Spiral Electric FX White Spiral

The White Spiral Boost is a JFET boost pedal from Spiral Electric FX, the company of designer Tom Cram. Unveiled at Summer NAMM 2019 and made available in late August of that year at $199, it is what the maker calls a light JFET boost: a unit meant to run always on for increased harmonic content with a little grit, or to sit last in the chain and push an amp's dirty channel¹. It is designed and handmade by Tom Cram, with a hand-brushed aluminum top and a powder-coated black bottom¹.

The circuit runs internally at 18 volts for increased headroom and uses a dual JFET for amplification². Where a clean boost leaves your tone untouched, the White Spiral is a "dirty boost": its Grit control deliberately adds a natural-sounding, low-gain grind that the maker says mates well with already dirty amp channels².

The controls: Output, Grit, Girth and the Alpha/Omega toggle

The White Spiral has three knobs and one toggle. Guitar.com described the booster as sculpted by "three main controls: Output, Grit and Girth"³, and Guitar World noted the same layout, with Girth being the control that "alternately restricts or increases bass level"⁴.

The Grit control does double duty. It both changes how the JFETs perform to create distortion and engages a silicon clipping circuit that interacts with them². Guitar.com summarized it as "responsible for shaping JFET character to produce distortion while also facilitating silicon clipping"³.

The Girth control is not a conventional tone knob. Premier Guitar's announcement described it as "a rotary cap network that either restricts bass or increases bass"¹, and the control first appeared on the White Spiral Boost's sibling, the White Spiral, whose Alpha/Omega switch changes the order of the Girth control in the circuit, pre or post Grit¹².

Alpha and Omega: where the Girth control sits

The Alpha/Omega toggle is the pedal's distinguishing feature: it makes the location of the Girth control in the circuit user-definable, switching the order of the Girth and Grit effects¹⁴.

• Alpha (A, left): Places Girth before the low-gain Grit clipping section. You choose how much bass is sent into the distortion, which changes both the character and the compression of the Grit¹³.
• Omega (right): Places Girth after the Grit control, so you decide how much bass content passes through the finished signal. Spiral Electric FX describes this mode as "open, glassy, and hi-fi-sounding" and recommends it for bassists¹³.

For a player, the practical difference is whether you are shaping the bass that feeds the distortion (Alpha) or trimming or boosting the low end of the sound that leaves it (Omega).

Where the circuit came from

The White Spiral grew out of Tom Cram's exploration of JFET circuits, initially inspired by Jimmy Page's use of the Barcus-Berry preamp². A JHS Pedals history article on the brand puts it plainly: "It was loosely based on the Barcus-Berry Preamp"⁵. Page, though, is only known to have used the preamp on acoustic².

The finished circuit is a hybrid. Delicious Audio, publishing the designer's own account, describes it as having "bits of the BB 1330S, National Semiconductor Mu-Amp, and the Yellow Spiral"². The clipping itself is a combination of JFET distortion and silicon clipping that Spiral Electric FX calls slightly asymmetrical, which the maker credits for the pedal's natural-sounding, low-gain grit¹³.

What reviewers said

Press coverage around the launch was positive about the concept. Gearnews called it "a very useful pedal to have around. Especially if you use a good valve amp!" and suggested it was worthy of consideration for making a guitar more responsive and alive⁶. Guitar.com highlighted the same quality, noting the pedal's "natural-sounding, low-gain grit that's suited to already-driven amp channels"³.

Videos

Click to load

Click to load

Click to load

Questions