Model 670
Vari-Mu Compressor
The Z&H Designs 670 is a faithful resurrection of the most revered compressor ever created. Built on the complete, unmodified original circuit, it delivers the unmistakable weight, depth, and harmonic movement that defined decades of legendary recordings. From its massive hand-wound transformers to its tube-driven gain structure, every detail exists to recreate the breath, size, and authority of the original. This is not a reinterpretation or a compromise. It is a living, breathing instrument that shapes sound with richness, scale, and emotional gravity. Once heard, it cannot be replaced.
Unmodified Original Circuit
The Z&H 670 is built on the complete, unaltered original 670 circuit. No shortcuts, no redesigns. This preserves the authentic gain behavior, harmonic movement, and dynamic response that defined the sound of legendary recordings.
Authentic Transformer Architecture
Eleven custom-designed transformers replicate the original core sizes, materials, DCR, and inductance. This restores true low-frequency weight, natural saturation curves, and correct sidechain behavior that modern substitutes fail to achieve.
True Tube Flexibility
The standard configuration uses a carefully tuned T-Bar design with 6BA6 tubes for stability and reliability. Dedicated sockets allow direct installation of original 6386 tubes for those pursuing absolute vintage authenticity.
Modern Workflow Enhancements
Extended time constants, sidechain filtering, true bypass, and stereo gain trim expand functionality without altering the original signal path. These additions make the 670 practical for contemporary tracking, mixing, and mastering.
Reliable Modern Engineering
A modern LDO linear power supply with auto-detect global voltage and an integrated internal layout dramatically improves noise performance, stability, and long-term reliability compared to vintage units.
Built for a Lifetime
Each unit is professionally assembled, shipped in a custom wooden crate, supported by a global service network, and protected by a five-year warranty for long-term peace of mind.
FEATURES
- Completely unmodified original 670 circuit design
- Eleven custom hand-built transformers based on vintage originals
- Selectable tube configurations: standard T-Bar (6BA6) or optional 6386
- Extended time constants with sidechain filtering
- True bypass and stereo gain trim for modern workflows
- Modern LDO linear power supply with auto-detect global voltage
- Integrated internal layout for superior reliability and low noise
- Pre-wired sockets for direct 6386 installation
- Professional wooden shipping crate included
- Five-year warranty with global service support
Specifications
| THD + N | < 0.05% typical; < 1% @ 20 dBu |
| Noise Floor | < –83 dBu (AP tested); < –90 dBu (via AD/DA in DAW) |
| Maximum Output Level | 20 dBu (1 kHz, THD < 1%) |
| Maximum Gain | 20 dB |
| Power Consumption | 300 W |
| Dimensions (W × H × D) | 482 × 352 × 300 mm (including deepest point) |
