Compressors can be a real mystery to guitarists who don’t understand the concept. Recording engineers bandy about words like “hard-knee” and “soft-knee” compression, “ratio,” “threshold,” and “transparency”; these are not guitarist-friendly terms. A test run on Pettyjohn’s Crush presents a good opportunity to discuss compressors in everyday guit-box talk.

Let’s start with the phrase “studio-grade.” Pro players who have worked in studios know the power and glory of rack compressors like the classic UA 1176, LA-2A, and Distressor, as well as those built into old-school mixing boards. Those circuits simply make electric and acoustic guitars and basses sound fatter and more robust and polished than if they went straight into an amp and to tape. Just ask David Gilmour, who cut more than a few great Pink Floyd parts by plugging his Strat straight into a mixer and skipping amps altogether.

Designed for live work and home-studio applications, the Crush has a discrete VCA compression chip made specifically for Pettyjohn and delivers high headroom and that all-important transparent tone. Transparency is critical in guitar compressors because, while one may occasionally desire “squishy” compression (as available with cheaper pedals), most times, a player wants to hear their guitar and amp compressed without coloration. A knob here called Tilt EQ lets you tweak the EQ to taste, from big-and-bassy to a brighter tone, as compression can sometimes steal a little high-end response.

In the middle of the Crush are two switches. Ratio offers 2:1, 4:1, and 10:1 selections that change the amount of “crush”; Release offers Medium, Short, and Long release of the compression effect, with the last one enhancing sustain. Elsewhere, the Level control adds back any volume diminished in higher compression settings, while Clean Mix balances the compression circuit with the straight guitar tone, useful in retaining a natural tone.

In tests, the Crush delivered formidable compression power, tone control, and transparency. If you wince at the price, consider that serious players and engineers gladly pay for superior sound. You can certainly grab a $100 compressor, but you will likely get a colored, squishy tone and limited flexibility. If, on the other hand, you’ve been inside a studio and heard an engineer add sweet compression to a guitar or bass track, you understand the potential of the Pettyjohn Crush. Simply put, it’s a powerful and flexible pro compressor in a stompbox. That’s a big deal.

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