Spindle

One-Wire Polyphony for Player Stacks

Reason’s Spider Audio Merger & Splitter and Spider CV Merger & Splitter have handled audio and control voltage routing for over two decades, but Note Players have always been strictly linear: locked into a single top-to-bottom stack above one instrument. Spindle is the missing third Spider.

In a single 1U Player slot, Spindle gives you one-wire connectivity between Player stacks (SilkLink) with unlimited polyphony and sample-accurate synchronization, plus bidirectional translation to and from standard analog Note + Gate CV. Split an upper Player chain across multiple instruments (and downstream Player branches) in lockstep, merge up to 8 Player stacks into one note stream, drive in-rack synths and external hardware gear (via Reason’s built-in MIDI Out device) at the exact same time, or translate between Players and analog CV.

Spindle is $0 (Free Forever), built with the same care and attention to detail as my paid Rack Extensions.

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In the Rack: Five Everyday Routing Workflows

1. Splitting Upper Players Across Multiple Instruments in Lockstep

Drop a Spindle below a generative note source, chord generator, or sequencer stack, and run a single rear cable from OUT 1 (SILK) to IN 1 on a second Spindle stacked above another instrument. With STACK set to SYNC (the default), every destination stack moves in sample-level lockstep, meaning no delays and no comb filtering when layering synths.

2. Driving In-Rack Synths and External Gear Simultaneously

If you’ve ever wanted a single Player stack to play an in-rack instrument and an external hardware synth at the same time without duplicating tracks or Player chains, patch a SILK output from your synth stack’s Spindle over to a second Spindle stacked above Reason’s built-in MIDI Out device. Both instruments receive the exact same note stream in unison.

3. Merging Multiple Player Stacks Into One Instrument

Patch up to 8 independent Player chains (or any mix of SilkLink cables and analog Note + Gate CV sequencers) into IN 1 through IN 8 above a single instrument. You can combine separate bass, chord, and melodic generators into one synth or piano, using the front-panel 1 through 8 buttons to mute and unmute incoming branches on the fly without leaving any hanging notes behind.

4. Branching One Harmonic Source Into Separate Downstream Player Chains

Because a receiving Spindle sits inside a standard Player stack, each split branch can run its own downstream Players before hitting its instrument. Place one Spindle below a chord generator (like Scales & Chords or Quad Note Generator) to play raw chords on a pad synth below it, while sending a SILK cable to a second Spindle placed above an Arpeggiator on a lead synth and a third Spindle above a Note Echo on a pluck. Every branch follows the same master chord progression while playing its own part.

5. Translating Between Player Stacks and Modular CV (SilkLink <-> CV)

Spindle’s inputs auto-detect analog CV and its outputs can be set individually to SILK, CV LAST, or CV POLY, so it also functions as a two-way SilkLink <-> CV translator. Patch a Matrix or Pulsar Note + Gate CV pair into IN 1/2 to feed downstream Note Players, or convert a Player stack into analog 1V/Oct Pitch and velocity-scaled Gate CV: either in monophonic last-note priority (CV LAST for mono CV synths and filter key-tracking) or split polyphony (CV POLY, distributing up to four chord voices across the four Note/Gate pairs for Oberheim Four Voice-style mono synth polychaining or multi-oscillator Complex-1 patches).

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Tactile Control: Front & Rear Panel

8-to-1 Auto-Detect Input Merger & 3-State STACK Switch

On the left side of the panel, Spindle provides 8 Auto-Detect Inputs (IN 1 through IN 8) alongside a click-to-cycle 3-state STACK switch:

• Auto-Detect Inputs: Each input automatically detects whether it’s connected to a one-wire polyphonic SilkLink cable (indicated in cyan) or a standard analog Note + Gate CV pair (indicated in amber) and switches modes on its own. Front-panel 1 through 8 buttons let you mute or enable any input branch cleanly.
• 3-State STACK (SYNC / THRU / MUTE): Click the STACK switch on either the front or rear panel (or Shift-click to step backward) to choose how notes flow vertically down the local Player stack:
  • SYNC (Default): Holds upstream Player notes in lockstep with active rear SILK outputs so the local instrument and all remote SilkLink destinations trigger on the exact same sample.
  • THRU: Passes upstream Player notes straight down to the local instrument with zero buffering while also sending them to the rear outputs.
  • MUTE: Mutes vertical flow to the local instrument below while still routing upstream Player notes out the rear jacks.

