Classic guitar amplifiers have made certain vacuum tubes household names (among gearheads) – 12AX7, 12AT7, 6L6, 6V6, EL84, and EL34. Working with various combinations of them along with carefully selected transformers and filter capacitors, amp builders tailor their creations to stand apart from the crowd. When Joe Walsh called Mike Zaite to discuss a custom build, he was intrigued by the twists suggested by the reticent guitar hero. The result is their fourth collaboration, the Dr Z Octal Six.

Using 6SL7 and 6SN7 “octal” (eight-pin base) tubes that were commonly employed to power the amplifiers/speakers in old home-movie projectors (which have lately become the subject of trendy conversions to guitar amps) combined with a pair of 7591 power tubes, the Octal Six has two input jacks, controls for Volume, Treble, Mid, Bass, and Master volume. An effects loop is accessed via the back panel.

With a Les Paul and Telecaster going to Input I, clean tones through the Octal Six rang with warmth and clarity dressed by a touch of chime. Rolling up the Volume control added a healthy dose of gain, sustain, and crunch; notes thickened and compressed, yet low-end stayed tight while mids were clear and articulate. With the Master and Volume running full up, the amp exuded rich harmonic sustain with a singing voice that was simply captivating. It also cleaned up nicely when rolling off the guitar’s Volume knob.

Input II was darker with less gain and presence, lending the sound even more character. Warm, melodic tones were coaxed with the Les Paul using the neck pickup, while the bridge delivered excellent classic-rock sound. No matter what it was offered, the custom-voiced Warehouse G12S/C speaker stayed warm, musical, and incredibly punchy, with a percussive response that made palm mutes and funky grooves particularly fun to play, especially with the Tele. The amp’s responsive EQ allowed dialing-in everything from warm and smooth to bright and crunchy without degradation of natural character.

The Octal Six is a remarkable amplifier offering exceptional tone, feel, and versatility. Its design is a great blend of vision and creativity, and its execution is veritably flawless. Any player looking for a cool twist on their tone in a user-friendly package can confidently add it to their list.

This article originally appeared in VG’s December 2024 issue. All copyrights are by the author and Vintage Guitar magazine. Unauthorized replication or use is strictly prohibited.