Tube Driver

The Tube Driver is a valve-based overdrive circuit designed by B.K. Butler, best known from the Chandler and Tube Works pedals of the 1980s and now sold under Butler's own Butler Audio name. Where most overdrive pedals clip the signal with silicon, the Tube Driver gets its character from a real preamp valve running inside the box, which is why it has stayed on the radar of players chasing a full, singing lead tone. Butler Audio states that the current version keeps the original design and sound, "as supplied to Eric Johnson, David Gilmour, etc," with improved parts such as Switchcraft all-metal jacks and click pots¹.

Guitar World's Trevor Curwen describes it as "that large mains-powered valve-based overdrive," and counts David Gilmour, Eric Johnson, Billy Gibbons, Joe Satriani and Joe Bonamassa among the players seen using it².

Where the Tube Driver came from

The Tube Driver began as a mains-powered valve overdrive, a format that set it apart from the compact battery-powered pedals of its era. Guitar World notes that it was a large unit, and that its mains transformer brought hum with it as a drawback². That size and power requirement were the price of running a real valve at a real operating level rather than starving it the way smaller designs could.

The circuit passed through several brand names on its way to its current form. It appeared as the Chandler Tube Driver and under Tube Works branding before B.K. Butler began selling it himself. Butler Audio's own pages state that "TubeDriver, TubeDriver BLUE, Thermionic, MosValve, Butler Audio, Blue Tube" and the "blue tube illumination, appearance and method are trademarks of BK Butler"³. For players hunting originals on the used market, this means a Chandler, a Tube Works and a Butler Audio Tube Driver can all be the same basic circuit under different labels.

How it works: a real valve driven inside a pedal

The core idea is straightforward: instead of diodes or an op-amp doing the clipping, a preamp valve does it. The original featured an ECC83, the European designation for the 12AX7 family, and Guitar World notes that users sometimes changed it for an ECC82, a lower-gain valve that alters how hard the stage drives²⁴. That valve swapping is part of the Tube Driver's appeal for tinkerers, since the tube is a socketed, user-replaceable part.

Running a valve properly inside a pedal takes voltage, which is why the original was mains powered rather than battery powered². The same approach shows up across the modern tube-pedal category, and it illustrates what the Tube Driver started:

The contrast with conventional overdrives is the point. MI Audio described its DIY Dual Drive kit as "two channels of op-amp based overdrive and/or distortion designs," which is how the vast majority of overdrive and distortion pedals work: integrated circuits clip the signal, and any "tube" character is voiced in rather than generated⁹. LunaStone's Steen Grøntved put the tube-pedal goal plainly when explaining his own designs:

The Tube Driver took the opposite route: it puts the real tube in the pedal and lets it do the work¹¹¹².

Versions: pedal, rackmount and the AC powered model

Guitar World notes that "when you take into account both the pedal and rackmount versions, there have been lots of Tube Driver variations"². The rackmount format suited the valve circuit's size and mains power needs, and both formats found their way onto pro rigs.

The version players most often ask about is the AC powered Chandler model associated with Eric Johnson. In a November 2001 ToneQuest Report interview, Analog Mike described trying to find good examples of Johnson's pedals, "like the silicon Fuzz Face and AC powered" Chandler tube driver¹³. Catalinbread adds a detail about how Johnson ran his: "Eric Johnson used to run his Echoplex before his BK Butler Tube Driver, preferring the sound of a saturated echo"¹⁴. That ordering, with the Echoplex echo feeding the overdrive rather than following it, is now a documented part of his setup.

Who used it

The player list is unusually strong for a single circuit. Guitar World names David Gilmour, Eric Johnson, Billy Gibbons, Joe Satriani and Joe Bonamassa as players seen using it². A Voodoo Lab demo describes "a vintage B.K. Butler Tube Driver used by David Gilmour and Eric Johnson among others"¹⁵.

Gilmour's association extends to related tube gear from the same era. Pete Cornish reports that "in 1997 we had built a 4 channel tube line driver for David Gilmour's studio, Astoria," a device for isolating long guitar-to-amp cables rather than an overdrive¹⁶. Players chasing Gilmour's later lead tones have also looked at the Pete Cornish G-2 distortion path, a separate line of inquiry from the Tube Driver itself.

Pedals inspired by the Tube Driver

The Tube Driver's influence runs through both production pedals and the DIY world¹⁷¹⁸¹⁹:

• Lovepedal Hermida Audio Dover Drive: described by its maker as "inspired by the tube-driven B.K. Butler and Chandler Tube Driver pedals" that the maker credits with powering players including David Gilmour's late-model rig²⁰.
• madbean Archibald: a DIY build documented in madbean's 2022 manual as "Based on the BK Butler® Tube Driver™"¹⁷.
• Crazy Tube Circuits Venus: a "Real tube (12AY7) overdrive" in the maker's own words, part of the current wave of pedals putting a genuine valve in the box²¹.

The DIY scene around the circuit matters here. Because the Tube Driver is a relatively simple valve stage rather than a proprietary chip, it has been reproduced in kit and PCB form, which keeps the circuit in circulation even among players who build their own. The wider tube-pedal category it helped start, from the Broughton Sonoran to the Friedman Motor City Drive, all follows the same principle the Tube Driver established: a real valve, run at real voltage, inside a pedal⁴⁸.

Tube Driver versus the Tube Screamer

The Tube Driver is sometimes confused with the Tube Screamer, but the two circuits are unrelated. The Tube Screamer was designed by Susumu Tamura in 1979. The Tube Driver, by contrast, features a real ECC83 valve inside, with a tube run at low voltage creating the distortion. Tone City's Green Tube shows how the naming tangles: the maker calls it "our latest tribute to the classic TS overdrive", a Tube Screamer-style circuit with "Tube" in the name but no valve in the circuit. When a pedal says "tube," the question worth asking is whether a valve is actually in the signal path, and with the Tube Driver the answer is yes²²¹²¹¹.

Pedals on this page

Chandler Industries Tube Driver

Chandler Industries · Overdrive

Dunlop Fuzz Face

Dunlop · Distortion

$149 list price

Maestro Echoplex EP-3

Maestro · Delay

Hermida Audio Dover Drive

Hermida Audio · Overdrive

$200 list price

Crazy Tube Circuits Venus

Crazy Tube Circuits · Overdrive

$312 list price

Ibanez Tube Screamer

Ibanez · Overdrive

$87 list price

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