1-to-8 Dual-Mode Output Splitter

On the right side, 4 Output Pairs (OUT 1/2 through OUT 7/8) click-cycle independently across four modes on either the front or rear panel:

• SILK (One-Wire Polyphonic Output): Broadcasts the merged SilkLink stream on both jacks of the pair (giving up to 8 independent SilkLink outputs across the 4 pairs), carrying unlimited polyphony, velocity, pitch bend, aftertouch, CCs, and scale metadata over a single cable per destination.
• CV POLY (Split Polyphonic CV): Pools any output pairs set to POLY into a 1-to-4 voice polyphonic 1V/Oct Note CV (odd jack) + velocity-scaled Gate CV (even jack) voice allocator, including live pitch-bend modulation.
• CV LAST (Monophonic Last-Note CV): Outputs monophonic last-note priority 1V/Oct Note CV on the odd jack (1, 3, 5, 7) and velocity-scaled Gate CV on the even jack (2, 4, 6, 8) with held-note trilling fallback.
• OFF: Mutes the output pair.

Live Routing Scope

The center display shows which inputs (STACK and 1 through 8) and outputs (STACK and 1/2 through 7/8) are actively passing notes in real time, and sleeps at 0% idle CPU whenever notes are at rest.

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Under the Hood: The SilkLink One-Wire Protocol

Standard Reason CV cables carry a single 32-bit floating-point value updated once per 64-sample audio batch (689.06 Hz at 44.1 kHz, 750 Hz at 48 kHz). To carry full polyphony and controller data over one cable without false triggers from standard CV sources, I designed SilkLink, a sign-split multi-exponent 29-bit IEEE-754 protocol:

• Exceeds Hardware MIDI Cable Rate at 44.1 kHz: By packing multi-note chord frames (QuadNote, WideTriadNote, and independent-velocity DualNote) alongside sample-offset single notes (FrameIndex 0 to 63) across the positive floating-point exponent range (Exp 63 to 126, 29 payload bits per batch with a 1-bit hardware anti-collision toggle), SilkLink reaches 2,756 notes/sec at 44.1 kHz, 3,000 notes/sec at 48 kHz, and 6,000 notes/sec at 96 kHz (exceeding the note rate of a standard 31.25 kbps 5-pin MIDI cable even at 44.1 kHz, and scaling up with sample rate).
• Carries Anything Expressible in MIDI: Beyond the notes and velocities that Players generate, SilkLink encodes 14-bit Pitch Bend, 7-bit Control Changes (CC 0 to 127), Channel Pressure, Polyphonic Aftertouch, Bank + Program Change, Step Clock Sync, and 12-bit Scale Metadata, with automatic in-queue controller coalescing and a 256-slot NoteOff-safe buffer.
• Connect-Time Handshake & Self-Healing Note Audit: The negative half-range (-1.0 to -0.5) is reserved for a connect-time handshake ("SL" magic signature) and a bounded 18-batch active-note audit sweep before parking on a static float at rest (0 Hz steady-state motherboard traffic). Plugging a hot LFO or audio-rate CV signal into a Spindle input will never falsify the handshake or trigger stray notes, and hot-plugging a SilkLink cable while a chord is held automatically syncs the held notes and active controller state.
• Open & MIT-Licensed for Fellow RE Developers: Following the Spindle beta period (once any beta-driven protocol refinements are locked in), I will be releasing the full SilkLink specification and unencumbered MIT-licensed C++17 reference code so any developer can add one-wire polyphonic connectivity to their own Rack Extensions (whether Players, instruments, CV utilities, or effects).