Bus Processor 670 by Softube dual-channel tube compressor plugin interface

Bus Processor 670: Variable-Mu Tube Bus Compressor by Softube

Rated 4.8/5 on Plugin Boutique (6 ratings)

Bus Processor 670 is a dual-channel variable-mu tube compressor plugin from Softube, modeled on the legendary 670 hardware. It adds saturation, sidechain and spatialization controls for mixing and mastering.

VST3VST2AUAAXRTASWindowsmacOS64-bit

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01Overview

Bus Processor 670 is Softube's modern take on the rare 670 variable-mu tube compressor, originally used as a mastering limiter. The developer describes the aim as distilling what makes the original sound distinctive: weight, warmth and cohesion. It works as a native plug-in and is also compatible with Softube's Console 1 and Flow Studio hardware. Beyond the classic compression character, it adds saturation controls, sidechain options and spatialization tools for a more flexible workflow.

Best for

Mix bus glue
Mastering compression
Drum bus processing
Vocal warmth
Electric guitar tone
Analog-style cohesion

Developer: Softube
Category: Compressors
Store: Plugin Boutique

02Key features

What you get

Dual-channel variable-mu tube compressor modeled on the 670
Dedicated tube and transformer saturation controls
Calibration knob for compression-dependent saturation
Sidechain filters, tone shift and mono/stereo linking
Separate outputs for M/S channels
Air band, mono maker and stereo widening knob
Compatible with Console 1 mixing system hardware
Compatible with Flow Studio hardware

03In depth

Sound and Character of the 670 Compressor

Variable-mu compression uses tubes to change gain, so the compression ratio shifts with the signal level. This produces the harmonically rich compression the original 670 is known for. Softube says the plug-in captures its weight and warmth, and the original is said to add sound and harmonic distortion even at light settings.

At subtler settings the unit is used to glue elements together in a warm, musical way. More aggressive settings produce pumping. The developer positions it for mix buses, drums, vocals and electric guitars, as well as mastering.

Controls for Saturation, Sidechain and Spatialization

Dedicated knobs control tube and transformer saturation, and a calibration knob influences the compression-dependent saturation of the variable-mu design. The sidechain section offers control over filters, tone shift and mono or stereo linking, with separate outputs for M/S channels.

Spatialization features include an air band, a mono maker and a stereo widening knob. Softube describes the interface as full-featured but straightforward to use.

04Specs

Will it run?

Formats, systems and requirements as listed by Plugin Boutique. Missing details are left out, not guessed.

Developer	Softube
Type	Plugin
Category	Compressor
Formats	VST3, VST2, AU, AAX, RTAS
Operating systems	Windows, macOS
Architecture	64-bit

05FAQ

Questions, answered

Which formats and operating systems does Bus Processor 670 support?

It is available in VST3, VST2, AU, AAX and RTAS formats, with support for Windows and macOS. The developer notes that TDM, VENUE and RTAS are no longer supported, and that VST3 is recommended.

What do I need to use Bus Processor 670?

You need a supported 64-bit host (AU, VST, VST3 or AAX-compatible), a Softube account and an iLok account. macOS Big Sur 11 or later, or Windows 10 or 11 (64-bit), is required, along with internet access for installers and licenses.