The BK Butler Tube Driver is a tube overdrive pedal that can do everything from light drive tones to high-gain overdrive distortion1. At its core is a real ECC83 valve run at low voltage, with the two sides of the tube cascaded into each other to create the distortion, followed by an EQ section and then the output stage2. Introduced in the 1970s, it has become what That Pedal Show calls an absolute classic overdrive pedal2, and it was famously played by Eric Johnson, David Gilmour and Joe Satriani3.
The Tube Driver was designed by Brent (BK) Butler, a keyboard player, and was originally designed for keyboards back in the 1970s4. Guitar.com dates the design to 19835. Butler built versions for Chandler Industries, and the four-knob Chandler models are generally considered the best of the several versions made6. BK Butler still makes the Tube Driver today and sells new versions direct from the Butler Audio website2.
How the circuit works
The Tube Driver's distortion comes from the valve itself rather than from diodes or op-amp clipping. As Dan and Mick of That Pedal Show explain, the signal runs through the two sides of an ECC83 cascaded into each other, and the tube, being run at low voltage, creates the nonlinear part of the overdrive2. You can also try different valves in the socket2. After the tube stages the signal goes into the EQ section and then direct to the output pot, which is not buffered, so the output pot actually controls the output impedance2.
The original models featured an ECC83 that users sometimes changed for an ECC827. The pedal is physically massive and mains powered, and Guitar World notes the mains transformer hum as a drawback of that large mains-powered valve-based design7.
The controls: EQ, output and bias
| Control | What it does |
|---|---|
| Tube Drive (gain) | Goes from very mellow and low-sounding to cranked up and ballsy overdrive9 |
| EQ | Flat at zero; as it is turned up it sounds very EQ-y with loads of bass and treble, and bringing it up puts more gain all the way through4 |
| Output | Not buffered; the pot controls the output impedance2 |
| Bias (5-knob and bias-mod versions) | Sets the operating range of the valve2 |
The bias control is the extra fifth knob on some versions, and not all Tube Drivers have it2. Butler Audio describes the bias mod version's custom Bias control as allowing you to adjust the tube characteristics over a wide range, and says it is like changing the types of tubes anywhere from a weak 12AU7 to a blistering 12AT710. On That Pedal Show's five-knob unit, lower bias settings gave a grittier, spittier, starved sound2. The FN version instead puts an extra bias pot on the back of the pedal, and turning it down should get less overdrive4.
"The Bias control allows you to adjust the tube characteristics over a wide range."
History and versions
The Tube Driver's history spans several decades and formats. The original came out in the late '70s, followed by the 1980s versions most players know, a version with bias control, reissues and current versions, plus a three-knob small pedal and rack-mount versions2. MusicRadar confirms it came as both a rack-mounted unit and as a pedal3. Taking both the pedal and rackmount versions together, there have been lots of Tube Driver variations7.
The Chandler-era pedals have their own story. Several versions of the box were made, and the four-knob models built by Butler for Chandler are generally considered the best6. Because of break-ups between BK Butler and Chandler, the different versions do not all sound the same9. A new version can be bought direct from BK Butler himself, or the old-school Chandler pedals can be found secondhand9.
Butler Audio holds trademarks on the TubeDriver name and related marks, including Blue Tube, and states that use of these trademarks is by permission only and strictly enforced. If you see a "Tube Driver" from another maker, check who actually built it.
The Tube Driver's influence runs through later designs. The Crazy Tube Circuits Venus is a compact reworking of the Tube Driver with an ECC823 valve, and the TC Electronic Tube Pilot has been read as a nod to the same circuit. The Behringer Vintage Tube Overdrive is built on the BK Butler Tube Driver circuit, and JHS found it stacks up extremely well against the original8.
What reviewers and players said
On That Pedal Show, Mick found a softness and compression on his particular unit that he really loves, possibly due to the tube in it2. The same review is blunt about the practical side: the pedal is physically massive, it is mains powered, and getting the most from the controls can be a long and frustrating learning process2.
Pedal of the Day's reviewer recommended getting any incarnation of a Tube Driver, writing9:
"Either way, if you can get your hands on any incarnation of a Tube Driver, do so. You'll be extremely glad that you did."
The used market reflects that standing. That Pedal Show found the old units command proper money on eBay and Reverb, quite rare and serious money, hard to find for anything sensible2. A Premier Guitar reviewer still owns an original BK Butler Tube Driver alongside a TS-9, using it as a reference point when judging other tube pedals11. Guitar Pedal X called the Venus the finest compact take on the Butler Tube Driver to date, which says something about how the original sets the bar12.
Videos
gilmourish
Joe Perkins
Wes Likes to Play Guitar
Questions
Who designed the Tube Driver?
Brent (BK) Butler, who was a keyboard player. It was originally designed for keyboards in the 1970s, and Guitar.com dates the design to 1983. Butler built versions for Chandler Industries, and the four-knob Chandler models are generally considered the best of them.
Is the BK Butler Tube Driver still made?
Yes. BK Butler still makes the Tube Driver and sells new versions direct from the Butler Audio website. Older Chandler-era pedals can also be found secondhand, though they command serious money on the used market.
What tube does the Tube Driver use?
An ECC83 (12AX7) valve, with its two sides cascaded into each other to create the distortion. Some users changed the original ECC83 for an ECC82, and on the bias-mod version Butler says the bias knob can make the tube behave anywhere from a weak 12AU7 to a blistering 12AT7.
What does the bias knob on the Tube Driver do?
It sets the operating range of the valve. Butler Audio says it lets you adjust the tube characteristics over a wide range, like swapping tube types. That Pedal Show found lower bias settings give a grittier, spittier, starved sound. Not every Tube Driver has the bias control.
Was the Tube Driver made as a rack unit?
Yes. The Tube Driver came both as a pedal and as a rack-mounted unit, and Guitar World notes there have been lots of variations across both formats. There were also three-knob small pedal versions alongside the classic larger enclosures.
Sources (12)
- David Gilmour Tone Building, Kit Rae (kitrae.net), 2022-05
- BK Butler Tube Driver & Crazy Tube Circuits Venus And Some Other Fun Stuff, That Pedal Show, 2025-04-04
- “A vast tonal palette from gnarly, aggressive distortion to smooth, creamy overdrive. ”: Crazy Tube Circuits cooks up a crazy tube circuit for real, MusicRadar, 2025-03-14
- Ibanez Tube Screamer Or BK Butler Tube Driver? Plus Mythos Envy Pro & Hagerman 12AX7 Overdriver, That Pedal Show (YouTube), 2024-11-08
- Crazy Tube Circuits Venus review, Guitar.com, 2025-09-03
- The Best Guitar Effects Pedals of All Time, GuitarPlayer (www.guitarplayer.com), 2021-06-25
- Crazy Tube Circuits Venus review, Guitar World, 2025-07-14
- WHAT'S THE DEAL WITH BEHRINGER?, JHS Pedals
- Chandler Industries Tube Driver Overdrive, Pedal of the Day, 2014-12-19
- Butler Audio, Butler Audio
- Seymour Duncan SFX-11 Twin Tube Blue Review, Premier Guitar, 2009-07-08
- Guitar Pedal X, Guitar Pedal X, 2025-12-04
Brad Whitford
Eric Johnson
David Gilmour
