Electric guitars with passive pickups are fickle things, as their sound is affected by the load they drive (the impedance of the connecting cable and the input impedance of the amplifier or pedal to which they’re connected), and this loading not only results in high frequency loss but it also affects the resonant frequency of the pickups.
IK Multimedia’s Z‑Tone products puts the user in control of these variables, by equipping a high-quality instrument preamp with the means to adjust the input impedance to best suit the instrument. There are two related products on review here, the more compact Z‑Tone Buffer Boost and the larger Z‑Tone DI.
Taking the Buffer Boost first, this takes the form of a dual footswitch stompbox. It features a transformer-balanced, 600Ω XLR output, with ground-lift switch, for feeding mixers or audio interfaces. There’s also a buffered, unbalanced quarter-inch output jack with a 56Ω impedance. A Link jack is wired in parallel with the guitar input jack, and this can be used to feed the signal on to an amp with the benefit of the variable impedance.
The Z‑Tone Buffer Boost can be powered from a 9V battery, a 9V pedal power supply or 48V phantom power; phantom takes precedence over the battery when present. Its preamp can be switched from JFET to Pure. The JFET mode, which uses a discrete junction gate field-effect transistor, adds a little harmonic colour, whereas the Pure mode sounds very clean.
The preamp can be switched to suit passive or active pickups too — the latter have a lower impedance than passive ones and aren’t affected by load impedance in the same way. In Active mode, the Z‑Tone control, which adjusts the impedance between 1MΩ and 2.2kΩ, is bypassed and a fixed 20kΩ impedance is employed instead.
There are just three knobs to adjust: Gain, which works on the input; the Z‑Tone Sharp/Bold knob, which controls the impedance; and Boost, which can add up to 10dB of gain. The leftmost footswitch is Bypass, and the rightmost one brings in the Boost. Both have status LEDs
