Locomotive Audio WT-Comp

Locomotive Audio WT-Comp (Weight Tank) is a single-channel, soft-knee vari-mu tube compressor designed by St. Louis-based Eric Strouth, drawing on the Universal Audio 175B and the Altec 436A, with some ideas borrowed from Locomotive's own Model 14B. It's the second standalone (non-500-series) tube compressor in the Locomotive Audio range, alongside the Model 14B.

Two characters in one switch

A Smooth/Drive switch changes how the 6BC8 and 12AU7 tubes behave: Smooth gives the sweet, gentle tone typical of classic vari-mu compression, while Drive pushes the tubes toward a richer, more harmonically saturated character. A fixed compression threshold (roughly 3.5-4:1 per the manufacturer's own figures) simplifies control to two main knobs: attack (12-50ms) and release (200ms-2 seconds).

Three steel transformers instead of one do-it-all part

Two transformers in the input stage and one on the output, all-steel construction, build the compressor's characteristically heavy tone. A VU meter tracks gain reduction, a TRS jack lets you pair two WT-Comp units for stereo work, and a hardwire bypass lets you compare raw and processed signal at any moment. The "Weight Tank" name points to the sonic heft the circuit adds to a signal, especially useful on vocals and bass guitar, where density and presence in the mix matter most.

KEY FEATURES

• Single-channel soft-knee vari-mu tube compressor
• Tubes: 6BC8 and 12AU7
• Smooth / Drive mode switch
• Fixed compression threshold, approx. 3.5-4:1
• Attack 12-50ms, release 200ms – 2 seconds
• 3 all-steel transformers (2 input, 1 output)
• TRS jack for stereo pairing
• Hardwire bypass, designed by Eric Strouth (St. Louis, USA)

TECHNICAL SPECIFICATIONS

• Type: single-channel vari-mu tube compressor
• Tubes: 6BC8, 12AU7
• Attack: 12-50ms
• Release: 200ms – 2 seconds
• Frequency response: 20Hz – 20kHz
• THD+N: <1%, S/N: >70dB
• Dimensions: 19", 2U
• Weight: 7kg