01 38)
└────────────────  SysEx start

What the Device Sends (outgoing standard MIDI)

• Program Change + Bank Select (CC#32) — when you switch presets on the device
• CC#28 — when HIT is toggled on or off
• CC#102–107 — when footswitches are pressed (requires Switch-3 or Switch-6 pedal configured to send MIDI)

What the Device Accepts (incoming SysEx only)

• Preset loading — the full preset (header + 4 data packets) must be transmitted. There is no "switch to preset N" command.
• Global settings — read and write the device's setup data (HIT state, guitar effects, pitch correction, looper input, etc.) via a read-modify-write cycle.

This is the same protocol that TC Helicon's VoiceSupport 2 application uses. Everything documented here was reverse-engineered by capturing and comparing data packets between VoiceSupport and the device.

Setup Parameter Map (Global Settings)

Global setup is stored in 7 packets of 112 bytes each (0x13 command). Each parameter has a logical index s<n> used by the editor; the underlying byte positions are handled by tch-format.js.

Read: BeginSync → RequestSetup (0x15 00) → receive 7 packets → EndSync

Write: BeginSync → RequestSetup → receive 7 packets → send 7 modified packets (30ms apart) → ACK → EndSync. Read and write must be in the same sync session.

Checksum: (sum of raw bytes 10–109) % 128, stored at raw byte 110.

SysEx Commands

All messages use header: F0 00 01 38 00 71 [command] [data] F7

Preset Parameter Map

Each preset consists of 4 data packets (0x21), each containing 25 parameters encoded as 4-byte 28-bit signed integers. Parameters are indexed 0–99 across the 4 packets.

Encoding: Each parameter uses 4 bytes in 7-bit MIDI format (28-bit signed). val = ((b0 & 0x7F) << 21) | ((b1 & 0x7F) << 14) | ((b2 & 0x7F) << 7) | (b3 & 0x7F). If val ≥ 0x08000000, subtract 0x10000000 for negative values.

Packet structure: F0 00 01 38 00 71 21 [chunk#] [100 bytes data] [checksum] F7 = 110 bytes total.

Header packet: F0 00 01 38 00 71 20 [bank] [num] 01 0x03 [16-byte name] [tags] [meta] 01 F7. Byte 10 (0x03) is the preset format version — must match the device's own value or the write is silently dropped.

Packet 0 (Params 0–24)

Packet 1 (Params 25–49)

Packet 2 (Params 50–74)

Important Notes

• Header version byte — byte 10 of the 0x20 preset header is 0x03 on Play Electric (vs 0x0C on Play Acoustic). Sending the wrong value causes the device to silently drop the entire preset write — the user-facing error reads "PRESET REJECTED: VERSION".
• 4 data packets per preset (not 5) — Play Electric responds to 0x45 with 1× 0x20 header + 4× 0x21 data packets, where Play Acoustic returns 5. The same difference applies when writing presets back. Mis-counting here drops every other preset on receive and trips silent rejection on send.
• No MIDI CC input — the device only sends MIDI, never receives it.
• No preset switch command — full preset data must be sent each time.
• Effect state on preset load — when a preset loads, it sets the effect block enables in the global setup. These can be overridden by writing to the setup after the preset loads.
• Preset addressing — Bank 0: presets 1–127 (slots 1–127). Bank 1: presets 0–127 (slots 128–255). Full preset = bank × 128 + in-bank number.
• Verified mappings only — this page only lists parameters where the byte-to-meaning mapping has been verified on the device. Unmapped or speculative bytes (still tracked internally for round-trip integrity) are intentionally omitted.