JHS Overdrive Preamp (DOD 250)

This might turn into half a history lesson coupled with a pedal review.
To keep things brief: We’re looking at the early seventies. Hard clipping has just been invented to find another way to treat guitar signals other than overdrive and fuzz. The year of the distortion. One of the pedals that came out was the MXR Distortion +, another was the Dan Armstrong Blue Clipper. Another one, and that’s the one we’re looking at, was the DOD Overdrive Preamp. In that iteration, it was not yet called the 250, but only a few were made before DOD changed the size of the box and the name.
I do admit that I lacked patience and funds to get my hands on such a revered collectors item. Luckily Josh from JHS pedals stepped in. He himself got his hands on two of those early models and created a faithful reproduction of both of them. One unit has the serial #75 and the other is unknown. You can switch between those two drives with the switch in the middle. You can switch between two of the same pedal? How does that make any sense?
As weird as it sounds, the explanation is rather simple. When David Oreste DiFrancesco and John Johnson founded DOD in ’73, they naturally did not start by setting up a fully fledged factory, but soldered the pedals themselves, probably in a basement. When they needed parts, they went to a landfill and harvested transistor radios and IBM machines, so the early models did not necessarily consist of identical parts. Whatever was available and got the job done was put in there.
There is no “The” Overdrive Preamp, they were all unique. Josh from JHS managed to find two and copied both into a single pedal with a switch to select.
Other than that, it is a very simple circuit. You get an operational amplifier (OPamp) that goes by the name of LM471 that drives a Germanium clipping diode, providing hard clipping. All the early versions of those different brands (Distortion+, Blue Clipper, 250) closely followed the datasheet examples from the chip manufacturer, which explains why they are very similar in design.
Apart from the switch that is an addition from JHS, You get knobs for Level and Gain, that’s it.
The Level knob on the JHS unit also has received a mod, giving the user more dBs to fire towards the amp when maxed – a useful thing that does not really make the pedal sound any different, but gives you more use for it, since you can boost lower gain levels louder.
Both gain and level go from 1 to 10, so you can read your settings. My only gripe with that is that 1 labels the minimal setting and 10 the max. Not only do these not go to eleven, but since 1 is basically 0, the middle (noon) position is actually not 5, but 5.5. It’s purely aesthetic, but still.
The two settings to select from are easily described: One is a lot brighter than the other, but also lacks a bit of low end, while the other is mellower around the top, but has more heft to it. Especially for bass use, the latter feels a lot better than the brighter channel.
With the gain at minimal levels, there is audible distortion in the bright channel while the mellow channel feels clean, although it already adds a little something unobtrusive in the background.

My verdict on the MXR Distortion+ was a negative one. I did not like it much and wrote that this pedal is, measured by modern standards, artificial sounding and redundant.

I wanna say the setting that offers more treble is somewhat less useless than the Distortion+, but still useless — Again, measured by today’s cork sniffer’s standards.
However, flipping that switch to the up position and we’re looking at a completely different animal.
I want to call that the fat/shrill switch, because then, by definition, this pedal has EQ 😉
However, there is a wide range on the gain knob where the Overdrive Preamp adds a little something to the sound without doing much, and that can work wonders in a mix. It gets a little bit more lively and there is audible distortion around the rear edges of the note. The attack is still there and there is sufficient weight behind each note. It is somewhat weird that I compared three (if you count the JHS as two) pedals that follow the same schematic, and two of them are terrible and one of them is fun, but here I sit, happily plonking around on my bass with the Overdrive Preamp engaged.
The audible distortion is spread perfectly even across the entire fretboard, even on my six string. The low B gets the same amount as the B that sits four octaves higher. It feels a bit weird that this pedal, one of the first devices that introduced hard clipping, the prototype of distortion, works great when you want just a gentle sizzle when you pluck hard, but here I still sit, happily plonking around on my bass with the Overdrive Preamp engaged.