Tested by Art Thompson After looking into digital technologies (see sidebar, “Taming the Piezo”), Markure and his team came up with the relatively low-tech Cool Tube, which is the world’s first onboard tube preamp for acoustic guitars.
The love/hate relationship guitarists have with piezo pickups was a primary reason why Takamine’s Mike Markure decided to design a new guitar preamp that would dramatically enhance the sound generated by piezos.
The hybrid unit features active solid-state tone controls, a built-in tuner, and a genuine 12AU7 dual-triode—a lower-gain cousin of the popular 12AX7. The Cool Tube has dual inputs: one for the stock under-saddle piezo pickup and an auxiliary input for use with the pickup, or mic of your choice. Included are individual level controls for the tube circuit and the auxiliary source, a global Volume slider, 3-band EQ, a Frequency control (semi-parametric midrange filter), and a chromatic tuner, which, when activated, disables the preamp output for silent tuning. Power for the tube and solid-state components (each of which consume three volts) is supplied by four AA batteries located just behind the removable tuner section, which slides out for quick battery replacement. The Cool Tube can operate for 24 to 26 hours on battery juice, and a switch on the back of the preamp allows the unit to be powered by an external 6-volt supply (not included). If you’re concerned about heat build-up from a tube inside your guitar, don’t be. According to Markure, the Cool Tube operates at a mere two degrees Fahrenheit above ambient temperature.
Though the Cool Tube will eventually be sold separately—a boon for owners of older Takamines—it’s currently available only on Tak’s Nashville Series, SuperNatural Series, Hirade Classics, and Santa Fe guitars (all of which are still available with the standard, non-tube CT4-B preamp).
Though some will undoubtedly scoff at the viability of a tube running at three volts, the Cool Tube definitely works. Tested on a fine-playing Takamine EAN16C ($1,929 retail/$1,349 street)—which was also equipped with a new L.R. Baggs M1 Tri-Axial soundhole pickup—the Cool Tube immediately proved its ability to produce fatter and richer amplified tones. By leaving the Baggs pickup completely off and simply turning the Cool Tube volume up and down, it was easy to hear the effect of the tube circuit as it dramatically smoothed out the piezo crinkle, adding body and thickness to the tone. As you turn up the Cool Tube control, you may actually find yourself slightly cutting lows to accommodate the circuit’s beefy contribution.
While I preferred the sound with the Cool Tube control turned all the way up, lower settings provided more piezo bite, creating textures that embody tube warmth and piezo immediacy. Blending in the signal from the Baggs M1 (which senses both the strings and the top’s motion) further expanded the sound, adding a level of complexity, depth, and richness that would be unthinkable with a piezo-only setup.
It’s always good when a highly regarded player weighs in on a new product, and it was very cool when guitarist extraordinaire John Jorgenson (Hellecasters, Elton John) showed up with Markure to demo the Cool Tube. Not only did I get to witness Jorgenson playing lots of great stuff—including his fabulous Django stylings—but I clearly heard the Cool Tube elevating an otherwise decent-sounding acoustic-electric to a new level of tonal bliss. Jorgenson even refers to the Cool Tube control as the “feel good knob” because it adds so much girth. And though Jorgenson has a vested interest in the Cool Tube (he was the primary guitarist on the product’s development team), I got the distinct feeling that the Cool Tube has become an inextricable part of his acoustic sound. And, given how long it has taken to develop a product that finally addresses the shortcomings of piezo technology, I’m betting that Jorgenson will be using the Cool Tube for a good part of the foreseeable future. It’s that good.