# TC LINK — User Manual **Twisted Cable — TC LINK** Ableton Link timing, transport, musical structure and clock generation for VCV Rack 2. 10 HP panel; listed as **TC Link** in Rack’s module browser. Version 2.0.2 | 07-11-2026 TC LINK module panel *Panel illustration in the Default theme; display states and channel names are examples.* --- ## In this manual 1. [Overview](#overview) 2. [Getting Started](#getting-started) 3. [Themes](#themes) 4. [Transport Display](#transport-display) 5. [Musical Structure](#musical-structure) 6. [Click Section](#click-section) 7. [Outputs](#outputs) 8. [CLKD Integration](#clkd-integration) 9. [Link Status](#link-status) 10. [Multiple TC LINK Modules](#multiple-tc-link-modules) 11. [Using the audio companions](#using-the-audio-companions) 12. [Troubleshooting](#troubleshooting) 13. [Known Limits](#known-limits) --- ## Overview TC LINK is the timing core of the TC Link plugin. It joins an Ableton Link session and converts the shared tempo, phase and transport into Rack clocks, triggers, gates, visual progress and an audible click. The module provides an integrated beat, bar and phrase workflow: - Beat, bar and phrase counters - Three progress radars - Beat, bar and phrase trigger outputs - Selectable beat, bar or phrase click - Independent structural lengths TC LINK works without another Link peer. In that state it provides the same local timing functions while remaining ready for another Link application to join. --- ## Getting Started Install TC Link through VCV Library. In Rack’s **Library** menu, sign in with the VCV account that owns TC Link and install any available updates. 1. Add one **TC LINK** module to the patch. 2. Enable Link in Ableton Live or another Link-enabled application. 3. Confirm that the TC LINK peer display changes from `-- LINK` to `✓ LINK`. 4. Set the desired tempo from TC LINK or any connected Link application. 5. Patch `CLOCK`, `RUN` and `RESET` to the transport inputs of a sequencer. 6. Use the beat, bar and phrase outputs where structural triggers are needed. **L TX** and **L RX** work independently for network audio. Add TC LINK when you also need tempo controls, transport or timing outputs. All three module types share one Link participant and may sit anywhere in the patch. --- ## Themes Right-click the module and open **Theme**: - **Dark:** Default, Copper, Glacier, Moss and Amethyst. - **Light:** Medi and Brit. Choose **Use as default** to use the selected theme for newly added TC Link modules. Existing modules keep their saved choices. The active TC LINK sets the theme for all companions. Without an active core, a companion uses its saved local choice. Theme changes do not alter sound, timing or the fixed TC branding colours. --- ## Transport Display Tempo, up/down buttons, RUN, SYNC and Link phase controls *Set the session tempo and transport from the upper display. The up/down buttons beside the BPM value adjust tempo in 0.1 BPM steps.* The upper display contains the session tempo, RUN and SYNC controls, the up/down tempo buttons, the quantum phase bar and Link peer status. ### BPM The large value shows the current Link session tempo. To change tempo: - Place the mouse anywhere inside the upper TC LINK display, including over RUN, SYNC, the phase bar or the tempo buttons. - Press the keyboard **Up** or **Down** arrow to change tempo in **1 BPM** steps. - Click **▲** or **▼** immediately to the right of the BPM digits to change tempo by **0.1 BPM per click**, including the decimal digit. The two small rectangular buttons use the same theme and styling as RUN and SYNC. - Type a value in `xxx.x` format for direct entry while the mouse is inside the display. - Press **Enter** to accept an incomplete entry. - Press **Escape** to cancel. Keyboard capture ends when the mouse leaves the display. RUN and SYNC retain their transport functions; the tempo buttons change only the session tempo. The supported session range is 20.0–999.0 BPM. A local tempo change is shared with the other Link peers. ### RUN The RUN square controls TC LINK transport. - Lit: transport is running. - Unlit: transport is stopped, or a quantized start is still waiting. A start may wait for the Link quantum before playback begins. Press RUN again during that wait to cancel the pending start. When stopped, the counters and radars return to their starting positions, clock and click output stop, and `RUN` outputs 0 V. The quantum phase bar continues moving at reduced brightness so the underlying Link timing remains visible. ### SYNC SYNC enables Ableton Link Start/Stop Sync. - Lit: TC LINK sends and follows Link start/stop changes. - Unlit: tempo and phase remain linked, but transport changes are local. RUN and SYNC are saved