Universal Audio 710 Twin-Finity

A single-channel preamp with a knob that slides continuously from 100 percent tube to 100 percent solid-state, and a meter that shows how hard you're pushing it.

Overview

Dual-path preamps were nothing new when the 710 Twin-Finity arrived. Mix (June 2009, p.86) pointed out that Millennia, Manley, Aphex and SSL all offered some variation on the tube-plus-solid-state theme. Universal Audio made the blend continuous rather than switched. The Tone-Blending knob moves infinitely between 100 percent tube (a 12AX7) and 100 percent solid-state. The two paths stay phase-aligned across the whole sweep, so there's no cancellation or thinning as you rotate. Mix (June 2009, p.86) called that infinite traversal the genuinely new part of the design.

The 710 is a single-channel microphone preamplifier and instrument DI built into a single-rackspace metal chassis. Universal Audio's own advertising, the "Thirsty for Tone?" campaign that ran across the 2008 issues of Mix, billed it as phase-aligned blending of tube and solid-state transimpedance circuits. That's marketing language for two gain topologies, one knob, no switching artifacts. The front panel carries large input gain and output level knobs, switchable phantom power, a -15 dB pad, a 75 Hz highpass filter, polarity invert, and a mic/line selector. Mix (June 2009, p.86) measured 70 dB of gain on the review unit. A Mix "Tools of the Trade" writeup (July 2008, p.78) described the design as Class-A with high headroom and quoted more than 70 dB. The 710 can sit on a desktop or be rackmounted side-by-side with a second unit. Universal Audio sold an optional handle kit for carrying it around, and Mix (June 2009, p.86) listed that kit at $29.99.

The meter is the detail that sets the 710 apart from most preamps in its class. It has two modes. In Output mode it reads output level, as you'd expect. In Drive mode it reads roughly how hard you're hitting the tube/solid-state stage. 0 dB on the meter corresponds to 1.2 percent THD at 1 kHz, and -10 dB corresponds to 0.4 percent. Mix (June 2009, p.86) found this the most useful feature in practice, flipping between modes while working the Blend knob and the gain/level controls until the color and output level landed where the reviewer wanted them.

Price varied by source and by what was bundled. Mix (June 2009, p.86) listed the 710 at $999 with the handle kit optional at $29.99. The $999 figure appears to reflect a configuration with the rack kit and possibly the handle kit, so the price today depends heavily on which accessories come with the unit. The 710 was nominated in the Microphone Preamplifier Technology category of Mix's 2009 Outstanding Technical Achievement awards (September 2009).

A few caveats. Mix (June 2009, p.86) put "doesn't come in stereo" at the top of its cons list. The 710 is a single channel, so anyone wanting a stereo pair is buying two units and racking them together. The Blend knob and Drive meter reward patience, and this is not a preamp where you set gain and forget. The tube path is a 12AX7, not a vintage-style tube stage, so the "tube" side of the blend is a color choice rather than a reissue of anything in Universal Audio's back catalog.

Engineers who used it tended to focus on the switching flexibility. In an Electronic Musician preamp feature, Marc DeSisto-adjacent panelist Chiccarelli praised the 710 for the ability to move between tube and transistor modes, saturating the tube a little more when a source wanted weight and keeping it neutral when it didn't.

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