Dr. Z Z-PLUS Review

These days, low-wattage amps are a staple of the boutique amp business. The best of these can cover everything from small club gigs to arena rock shows. And depending on the design philosophies of their creators, they can sound quite unique, too. Dr. Z’s new model, the Z-PLUS, is no exception. It’s a 1x12 combo that weighs in at 38 pounds and kicks ass across classic American and British tone dimensions.

The Z-PLUS is switchable between 7 and 15 watts, and has a familiar front-panel control set: volume, treble, mid, bass, cut, reverb, and master volume. It also features the company’s variable boost footswitch (included), which partially bypasses the amp’s tone stack via a variable potentiometer to provide boost that you can adjust via a side-mounted dial. And if you’re a dirty player who craves spanky lead sounds, the boost—and the way the Z-PLUS achieves it—pays off big time.

Paging Dr. Z
We’ll discuss the Z-PLUS’ performance in more detail momentarily. But, for now, here’s the backstory. After borrowing a Dr. Z MAZ 8 for a 2006 reunion recording session with the James Gang, Joe Walsh bought the head and took it on the road. The MAZ 8 became a staple of Walsh’s setup with the Eagles, alongside a Fender Deluxe. But as the Eagles’ respective ages increased, so did their vocal microphone levels, so Walsh asked Mike Zaite (a/k/a Dr. Z) if he’d make a quieter amp that would bleed into vocal microphones less.

Zaite, who’s been building amps for 30 years, agreed. Knowing that Walsh used filthy-sounding 5-watt, class A Fender Champs for the raunchy James Gang hits “Walk Away” and “Funk #49,” he decided to start with the single-ended output construction used in those amps. Then he and Walsh turned to hi-fi audio amplifiers for further inspiration. The result is a class A amp with a single-ended output stage that allows full reproduction of even-order harmonics (unlike class A/B push-pull output stages that cancel out second- and fourth-order harmonics). Typically class A amps are limited by lower headroom, but the Z-PLUS uses two 6V6 power tubes in parallel to increase headroom.

For an engineering half-wit like me, it sounds complicated. And even Zaite says it was a tough design to bring to life. But plugging a Les Paul, a Stratocaster, and my Zuzu into the Dr. Z-PLUS, I heard the natural voices of the instruments—plus the overdrive, volume, tonal flexibility, and textural richness that an excellent, lively amp brings to the game.

Road Worthy
The Z-PLUS’ is built into a 19 1/4” x 19 ½” x 10 ½” box made of Italian poplar, a wood that’s lighter than pine but just as resonant. The reverb tank—excuse me: the lush, resonant, crazy-deep-sounding reverb tank—is vertically mounted to the right of a Celestion Alnico Blue G12 speaker. (The Celestion option costs another $200, versus a Dr. Z speaker, but Zaite suggests the extra bark is worth the extra bucks, and I agree.) On the back, there are 16-, 8-, and 4-ohm speaker outs, the boost switch input, and the full/half power switch. The test model was dressed in red vinyl, which complimented the simplicity of the black control panel and the grey-black grille cloth that reminded me of my grandmother’s old floor radio.

Besides power and standby switches, the front panel also has hi and low input jacks—another nod to Z-PLUS’ vintage inspirations. In addition to the two 6V6 power tubes, there are four 12AX7s and one 12AT7 for the preamp, and a 5AR4 rectifier tube. (There’s a handy chart of the tube layout on the amp’s left interior wall). The custom-built Heyboer output transformer plays an important role in the Z-PLUS’ hi-fi sound. There’s also a healthy array of filter capacitors under the hood, which Zaite explains were necessary to cut humming and noise.

As I played through the amp alone, in rehearsal, and at a gig, I discovered that I loved leaving the boost activated. Tweaking the footswitch’s variable boost control along with the volume and master delivered big, open, harmonically rich, mid-heavy tones at different volume levels. Keeping the boost on means you don’t always have full use of the tone stack. And many amps provide a similar function by removing the tone stack completely. But by using a variable potentiometer connected to the midrange potentiometer’s ground, The Z Plus enables the player to preserve varying degrees of tone stack functionality when the boost is on.

What’s really cool, though, is that the tone remained consistent switching between 7 and 15 watts. Perhaps that’s because the Z-PLUS keeps both tubes in use at all times where many power reduction circuits simply bypass a tube. And while 7 watts was totally sufficient to fill a 200-capacity venue with a little reinforcement (I am thrilled by how loud today’s best low-wattage amps are!), I really enjoyed the headroom available at 15 watts.

Plugging into the hi or low input was a matter of whim. The amp’s sparkling, punchy sound cut through the band mix regardless of which I chose. I also got plenty of break-up or clean headroom without the boost simply by adjusting the volume and EQ controls, though partially bypassing the tone stack made every note sound a bit more open. A note about that dreamy reverb: After 3 o’clock it dives past surf textures into ambient/shoegaze territory. I enjoy that, but if playing inside the envelope, rather than pushing it, is your thing, you may want to remain in its lower reaches.

The Verdict
The Dr. Z Z-PLUS is a well built, great-sounding amp that transcends American-design roots to include driving, classic British style sounds. It’s built like an armored car. And it’s versatile enough—thanks to the tone-shaping options and variable power level—to handle any stage or studio gig short of screaming, high-gain metal. It’s robustly priced at about two grand. But if you’re interested in owning just one do-it-all amp, this could be it—making it worth every cent.

Watch the Review Demo: