Radial BigShot ABY: One Guitar, Two Amps, Zero Hum

The Radial BigShot ABY is a 100% passive, true-bypass amp switcher that routes one guitar to two amplifiers, amp A alone, amp B alone, or both together in Y mode, from a pair of rugged footswitches. It carries a full isolation transformer and a ground-lift switch to kill the hum that erupts the moment two amps share a guitar, plus a 180-degree polarity switch to phase-match them and a separate, always-on tuner output for silent tuning. For the player who has always wanted to run a clean amp and a dirty amp together but got buried in buzz, the BigShot makes a two-amp rig finally sound as big as it should.

What an ABY Switcher Does

An ABY is a routing pedal that gives one instrument access to two amplifiers. Hit the A footswitch and your signal goes to amp A; hit B and it jumps to amp B; engage both and you are in Y mode, playing through both amps at once. That opens up sounds a single amp cannot make: switch between a clean combo and a high-gain stack as the song calls for it, or run them together so a clean amp adds sparkle and body underneath a saturated one. The BigShot puts all of that under two footswitches you can hit without looking down.

Why Two Amps Hum, and How the BigShot Fixes It

The moment you plug one guitar into two amplifiers, you connect their two power supplies together through the guitar's ground, and the difference between them creates a ground loop, a circulating current that shows up as loud 60-cycle hum. The BigShot breaks that loop two ways. Output B runs through a built-in isolation transformer that passes your audio while blocking the DC path feeding the loop, and a ground-lift switch fully floats Output B's ground when needed. Between them, the two amps stay electrically separated and the hum simply disappears.

Polarity: Phase-Matching Two Amps So They Reinforce

Isolation solves the hum, but two amps running together can still fight each other. If one amp's signal is electrically inverted relative to the other, their low frequencies cancel and the combined tone goes thin and hollow, a problem you can hear but not easily explain. The BigShot's 180-degree polarity switch flips the phase of Output B so both amps push and pull together. Flick it to whichever position sounds fuller and the two amps lock in, their low end reinforcing instead of subtracting, for a combined sound with real weight and punch.

True Bypass and a Passive Signal Path

The BigShot's audio path is 100% passive and true-bypass, meaning your guitar signal flows through switches and a transformer with no active circuitry to color it, giving a measured insertion loss of just -0.3 dB across a full 20 Hz to 20 kHz frequency response. Because the audio is passive, the pedal works with no power connected at all. The optional 9V DC supply only lights the status LEDs; it never touches your tone. That is a deliberate design choice, so your signal stays exactly as pure as the amps make it, powered or not.

The Silent Tuner Output

A dedicated tuner output sits on the BigShot and stays live at all times, feeding your tuner continuously no matter which amp is selected. That means you can mute both amps, tune in total silence between songs, and never send a note of tuning to the audience. It is one of those small features that quietly transforms a live set: no more tuning noise over the PA, no more juggling a separate mute pedal, just a clean, professional stage presence every time you check your pitch.

Built Like a Tank

The BigShot lives inside a folded 14-gauge steel chassis engineered to survive the stage. The heavy-gauge shell shrugs off stomps, drops, and the crush of a loaded gig bag, while recessed switches and rugged 1/4-inch jacks keep the signal solid show after show. Radial builds these switchers to be stepped on for years, which is why you find them on so many professional pedalboards that tour hard and never miss a night. This is a tool bought once and trusted for a career.

Who the Radial BigShot ABY Is For

The BigShot ABY is for the gigging guitarist running two amps who is tired of ground-loop hum; for the player who wants to switch cleanly between a clean amp and a dirty amp mid-song, or blend them for a bigger sound; and for anyone who wants a silent tuner output built into the same box. If you have ever wanted the size and flexibility of a two-amp rig without the noise and hassle, the BigShot ABY is the true-bypass switcher that makes it effortless.