Updated Jul. 8, 2022

Source Audio ZIO

Boston’s pedal builder Source Audio in the last few years has seemed intent in focusing on products that take the most purely “tonal” effects to the next level. After the EQ2, a programmable equalizer, comes Zio, a multi-voice analog preamp/boost designed in collaboration with Christopher Venter, the owner and sole engineer at SHOE Pedals, who previously worked with DOD on the Looking GLass overdrive.

Although “Zio” in Italian means “uncle,” in this case the word is an acronym for Impedance (“Z” is the electrical symbol for impedance), Input (“I”), and Output (“O”), which briefly describes what this pedal does: it employs High fidelity, noise-free Burr-Brown op-amps to take the guitar’s high input, sweeten its tone and deliver a clear, warm and responsive low-impedance output that that won’t be altered by the buffered dry tones of other effect pedals in your chain.

Each of the four voicings, selectable via the Circuit knob, can push up to 20dB of boost.

JFET is the transparent option, aka clean boost.
LOW-CUT cleans up the bottom-end for a tighter sound while providing extra headroom.
STUDIO recreates the so-called “Pultec Trick,” from the legendary blue equalizers where you could simultaneously boost and attenuate the bass frequencies with two different knobs, which added clarity by cutting the “mud frequencies” and improving mid-range articulation.
E-PLEX replicates the sought-after character of the preamps of the legendary Echoplex Tape Delay units.

A separate Tone toggle offers three different levels of capacitance (or simulated cable length) to brighten or darken the tone, while the Switch toggle allows to bypass the switch for always-on use.

Here are the first videos of the Source Audio ZIO Analog Front End + Boost.

Source Audio ZIO, Builder’s Notes

The goal in creating the ZIO Analog Front End + Boost was simple yet ambitious: “Make Everything Sound Better!” ZIO is an all-analog preamp/boost pedal that includes a choice of four distinct preamp circuits, each with up to +20dB of additional output boost. ZIO is Source Audio’s first all-analog effects pedal and designed in collaboration with Christopher Venter, the owner and sole engineer at SHOE Pedals.

“The Better Box”

The word “ZIO” is an acronym for Impedance (“Z” is the electrical symbol for impedance), Input (“I”), and Output (“O”). The pedal is designed to take a guitar’s high impedance signal, sweeten the tone with any of its four preamp circuits, and output a strong, low impedance signal that won’t be altered by the buffered dry tones of effect pedals further down the signal chain. High fidelity, noise-free Burr-Brown op amps help give ZIO extreme clarity and responsive pick dynamics, while maintaining ideal body and warmth. ZIO has four distinct preamp circuits. JFET offers a completely transparent signal boost with zero coloring or distortion. LOW-CUT reduces “tubby” bottom-end for a tighter sound with added headroom. STUDIO finds inspiration from the time-honored “Pultec Trick,” a studio technique that adds clarity by cutting the “mud frequencies” and adding mid-range articulation. E-PLEX captures the focused and subtle grit of the preamps found in vintage Echoplex Tape Delay units. The ZIO’s TONE toggle offers three different levels of capacitance (or simulated cable length) to brighten or darken the tone.

FOUR PREAMP CIRCUITS

• JFET
This preamp mode is similar in character and behavior to a clean tube amp input with very low distortion. Using high quality JFET Input Burr Brown OP Amps, this mode is transparent and will not add any harshness or excessive brightness. JFET mode is also very helpful in a studio or home recording environment for delivering a more natural sound to the DI or line inputs found on many pieces of studio equipment. Due to its design, JFET mode can also interface with lower impedance line inputs without excessive loss of bass content.

• LOW-CUT
The LOW-CUT mode is designed to remove excessive low frequency rumble and buildup that makes it more difficult to get guitars (and sometimes basses!) to sit well in a mix. The LOW-CUT preamp has no impact on the low midrange or presence frequencies, and, instead, reduces the “low lows” to improve headroom and provide a tighter sound. This is especially useful on guitar neck pickups, some basses, synths, and any other sound that may be too “boomy” and overpowering in a live or studio mix.

• STUDIO
STUDIO mode is based on a pair of popular studio mixing tricks used on guitar and bass. It combines an EQ curve based on the famous “Pultec Trick” (used on records since the 1950s and still today) in combination with other tried and true methods to improve clarity. This mode provides a low mid cut to remove “mud” frequencies, a gentle presence boost in the upper midrange, and a natural-sounding high pass filter, to reduce low frequency rumble. With this mode, you can achieve a more “polished” sound that is intended to fit guitars and basses more clearly in a mix. Without all of that extra bass and mud, you also will gain more volume in the most useful frequencies. This mode works very well after fuzz and overdrive pedals for tone shaping as well!

• E-PLEX
This preamp mode is similar in character and behavior to a clean tube amp input with very low distortion. Using high quality JFET Input Burr Brown OP Amps, this mode is transparent and will not add any harshness or excessive brightness. JFET mode is also very helpful in a studio or home recording environment for delivering a more natural sound to the DI or line inputs found on many pieces of studio equipment. Due to its design, JFET mode can also interface with lower impedance line inputs without excessive loss of bass content.

Features and Specifications
• Circuit knob with four distinct preamp circuits: JFET (transparent, flat frequency curve), LOW-CUT (cuts lows without affecting mid to high frequencies), STUDIO (replicates “Pultec Trick” equalization), E-PLEX (inspired by the preamp in an vintage Echoplex Tape Delay unit)
• High quality components and Burr Brown JFET op-amps
• Output control with up to +20dB of signal boost
• 3-way Tone toggle switch with bright/medium/dark cable capacitance voicing
• 2-way Footswitch Action toggle switch (with always-on “Mute” option)
• Extra Tuner/Line Output
• True Bypass
• Input Impedance: 1 Mega Ohm (1 M?)
• Output Impedance: 150 Ohm (150 ?)
• Power Consumption: 9V DC center negative @ 20mA
• Brushed anodized aluminum housing
• Dimensions: L: 4.1 in./10.5cm x W: 2.36 in./6cm x H: 2.22 in./5.65cm (including knobs)