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Engineering the Sound: taking the JHS Overdrive Preamp for a test drive

Engineering the Sound took a look at the new Overdrive Preamp from JHS Pedals. They have taken inspiration from a beyond rare pedal from the ’70s. We took a closer look at this miraculous reincarnation.

The JHS Overdrive Preamp is a recreation of a newly discovered and extremely early version of the revered (and at one point in history reviled by some parties, thanks in part to guitar stuntman Yngwie Malmsteen’s thinner-sounding signature version named after his favourite Ferrari model number) DOD 250 Overdrive Preamp.

Early clones and reimaginings of the pedal will be familiar to guitar pedal fanatics, with boutique versions of both the highly sought-after grey early variants (initially believed to be the first versions, with every grey unit sounding somewhat different due to varying parts being used), and of the yellow unit available through numerous new world manufacturers. Throughout the years DOD-branded 250s have also gone in and out of production with varying quality, at least up until 2018 when the company was folded by its current owners.

The legend of the 250

The DOD company took its name from co-founder David Oreste DeFrancesco’s initials (with JHS paying homage on their circuit board, should you crack this box open). DOD began its US-based business being largely accused (in retrospect) of copying the pedal designs of the MXR company — a case in point being the DOD 250’s circuit being incredibly close to that of the MXR Distortion+.

Facsimile circuit or not, the 250 has managed to carve out a niche in guitar pedal history, gracing stages since the mid-’70s with its slight differences in clipping circuit, along with its reputation for a wide overdrive range, from dirty boost with the gain control way down, through to creamy ’70s hard-rock distortion, all lending a hand in slowly building the legend. 

The JHS company is known for its wonderfully fanatic approach to guitar pedal building and collecting. The crew from JHS has exceeded themselves in tracking down a previously unknown large box Overdrive Preamp — older than the grey box variant — and now recognised as the #75 due to its serial number indicating that it is the 75th pedal of any kind ever made by DOD. Whilst on this pedal expedition, JHS sourced yet another early unit; this one with a different diode clipping variant, and from this discovery, the brand new JHS Overdrive Preamp was born.

JHS Overdrive Preamp


Cracking open the box from JHS you’ll find a modern, sturdy surface-mounted circuit, marked with tributes to the original units. Along with the original creator’s name, the original serial number, and reference to the year and city of birth (Salt Lake City, 1973) make an appearance too.

Completely removing the circuit boards from the casing you’ll notice two things — that this is a miniaturised circuit, with two sets of diodes for the sliding switch; one set of which I’m assuming is a pair of surface mount germanium diodes for the #75 pedal version. The other thing that you’ll notice is that it does indeed have the 741 op-amp, however, this too is a miniaturised surface mount version. And it still sounds great!

It turns out over the years of production there wasn’t one fabled op-amp that made the pedal tone; in fact, a reasonable range of different op-amps have popped up in DOD 250 cases, leading one to believe that the combination of other components working in harmony is what actually made this pedal sound so special.


The controls for the unit are classically simple — two knobs, a slider, and an on/off footswitch. Level controls the overall volume, Gain controls the distortion and clipping aspect of the pedal, with the slider providing the exciting variation of clipping sound, with the Down position representing the #75 unit with germanium diodes, and the Up position representing the slightly later clipping variant with silicon diodes.

You’ll find the germanium selection to be notably different with the diodes clipping more of the input signal, with a softer saturation sound to provide slightly less output but maintaining a uniquely smooth, rich tone. Whereas the silicon section is approaching the grey box DOD 250 variant, as different as they all may sound, with its more familiar, classic sound.

The JHS Overdrive Preamp retails for around $260AU and may very well be the final word in the DOD classic Overdrive Preamp discussion. Visit JHS Pedals for all the details.