with the Rack patch and restored by preset loading, paste and undo/redo. Both controls are also available from the module’s right-click menu under **Link transport**. A new shared session starts with RUN and SYNC disabled. Adding a fresh core to an existing audio session preserves that session’s transport and SYNC state. Loading saved module settings can restore different RUN and SYNC values. ### Quantum phase bar The four-segment bar shows position within the Link quantum. The **beats-per-bar** control sets that quantum, so changing it changes the length of the complete phase-bar cycle. Bars per phrase and phrase count do not change the Link quantum. They define TC LINK’s local musical structure above the shared beat timeline. --- ## Musical Structure Beat, bar and phrase counters, knobs and progress radars *BEAT, BAR and PHRASE each pair a length control with progress and a trigger output.* The centre display is divided into three columns. | Column | Range | Function | |--------|-------|----------| | **BEAT** | 2–16 | Beats per bar and Link quantum | | **BAR** | 1–64 | Bars per phrase | | **PHRASE** | 1–96 | Phrases in the complete structural cycle | Each column contains: - A maximum/current counter - A length control - A progress radar in the selected theme’s accent colour - A 10 V trigger output - A trigger indicator The counters start at 1. On the first audible beat, the beat display remains on beat 1. Bar and phrase transitions follow the same first-step convention. ### Structural relationships ``` BEAT count × BAR count × PHRASE count ↓ complete TC LINK structural cycle ``` **Example: a 16-bar passage.** Set BEAT to 4, BAR to 4 and PHRASE to 4. Each bar contains four beats, each phrase contains four bars, and the full cycle contains four phrases. Patch BAR to an accent or pattern-change input; use PHRASE for a change every four bars. Changing **BEAT** realigns the local structure to the selected Link quantum. Changing **BAR** or **PHRASE** changes the higher-level TC LINK structure without changing the shared Link quantum. --- ## Click Section MODE, VOL and CLICK controls *Choose the click interval, set its level and patch CLICK to your mixer.* ### MODE The three-position MODE switch selects the click interval: - **Beat** — click on every beat - **Bar** — click at the start of every bar - **Phrase** — click at the start of every phrase The first click of the selected structure is accented with the higher click. ### VOL Sets click output level from 0–100%. Route CLICK through a mixer or audio output module to hear it. VOL affects only this metronome, not the rest of your patch or the audio companions. ### CLICK Audio click output. The output stops immediately when transport stops and resumes in phase with the Link timeline. --- ## Outputs RESET, RUN and CLOCK outputs *The lower transport outputs connect TC LINK to a sequencer.* | Output | Signal | |--------|--------| | **BEAT** | 10 V, 1 ms trigger at each beat | | **BAR** | 10 V, 1 ms trigger at the first beat of each bar | | **PHRASE** | 10 V, 1 ms trigger at the first beat of each phrase | | **CLICK** | Audible click at the interval selected by MODE | | **RESET** | 10 V, 1 ms reset trigger when transport stops | | **RUN** | 10 V while running, 0 V while stopped | | **CLOCK** | Selectable 1–96 PPQN Link-synchronised clock, 10 V pulses up to 1 ms | `CLOCK`, `RESET` and `RUN` are suitable for driving sequencers that accept standard Rack clock, reset and gate levels. Clock pulses are limited to half the clock period at high rates, preserving a low interval between pulses. **Choose the resolution your sequencer expects.** PPQN means pulses per quarter note: 1 PPQN gives one pulse per beat, while 24 PPQN gives 24 pulses per beat. A mismatched setting makes a sequencer run at the wrong speed. The clock resolution submenu offers 1, 2, 4, 8, 12, 24, 48 and 96 PPQN. New instances default to 1 PPQN. Each module stores its selection in the patch; **Set as global default** applies the current selection to subsequently created instances. Unchecking **Set as global default** removes the override, so new instances return to the factory default of 1 PPQN. Existing modules retain their patch-saved resolution. --- ## CLKD Integration Place an Impromptu Modular CLKD module directly against either side of TC LINK to use the CLKD integration options in the right-click menu. Enable **Run CV input is level sensitive** in CLKD. This is required for tight transport integration with TC LINK’s persistent RUN output. ### Auto-patch CLKD When enabled, **Auto-patch CLKD** connects any empty CLKD transport inputs: | TC LINK output | CLKD input | Cable | |----------------|------------|-------| | **RESET** | Reset | Red | | **RUN** | Run | Green | | **CLOCK** | External clock | Blue | Existing input cables are not replaced. Automatically created cables remain ordinary Rack cables and can be moved or removed normally. ### Run from CLKD When **Run from CLKD** is enabled, pressing the RUN button on an adjacent CLKD also toggles TC LINK transport. Disable it when CLKD’s RUN button should not control TC LINK. **Auto-patch CLKD** and **Run from CLKD** are global preferences rather than patch settings. Changing an option affects this core and the default for newly added TC LINK modules; it does not update other existing cores. --- ## Link Status Link peer status line *The peer line counts other Link applications, not your companion modules.* The line below the quantum phase bar reports the network state. | Display | Meaning | |---------|---------| | `-- LINK - PEERS: 0` | TC LINK is active but no other Link peer is connected | | `✓ LINK - PEERS: #` | One or more external Link peers are connected | The peer count represents other Link participants visible to TC LINK. Adding L TX, L RX or disabled duplicate cores does not create additional network peers. --- ## Multiple TC LINK Modules Only one TC LINK core may be active in a patch. If another TC LINK is added while a non-bypassed core is already active: - Its panel is dimmed. - `DISABLED` is shown vertically. - All outputs remain at 0 V. - It cannot change tempo, RUN or SYNC. - Its counters, radars and click do not run. If the active core is removed or bypassed, the oldest remaining non-bypassed core takes over. If no eligible core remains, a non-bypassed audio module maintains shared audio processing. The Link connection and channel selections are retained; removing the last core does not stop network audio. Unbypassing an older core can return timing control to it. Bypassed modules cannot own shared audio processing. If all modules are bypassed, the Link connection stays enabled, but those modules do not process audio. The session closes when its last module is removed. --- ## Using the audio companions TC LINK, L TX and L RX use one shared Link and Link Audio session. A core is optional for sending and receiving audio. - **TC Link Send**, titled **L TX** on its panel, publishes Rack audio as Link Audio channels. - **TC Link Receive**, titled **L RX** on its panel, subscribes to Link Audio channels and converts them to Rack audio. - Adding more modules does not create additional Link peers. - Adding or removing a core preserves the existing audio session and channels. - TC LINK adds timing and transport controls to that session. - Companions can be placed anywhere in the patch. See the separate L TX and L RX manuals for channel assignment and display states: [L TX manual](TC-Link-Send_manual.md) and [L RX manual](TC-Link-Receive_manual.md). --- ## Troubleshooting ### A module is unavailable or reports an access problem Confirm that Rack’s **Library** menu is signed into the account that owns TC Link, then refresh the Library and install any available updates. If the problem remains, contact VCV support at support@vcvrack.com. ### No peer is shown - Confirm that Link is enabled in the other application. - Confirm that both applications have permission to use the local network. - Confirm that both devices are on the same reachable network. ### A sequencer does not follow CLOCK - Patch all three transport signals where supported: `RESET`, `RUN`, `CLOCK`. - Confirm that the destination expects the selected PPQN or configure its clock input accordingly. - Start from a stopped/reset state before checking the first beat. ### Link tempo follows but transport does not Enable **SYNC** in TC LINK and Start/Stop Sync in the other Link application. ### CLKD does not follow or control TC LINK transport - Confirm that CLKD is directly adjacent to TC LINK. - Enable **Run CV input is level sensitive** in CLKD. - Confirm that `RESET`, `RUN` and `CLOCK` are patched to the corresponding CLKD inputs. - Enable **Run from CLKD** if the CLKD RUN button should control TC LINK. ### A second TC LINK is disabled This is intentional. Only one core is active. Remove the active core to promote the oldest disabled instance. --- ## Known Limits - Network audio latency is controlled partly by the Link Audio host application and network conditions. - Dropout and underrun performance depends on network stability, audio hardware, driver configuration and buffering. - Controlled latency and dropout measurements should be made with a stable network and professional audio interface. --- ## Trademark Notice Ableton, Link and Ableton Live are trademarks of Ableton AG. TC Link is an independent Twisted Cable product and is not affiliated with or endorsed by Ableton AG.