The Keeley Tube Drive - 1950 Sylvania 12AT7WA is a limited, collector-grade dual-gain overdrive pedal that pairs a genuine 1950s Sylvania 12AT7WA high-voltage Class A tube preamp with Keeley's Super Phat Mod circuit, the drive design behind the maker's well-known overdrive pedals. It is a variant of the standard Keeley Tube Drive, which uses a modern 12AX7 tube instead, and it was sold as an RKFX.com exclusive. Delicious Audio reported that the pre-sale on the builder's site sold out within minutes when it opened.12
The two stages
The pedal is built as two independent channels. The Tube Stage, on the left, runs dual triodes in series in Class A and feeds a vintage tweed-amp-style tone stack for warm grit. The Super Phat Mod Stage, on the right, is a dedicated drive circuit that Delicious Audio describes as delivering "punch, body, and sustain while preserving the guitar's natural character."1
Each channel carries three knobs: Level, Gain/Drive and Tone, which allows adjusting the EQ of each channel separately.1 Reviewers highlighted how the switchable routing order and remote switching capabilities turn a boutique collectible into a powerhouse for professional, modern pedalboards, according to Delicious Audio.1
On the standard Tube Drive, Premier Guitar describes the layout the same way: "On one side, you get a genuine high-voltage (168V) vacuum tube overdrive featuring a 12AX7 tube. On the other side, Keeley's Super Phat Mod."4 Gearnews' Julian Schmauch summed up the concept as "a rich tube sound combined with Keeley's Super Phat Mod in a single pedal."5
How the Sylvania version differs
The 1950 Sylvania 12AT7WA edition swaps the modern 12AX7 of the standard Tube Drive for a vintage 1950s Sylvania 12AT7WA, a tube Delicious Audio says audiophiles prize for its lush, deep character and military-grade ruggedness. Per that same account, the Sylvania version leans smoother, richer, and slightly less aggressive, with a tweed-style tone stack in the tube stage.2
"pairing a genuine 1950s Sylvania 12AT7WA high-voltage Class A tube preamp with Keeley's legendary Super Phat Mod circuit"
Editions and availability
The version covered here is the Keeley Tube Drive - 1950 Sylvania 12AT7WA edition, named for the NOS tube fitted in this run.2 Each channel carries three knobs: Level, Gain/Drive and Tone, which allows adjusting the EQ of each channel separately.1 It runs on a standard 9V DC supply rated at min. 500mA, since the pedal converts that input internally to the high voltage the tube needs.1 Reviewers highlight how the switchable routing order and remote switching capabilities turn a boutique collectible into a powerhouse for professional, modern pedalboards.1
| Edition | Tube | Price |
|---|---|---|
| Pre-release Gold and Black | vintage 1950s Sylvania 12AT7WA | $4996 |
| Black and Magenta | 1969 Sylvania JAN 12AX7WA | $5496 |
The 1950 Sylvania 12AT7WA edition was a numbered run of 100 units and sold out within minutes at pre-sale, so it is no longer available new from the builder.1
The Pre-release 12AT7WA edition also shipped with the tube burned-in and fully tested, per Guitar Pedal X's Stefan Karlsson, who listed the "Genuine 1950s 12AT7WA tube, burned-in and fully tested" among its features.3 Gearnews' Jef noted of the RKFX.com exclusive that "each unit cam with an original 1950s 12AT7WA tube fitted. Of course, the tubes were all burned-in and fully tested."7
Power and practical notes
The tube runs at high voltage, and the pedal generates that voltage internally from a standard 9V DC supply with a minimum of 500mA.1 That current draw is well above a typical single overdrive, so it needs its own supply output rather than sharing with low-draw neighbors.
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Questions
Is the Keeley Tube Drive a real tube pedal?
Yes. Each unit carries a genuine vacuum tube onboard: the standard Tube Drive uses a modern 12AX7 running at 168 volts, while the 1950 Sylvania 12AT7WA edition swaps in a vintage 1950s Sylvania 12AT7WA. The tube stage runs its dual triodes in series in Class A at high voltage, with the high voltage generated internally from a standard 9V DC supply.
What is the difference between the Tube Stage and the Super Phat Mod Stage?
The Tube Stage, on the left, runs dual triodes in series in Class A and feeds a vintage tweed-amp-style tone stack for warm grit. The Super Phat Mod Stage, on the right, is a dedicated drive circuit that Delicious Audio describes as delivering punch, body, and sustain while preserving the guitar's natural character. Each channel has its own Level, Gain/Drive and Tone knobs, so the EQ of each can be set separately.
Can the Keeley Tube Drive run on a battery?
The pedal is powered from a standard 9V DC supply with a minimum of 500mA, because the internal circuitry converts that low voltage up to the high voltage the tube needs. A supply rated for at least 500mA is required, which rules out most daisy-chain sharing with low-current pedals.
Where was the Keeley Tube Drive made?
The 1950 Sylvania 12AT7WA edition was built in Oklahoma City as a numbered run of 100 units with a brushed gold gloss finish. Each unit came with an original 1950s 12AT7WA tube fitted, burned-in and fully tested.
How many editions of the Keeley Tube Drive are there?
Guitar Pedal X counts six different editions as of October 2026, each with a different tube onboard. They include the RKFX.com exclusive 1950 Sylvania 12AT7WA version, a Pre-release Gold and Black 12AT7WA edition at $499, and a Black and Magenta edition carrying a 1969 Sylvania JAN 12AX7WA tube at $549.
Sources (7)
- Keeley Tube Drive, Delicious Audio, 2026-08-07
- New Pedal: Keeley Tube Drive, Delicious Audio, 2026-09-01
- Guitar Pedal X, Guitar Pedal X, 2026-08-10
- Take a Thrill Ride with Keeley’s Tube Drive, Premier Guitar, 2026-09-08
- Keeley Tube Drive Twin Triode Dual Overdrive: Dual Tube Overdrive Now Available for Everyone!, gearnews.com, 2026-09-02
- Guitar Pedal X, Guitar Pedal X
- Guitar Journal: Keeley Tube Drive 12AT7WA & More, gearnews.com, 2026-08-11
