Fletcher Audio · Tube compression
6386e
Compression with room for character.
Product artwork and actual plugin interface · macOS and Windows
Shape response and colour
The 670 timing network
Stereo · Dual · Lat-Vert
Documentation
Compression with room for character.
- Set the amount
- Threshold sets how much of the output reaches the sidechain, as on the 670. Because the detector listens to the output, compression bends gradually into limiting instead of following a fixed ratio.
- Choose the knee
- DC Threshold, a screwdriver adjustment inside the hardware, biases the sidechain tube. Low settings compress early and softly; high settings leave quiet passages alone, then compress more firmly.
- Pick a Time Constant
- Six positions, as on the 670: attack from 0.2 to 0.8 ms and release from 0.3 s to 5 s, plus two program-dependent positions that release faster after a single peak than after sustained compression.
- Turn up the Heat
- Drive the 6386 tubes up to 10 dB harder for more harmonics, with the level brought back down after them. The sidechain hears the compensated output, so the amount of compression stays about the same.
- Give another track control
- Switch the detector to External and choose a kick, vocal or other track in your DAW’s sidechain menu. The detector HPF offers Off, 40, 80, 120 and 180 Hz for either source.
- Keep the blend in reach
- Stereo shares one sidechain, Dual compresses each channel on its own, and Lat/Vert is the 670’s sum-and-difference mode. Mix blends 0–100% wet; Input Gain is the 670’s attenuator in 1 dB steps.
Your compressor, in view
Follow the gain reduction.
- Meter
- An analogue-style needle and numeric readout show gain reduction from the sidechain’s control voltage, like the 670’s meter. With two channels it follows the one with more reduction.
- Graph
- The circuit’s settled input/output curve for your settings, with the live signal on it, beside six seconds of input level, output level and gain reduction.
- Familiar gestures
- Drag to adjust, hold Shift for finer control, or type a value. Double-click a dial to reset it. Your DAW saves the parameters and Meter/Graph view with the project.
About the 6386 model
The “e” stands for emulation. 6386e 2.0 models the Fairchild 670 from its 1959 manual and schematic: the input attenuator and transformer, four 6386 sections per side in push-pull, the output transformer, the feedback sidechain and its six-position timing network. The supplies sag, ripple and drift, which moves the circuit’s behaviour without adding hum or hiss. Harmonics come from the tube law (fitted to GE’s published curves) and the transformer cores, not a waveshaper; the model is checked against published measurements of a real 670, not a unit on our bench. The guide includes four circuit sheets and the model’s limits.
Compatibility
System requirements
- macOS 11 or later
- Universal Apple Silicon and Intel build.Audio Unit and VST3 · Mono or stereo audio
- Windows 10 / 11
- 64-bit x64.VST3 · Mono or stereo audio
- Activation
- An AudioNode account and internet access for initial activation and successful validation at least every 30 days.
Your DAW may require a newer operating system. AAX / Pro Tools and VST2 are not included.
Choose your format
| DAW | Mac | Windows |
|---|---|---|
| Logic Pro | Audio Unit | — |
| Ableton Live | Audio Unit or VST3 | VST3 |
| FL Studio | Audio Unit or VST3 | VST3 |
| Other compatible hosts | Audio Unit or VST3 | VST3 |
Choose the external key track in your DAW’s native sidechain menu, then select External in 6386e. Routing options depend on the host.
Build and validation notes
The 2.0.0 packages are built and tested on our build Mac: macOS natively (Apple Silicon) and Windows x64 under Wine. Checks cover the circuit’s harmonics and release times against published figures, processor state including sessions from 1.x, mono/stereo routing, external sidechain isolation and AU bus formats. The Mac build includes an Intel binary slice; runtime validation of that slice is not claimed. Individual DAW versions may have different requirements.
Installation & activation
Install on macOS
- Save your project and close your DAW.
- Open the DMG and launch 6386e Tube Compressor Setup. Review the licence terms, then select Audio Unit and/or VST3 and choose Install. Logic Pro needs Audio Unit.
- Install for your Mac account, reopen your DAW and rescan plug-ins if needed. No administrator password is needed for this per-user installation.
Manual ZIP: copy the complete 6386e Tube Compressor.component bundle to ~/Library/Audio/Plug-Ins/Components/ and 6386e Tube Compressor.vst3 to ~/Library/Audio/Plug-Ins/VST3/.
Install on Windows
- Save your project and close your DAW.
- Run the Windows Setup file, review the licence terms, and choose Install.
- Reopen your DAW, enable VST3 plug-ins and rescan if needed.
Manual ZIP: copy the complete 6386e Tube Compressor.vst3 bundle to C:\Program Files\Common Files\VST3\. Keep the bundle intact.
Activate and work offline
Open 6386e in your DAW. If it is not authorised, choose Find my licence to open your AudioNode account. Enter your licence key, or import your licence file, then choose Activate.
After activation, the key field is hidden. Choose Manage my licence to open your account or Return to plugin to continue. The plugin does not save your licence key. It saves a signed authorisation for this computer and periodically renews it online, normally after one day. Each offline authorisation lasts at most 30 days from its successful issue; opening the licence panel does not start a new offline period.
If authorisation expires or cannot be verified, audio passes through without compressor processing. Saved projects and settings remain. Restore authorisation before final playback or export. Manage your computers through your AudioNode licence account, deactivating an old computer before adding a fourth.
Route an external sidechain
- Insert 6386e on the track or bus you want to compress.
- Use your DAW’s sidechain routing to send the trigger track into 6386e’s external input.
- Select External in 6386e and adjust Threshold and Time Constant. With an external key the detector isn’t fed back from the output, so start with a lower Threshold. Use Sidechain HPF to reduce bass influence on detection.
The external key controls compression and is never mixed into the output. Input Gain changes the main audio’s drive, not the external key level. Without a connected key, External receives silence; it does not switch back to Internal automatically.
Update or uninstall
Download future versions from your AudioNode account, close your DAW and run the newer installer. It backs up earlier owned copies and preserves your projects and settings. Projects saved with 1.x open on the nearest 670 settings in 2.0; they will sound different, and automation of removed controls no longer applies.
On Mac, run Uninstall 6386e Tube Compressor from Applications/Fletcher Audio to remove the selected formats. On Windows, use Settings → Apps → 6386e Tube Compressor → Uninstall. Projects using a removed plug-in will report it missing.
What is included?
6386e 2.0.0 for macOS and Windows, AU and VST3 formats, all 11 automatable controls, external sidechain detection, Meter/Graph views, installer and manual ZIP, plus a 17-page guide with four circuit sheets and the complete licence agreement.
Fletcher Audio · Salisbury, Wiltshire, United Kingdom.
Support: hello@audionode.io