As well as adding a chewy harmonic Class A-style complexity, the Zia exhibits a bumped-up midrange like a Vox amp
Like all the other pedals in the Durham Electronics range, it’s designed for a particular purpose. This is not intended for massive gain or endless sustain, nor even intended for soloing: it’s aimed squarely at rhythm guitar applications where tight low end and clarity are paramount. Even more specifically it’s designed to make amps with Fender-style 6V6 and 6L6 power tubes sound like they’re loaded with Vox-style EL84s. If the promo blurb is to believed, this pedal is a must for early Rolling Stones fans.
The Zia shares the same look as all the other Durham pedals, but it’s smaller. Three knobs control Level, Gain and Tone, which is supposedly neutral at 12 o’clock. Despite the presence of a 3PDT footswitch the Zia is not true bypass: Alan Durham doesn’t like it. He also believes that cloning is best confined to sheep, but you can order Durham pedals with true bypass if you want.
The Zia takes a battery or a 9v negative tip power supply and it comes with a two-year warranty for the original owner. If anything does go wrong you probably won’t be able to fix it because the components are disguised and fixed solidly in place by epoxy resin.
The Zia can be used as a fairly clean boost, although I had to back the Tone control right off to achieve a ‘unity’ setting through my slightly dark tweed Deluxe. Like the Durham Sex Drive the overall enhancement in clean boost mode might encourage you to leave it permanently switched on, and even the clean sounds are clearer and sweeter because this pedal cleans up so well off a guitar volume control.
To achieve that clean boost it’s best to run the level flat out and then turn up the Gain. Like a non-master volume valve amp the Zia‘s overdrive comes on very gradually, and things seem so integrated that the volume control on your amp almost becomes a fourth control knob on the pedal. Or maybe it’s the other way around. Regardless, all those interactive controls means you can get compression-free overdrive from the pedal with a loud clean amp, or enjoy a combination of amp and Zia overdrive.
As you might expect the Zia‘s true voice becomes more apparent at higher Gain settings. As well as adding a chewy harmonic complexity I’d associate with Class A (or pseudo Class A) valve amps, the Zia starts to exhibit a bumped-up midrange that’s peculiar to Vox amplifiers. Some attribute this midrange honk to the notch filtering that Vox used to eliminate low frequency thumps from the vib/trem circuit. Obviously that doesn’t apply here, but the Zia certainly nails the tone.
However the Zia is set, it always manages to sound sweet in the treble. The high notes chime, roots and fifths on the low strings really grind and there's never any mush. The dynamics and sustain characteristics of your amp aren't messed up either, but although you can dial in some great lead tones you won't really get the singing sustain of, for example, a Tubescreamer type circuit... but that's why the Zia is so good at the job it was designed for.