Softube Bus Processor 670 Unveils Vintage-Modern Sound

Softube has introduced the Bus Processor 670, a cutting-edge plugin that reimagines the iconic Fairchild 670 dual-channel variable-mu tube compressor. Known for its historical impact as a mastering limiter for vinyl, the Fairchild 670’s harmonic character graced legendary recordings from Motown to Abbey Road. The Softube Bus Processor 670 aims to capture this ‘magic’ with modern enhancements, featuring saturation knobs for tube and transformer saturation, alongside a calibration knob that allows precise control over compression-dependent saturation. This release underscores Softube’s commitment to merging classic sound with contemporary technology, drawing on its support for the Console 1 mixing system and Flow Studio hardware ecosystem.

The Fairchild 670 is renowned as a legendary piece of audio equipment, originally developed to serve as a mastering limiter for vinyl records. Its distinct harmonic character played a significant role in shaping the sound of classic recordings. This compressor was pivotal in the production of music spanning from the soulful tunes of Motown to the revolutionary tracks recorded at Abbey Road.

Technically, the Fairchild 670 is a dual-channel variable-mu tube compressor, renowned for its ability to impart a smooth and musical compression. The device’s variable-mu architecture introduced a unique compression characteristic that many engineers sought after for their recordings. Today, its sound is still highly revered, leading to modern reinterpretations like the Softube Bus Processor 670 that aim to replicate this classic audio quality while integrating contemporary digital enhancements.

The Bus Processor 670 offers dedicated saturation controls that include separate knobs for tube and transformer saturation, together with a calibration knob that influences the compression-dependent saturation of the plugin’s variable-mu architecture. These controls are presented as front-line tonal-shaping options intended to emulate the harmonic behavior associated with classic variable-mu designs. The calibration knob is described specifically as affecting how saturation interacts with compression, linking tonal coloration to the compressor’s gain-reduction characteristics. This arrangement allows users to alter harmonic content in ways tied to the plugin’s compression behavior.

Sidechain functionality in the Bus Processor 670 includes selectable controls for filters and a tone-shift option, and it provides mono/stereo linking within the sidechain path. The plugin also exposes separate outputs for mid/side (M/S) channels, enabling discrete routing of those channels from the processor. These sidechain and routing features provide targeted control over how the compressor responds to program material and how the processed signal can be delivered in a mixing or mastering context. The inclusion of tone-shift and filter controls in the sidechain reflects an emphasis on shaping the detector path to influence compression behavior.

Spatialisation features in the plugin comprise an air band, a mono maker, and a stereo widening knob as part of its toolkit for adjusting perceived depth and width. These elements are provided alongside the processor’s core dynamics and saturation functions to offer broader control over stereo image and high-frequency presence. Softube also supports integration with the Console 1 mixing system and the Flow Studio hardware ecosystem for workflow and hardware control. The combination of dynamics, saturation, spatial tools, and hardware integration positions the plugin as a multi-faceted processor within the Softube product lineup.

The Softube Bus Processor 670 plugin is available at an introductory price of $99. Once the introductory offer ends, the regular price of the plugin is set at $149. This pricing strategy allows early adopters to access the plugin at a reduced rate.

In addition to standalone purchase options, the Bus Processor 670 is included in various subscription packages. Softube incorporates this plugin into its Flow Mixing, Mastering, and Complete Suite subscriptions, offering users flexibility in accessing the plugin through these service bundles.

This approach provides additional value for those already engaged with Softube’s subscription services, enabling access to the Bus Processor 670 as part of a broader professional audio toolset.

Softube described the Bus Processor 670 as ‘full-featured but dead-simple to use’ in its announcement. The company said the plugin ‘lets users find the magical sound of the 670 for themselves.’ Softube added that the product delivers ‘a workflow that works for the modern music maker.’

CONCLUSION

Softube has released the Bus Processor 670 plugin, a modern take on the Fairchild 670 dual-channel variable-mu tube compressor designed to capture the original unit’s harmonic character. The plugin includes saturation knobs for tube and transformer saturation, a calibration knob that affects compression-dependent saturation, sidechain controls for filters, tone shift and mono/stereo linking, and separate outputs for mid/side channels. Spatialisation features comprise an air band, a mono maker and a stereo widening knob, and Softube supports integration with its Console 1 mixing system and the Flow Studio hardware ecosystem. The Bus Processor 670 is available at an introductory price of $99 with a regular price of $149 and is included in Flow Mixing, Mastering, and Complete Suite subscriptions.