The Diamond J-Drive Mk3 is an overdrive pedal from Diamond with a built-in, independently switchable clean boost. As the hosts of That Pedal Show put it, "the J Drive is an overdrive with a built-in boost"1. The two halves work separately: the drive section shapes your tone, and the boost section can push the front of your amp or another pedal on its own footswitch.
Pedal of the Day's Mike B described the result as "a warm and even keel overdrive tone" with smoothed upper mids and highs, adding that the pedal "puts out plenty of power and adds great depth to your tone"2.
How it works and how it is controlled
The main drive section has three controls: Drive, Warmth and Volume2. Drive sets the amount of overdrive, Warmth shapes the tonal balance, and Volume sets the output level of the drive section.
The boost section is separate. Pedal of the Day describes it as "an independently switchable clean boost consisting of a Vishay JFET and BJT clean boost"2. On That Pedal Show, the hosts described the same circuit as a "discrete clean boost circuit with JFET input buffering and bipolar Drive"1. In plain terms, the boost adds level and push without adding its own clipping, so you can use it on a clean amp or stacked into the drive section.
| Section | Controls | What it does |
|---|---|---|
| Drive | Drive, Warmth, Volume | Schottky diode overdrive with tonal shaping2 |
| Boost | Footswitchable | Discrete JFET/BJT clean boost, independent of the drive2 |
The clipping itself comes from a circuit Diamond calls "Close Asymmetry," using Schottky diodes2. Asymmetric clipping rounds off one half of the waveform differently from the other, a approach players often associate with a more tube-like overdrive feel than symmetric clipping gives.
Build and components
The J-Drive Mk3 is built around quality-grade parts. On That Pedal Show, the hosts noted "all pro polypropylene caps, one percent metal film resistors" and an OPA2134 op-amp at the heart of the circuit1. Pedal of the Day's reviewer went further on the build:
"the J-Drive Mk3 Overdrive is built with the highest-quality components, and the highest level of professionalism and expertise"2
Mike B, Pedal of the Day2
The Mk3 and earlier J-Drive versions
There was an earlier pedal simply called the J-Drive. On That Pedal Show, the hosts explained the change: "there used to be a J drive, apparently some components started to get less available, so this is the mark three"1. In other words, the Mk3 is a revision built around parts that could still be sourced, rather than a complete redesign for its own sake.
What reviewers said
Both published reviews were positive. Pedal of the Day called the boost section "a great addition" and praised the overall build quality2. On That Pedal Show, the hosts judged the sound:
"in the way that it's fat and thick and full, doesn't completely obliterate the core sound of the guitar"1
Dan and Mick, That Pedal Show1
That balance of thickness and clarity, keeping the core guitar sound intact under gain, was their overall verdict on the pedal1.
Videos
ProGuitarShopDemos
Lance Seymour
Carlo Bova's Guitars
Questions
Is the Diamond J-Drive true bypass?
Yes. The J-Drive Mk3 uses a true bypass signal path for both the clean boost and the drive sections, so with both sections off the pedal is out of the signal chain entirely.
Can the Diamond J-Drive run on a battery?
Yes. The J-Drive Mk3 supports battery operation as well as a standard negative tip 9V DC adapter, so it works either way depending on how your board is set up.
What clipping diodes does the J-Drive Mk3 use?
The drive section uses a circuit Diamond calls Close Asymmetry, built on Schottky diodes for clipping. Asymmetric clipping shapes the two halves of the waveform differently, which players often associate with a more open, tube-like overdrive character.
What is the difference between the J-Drive Mk3 and the original J-Drive?
The Mk3 exists because some components used in the original J-Drive became less available, so the circuit was revised around parts that could still be sourced. On That Pedal Show, the hosts described the Mk3 as the current version of a pedal that used to be simply called the J-Drive.
Sources (2)
- Diamond J-Drive Mk3, Union T&T LAB, Eventide Rose, Fender Tre-Verb: Pick’N’Mix, That Pedal Show (YouTube), 2019-07-29
- Diamond Pedals J-Drive Mk3 Boost/Overdrive, Pedal of the Day, 2015-10-11
