Automated Processing Inc. (API) is best-known for its high-end mixing consoles for broadcast and recording, along with the mic preamps, compressors, and EQs it has been making since the ’60s. The company’s discrete analog circuits are sought after for their uncolored sound. The legendary analog EQ and compression circuits in API channel strips recently became available in simplified, affordable pedals for guitar and bass players.

The TranZformer GT (guitar) and LX (bass) are housed in heavy-duty custom steel and aluminum 8″ x 5″ x 4″ chassis and weigh in at a stout four pounds. They share a layout including chassis-mounted ¹/4″ input/output jacks with phase switches, balanced XLR output connectors with ground lifts, true-bypass footswitches for the EQ and compressor circuits, and external jacks for the included 18-volt power supply.

Controls consist of an output Level control, input Gain, a three-band Tone, and a six-position Compressor knob. The boxes’ tone circuits differ in frequency – 200Hz, 1.5KHz, and 5KHz center points for the GT; 100Hz, 400Hz, and 2KHz for the LX. The compressor circuit’s threshold is affected by the Gain control; the Compressor control changes threshold from -15db to -40db while adjusting makeup gain from 0db to +18db.

Tested with a Custom Shop reissue Strat, a Martin acoustic/electric dreadnought, and a G&L L2000 bass through a variety of amps and speaker combos, the pedals lived up to API’s reputation – silky smooth and thick with natural, sweet overtones while adding zero out-of-phase clutter. The quality of the Compressor circuit leaned toward that of a rack-mount unit, with a smoother, uncolored hi-fi sound that did a great job of leveling output without squashing the tone. The only significant tone change was to top-end under heavier compression, where it took a bit of the bite from the highs, reducing harshness but maintaining a nice amount of sparkle.

The API TranZformer GT and LX are true studio-quality preamp pedals with high-fidelity EQs and compressors that will benefit any instrument.

This article originally appeared in VG March 2018 issue. All copyrights are by the author and Vintage Guitar magazine. Unauthorized replication or use is strictly prohibited.