GP200 Studio: Guide

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GP200 Studio guide

Everything GP200 Studio can do with a Valeton GP-200, in thirteen sections. GP200 Studio is a free, open-source browser editor and multi-layer loop station for the pedal , no install, no account and no backend, with your presets never leaving your machine.

If you are starting from nothing, read the overview, then connecting your GP-200. If you came here for the looper the pedal doesn't have, go straight to the loop station.

All sections

  1. 01What GP200 Studio doesWhat the app is, what it needs, and what it can do without a pedal plugged in.
  2. 02The pedalboard editorYour signal chain as physical pedals, with cables, a chain strip and stage lighting.
  3. 03Changing & managing pedalsBypass, swap, edit and reorder the effect blocks in the chain.
  4. 04The control deckPatch volume, pan, tempo, live treadle readouts, meters and the session top bar.
  5. 05Patch settings: FX loop, expression & footswitchesThe FX loop, expression pedal mapping and the eight CTRL footswitch assignments.
  6. 06Bulk apply: one patch’s settings across manyStamp one patch’s footswitch layout and volume onto a bank range, or all 256 slots.
  7. 07The loop stationUnlimited phase-locked layers over USB audio, driven from your own footswitches.
  8. 08DrumsA browser drum machine that needs no pedal, plus a remote for the GP-200’s own drums.
  9. 09MIDI remote & device stateA virtual front panel over MIDI CC, and a readout of what the unit reported.
  10. 10Managing patchesAll 256 slots in one searchable list, with per-slot actions and a full ZIP backup.
  11. 11Connecting your GP-200The USB handshake, the firmware check, and how live two-way sync behaves.
  12. 12Importing & exporting .prst filesNative .prst import and export, the same files the official editor writes.
  13. 13Requirements, browser support & privacyWhat it needs, what works offline, and what data never leaves your machine.

Frequently asked questions

Is GP200 Studio free?
Yes. It is free and open source under the GPL-3.0 licence. There is no account, no install and no backend — the code is on GitHub.
Do I need a GP-200 plugged in to use it?
No. Without a device you can still build and edit patches and import or export .prst files. Live sync and saving to the unit need a connected GP-200.
Can GP200 Studio record loops?
Yes. It records the GP-200’s USB audio as a multi-layer loop station with unlimited phase-locked takes, which the pedal’s own single-track looper cannot do.
Can I control the looper without touching the laptop?
Yes. Click the action you want, stomp any GP-200 footswitch, and it is bound. Takeover mode stops that switch changing your sound while the loop station is open.
Can I back up all my GP-200 patches?
Yes. The patch manager bulk-exports the selected bank, or all 256 patches, to a single .zip file. Do this before running Bulk Apply.
Why does connecting time out in one browser but work in another?
Because on Windows only one program at a time can own a USB-MIDI port, and a browser claims every port on the machine as soon as any page asks for MIDI, then holds them for as long as its process lives. A second browser with GP200 Studio open — or Valeton's editor, or a DAW — takes the pedal away from the one you are looking at. It reads as "Response timeout" rather than "not found", because listing ports does not open them, so the GP-200 is found and simply never answers. Close the other browser completely (Chrome can outlive its last window: check the system tray and turn off "Continue running background apps" in chrome://settings/system), quit the official editor and any DAW, then replug the pedal. If nothing else is running, compare the #use-winrt-midi-api flag between the two browsers — that MIDI backend is known to hang on the System Exclusive messages this app uses — set the failing one to match, and relaunch it.
Which browsers work with the Valeton GP-200?
Chrome or Edge on any desktop OS, and Chrome on Android. Firefox and Safari do not implement Web MIDI, so they can edit and export files but cannot talk to the pedal.
Does it work on Linux?
Yes — anywhere Chrome or Edge runs, including Linux, which the official Valeton editor does not support at all.
Why can't Chrome see my GP-200 on Linux?
Two causes look identical from the browser, and in both the CONNECT message lists only "Midi Through Port-0". Either your browser is a Flatpak or Snap build, which gets /dev/snd but no /run/udev and so drops every USB device, or the ALSA sequencer bridge is not loaded. Fix the first with "flatpak override --user --filesystem=/run/udev:ro <app-id>" and a full browser restart; fix the second with "sudo modprobe snd-seq-midi".
Why does my Flatpak or Snap browser not see any USB MIDI device?
Chromium binds ALSA cards to sequencer clients through udev, and a sandboxed browser is given the /dev/snd device nodes but not /run/udev. Every card-backed port is dropped and only card-less ones like Midi Through survive. Run "flatpak override --user --filesystem=/run/udev:ro com.brave.Browser" with your own app id, then quit the browser completely and reopen it — closing the window is not enough. A natively installed Chrome or Chromium needs none of this.
What preset file format does GP200 Studio use?
Native .prst files, byte-for-byte the same format the official Valeton editor reads and writes, so presets move between the two freely.
Do my presets get uploaded anywhere?
No. Everything runs inside the browser tab — there is no account and no server storing your patches. Only anonymous feature-usage analytics are recorded, and Global Privacy Control disables even those.