The Carl Martin Rock Drive is an overdrive pedal from the Danish maker, positioned in the company's range as the higher-gain option: Carl Martin describes it as having more gain than the Crunch Drive, with a neutral voicing that preserves the guitar's fundamental tone and does not limit dynamics1. The maker calls it a "high-end Tubescreamer" built to emulate classic tube amp tones, from a Fender Twin being pushed to Marshall JCM 800 crunch1. If you are weighing it against other drive circuits, our Overdrive Pedals page and the Boss SD-1 vs Ibanez TS9 Tube Screamer comparison cover the wider family it belongs to.
What it does to your sound
Carl Martin describes the Rock Drive as emulating the sound of quality tube amplifiers being pushed, delivering tones ranging from a powerful Fender Twin clean boost to Marshall JCM 800 crunch1. In practice that places it as a drive pedal that can sit in two roles: a boost that keeps the amp's clean character, or a crunch and gain stage for harder material. The maker's description of the voicing as neutral, preserving the guitar's fundamental tone, is aimed at players who want the drive to sit on top of the instrument's own character rather than reshape it1.
One control the maker highlights by name is the Attack control, which Carl Martin says shapes your pick response and initial transient1. That makes it the knob to reach for when deciding how much of the pluck comes through the gain.
The maker's own description of the pedal, in short:
- A "high-end Tubescreamer" voicing1
- More gain than the Crunch Drive1
- A neutral voicing that preserves the guitar's fundamental tone and does not limit dynamics1
- Tones from a Fender Twin clean boost to Marshall JCM 800 crunch1
- An Attack control that shapes pick response and initial transient1
Power and bypass
The pedal runs on either a 9V battery or an external 9V power supply, and the supply is not included1. Switching is true bypass, which Carl Martin says keeps your signal pure and unaffected when the pedal is disengaged1.
| Item | Detail |
|---|---|
| Power options | 9V battery or external 9V power supply1 |
| Power supply included | No1 |
| Bypass | True bypass1 |
No power supply comes in the box. Plan for a 9V supply of your own, or keep a 9V battery in the pedal.
Where it sits in the Carl Martin range
The Rock Drive is the more-gain sibling of the Crunch Drive. Carl Martin's wider drive range includes pedals such as the PlexiTone, the DC Drive Overdrive, the AC-Tone, the Hot Drive'n Boost, the Panama and the PlexiRanger, each aimed at a different flavor of amp-style drive1.
The DIY side: a published layout
For builders, the Rock Drive has a documented homebrew path. Guitar FX Layouts, an independent stripboard and tagboard layout site, published a vero (stripboard) layout for the pedal in July 20142. The site's contributors noted that original units in this Carl Martin family share a PCB with the CM Heavy Drive, but that there are a number of differences between the circuits2.
The layout's comment thread also worked through the chip options: a contributor reported having three different ICs on hand, a TL074 and an LF347 plus the one specified in the layout, and later confirmed the build2:
"Verified sounds great will post up some sounds tomoz with the different IC"
So the layout has been built and reported working by the site's community2.
Videos
Goldmusicsrl
Derek Buddemeyer
Derek Buddemeyer
Questions
Is the Carl Martin Rock Drive true bypass?
Yes. Carl Martin says the Rock Drive is built with true bypass switching, so the pedal's circuit is removed from the signal path when it is off and your guitar's signal passes through unaffected. That matters on a pedalboard where the pedal stays off for clean passages, since a non-true-bypass circuit can dull the signal it sits in.
Does the Carl Martin Rock Drive run on a battery?
It can. Carl Martin says the pedal can be powered by either a 9V battery or an external 9V power supply. A battery makes it easy to try on a small board or in a rehearsal, while a supply is the usual choice for a permanent setup.
Does the Rock Drive come with a power supply?
No. Carl Martin states that the external 9V power supply is not included, so you will need to provide your own 9V supply or run the pedal on a 9V battery.
How does the Rock Drive differ from the Carl Martin Crunch Drive?
The Rock Drive has more gain than the Crunch Drive, with what Carl Martin describes as a neutral voicing that preserves the guitar's fundamental tone and does not limit dynamics. On the technical side, Guitar FX Layouts notes that original units in this Carl Martin family share a PCB with the CM Heavy Drive, but with a number of circuit differences between them.
Is there a DIY layout for the Carl Martin Rock Drive?
Yes. Guitar FX Layouts published a vero (stripboard) layout for the Rock Drive in July 2014. The site's community also worked through the IC options, with TL074 and LF347 mentioned as alternatives to the chip in the layout, and a community member reported building it and verifying that it works.
Sources (2)
- Rock Drive, Carl Martin, 2026
- Guitar FX Layouts: Carl Martin Rock Drive, Guitar FX Layouts (tagboardeffects.blogspot.com), 2014-07-11
